Commodore 128 RGBI/CGA to Analog RGB Part 4: A New Case

I worked up some 3D Printable Cases for the C128 RBGI/CGA to Analog RGB Adapter boards.

I am trying to get away from TinkerCAD, the AMpI4 case (See the post on that here) that I made in TinkerCAD turned out for me. It was a lot of work and it is complex to make modifications to that model when I need/want to.

This time I went back to DesignSpark Mechanical, which is what I started with for the AMpI4 case. I wasn’t ready for a project like that as my first real attempt to make anything in it. This time it was painful as well, but it is a much easier project. I learned a fair bit, but have a long way to go. The case hasn’t turned out perfect, but I’m quite happy with it overall. I make make a couple adjustments to it yet. To start with a made up a mockup of the physical board. That took awhile, then I realized I could export a 3d model of the board from KiCad. When I found that option, I went back and partially started over. I then just had to model the various ports. I did not size them to real world size, I upsized them to be used as the penetrations in the case exterior.

I ended up with making two prototype case prints. The first one showed me the primary mistakes. The SVideo Mini DIN Port opening was too small. The port was accessible with it being properly uncovered, but the outer plastic of the SVideo cable couldn’t get into the opening as it has to go down flush to the port. The RCA ports were correct, they don’t go the whole way down around the outside. The 5V Barrel jack was properly sized for 3 different power cables I tested with it. The DE9 was right. The screw holes placement for the HD15 port were 1mm to high, the whole port was 1mm to high, the cutout and all. This may be due to me using the DE9 measurements as the basis for both openings. I resized the Mini DIN opening, dropped the screw holes for the HD15 port and made the case thicker overall. The first case closed properly, all port alignments were right (short of the HD15 height), the mounting holes for the board and the posts were all correct. I made those adjustments and printed another test of what is now the “all” version of the case. The revised case printed out well, the Mini DIN Port cable now fit properly, the screws for the HD15 were aligned properly and the case was not as flimsy feeling. Once that all checked out, I went back into DesignSpark Mechanical and made up my variant cases from the initial “all” openings case. It was easy to make those variants as it only took a couple minutes. If I was familiar with it I bet it would be more like 2 minutes to do the modifications. I am still very unfamiliar with it, but I like the greater control with the model compared to TinkerCAD.

There are 3 versions of the case, the “all”, the “CGA” and the “C128” variants.

The “all” case has openings for all of the ports.

As you can see the case design is a split top case. There are no overhangs (except the DB/DE screw holes and the underside holes) that require support when printing. There is a slight rounding on the corners. With the settings I am using on my printer it takes about around 1.5hours per half of the case. I normally print faster on my Ender 3 Pro, but the filament I am using didn’t like that. It is some old PLA+ and that particular filament always gets moisture in it. To speed up the process I ended up printing each half on one of my two printers. That is why the filament is different for each, as I didn’t have two spools of the same color. I printing in PLA/PLA+ incase I wanted to paint the case. The color is an acceptable color for the use though. I plan on making up a version of the labels I put on my prototype to put on the tops of the cases. I’ll have to get ink cartridges in the printer before I an make the labels up though. The DE9/HD15 ports have the holes for the standoffs in the lower case shell. The bottom of the case has 4 holes in it for screws to go up through into the standoffs on the top half of the case to keep it shut. I don’t put the Standoffs in tight until I have the bottom screws in to prevent cracking something. With the case design, it does take opening the case to move the jumpers of course. I’d rather not have holes in the top for stuff to fall in, it is also hard swap jumpers in openings like that. It may be possible to rework the PCB to have some sort of DIP Switch. That makes another part to have to source, but it is possible to use that footprint for Jumpers too. DIP Swithes though are generally SPST, not SPDT which is what three of those jumpers need. I do have “mini” SPDT Switches, which I actually intended to install into the C128 type board, but I forgot to. They fit the 3pin Pin Header footprint, and have a narrow somewhat tall slide. These are used on some Commodore 64 (and I am sure other) New and Reproduction cartridges such as my C64 Diag/DeadTest Cartridge. I have also used them on some cartridges, like the C128 Multi Diag Cartridge I made awhile ago. For those mini switches it could be possible to design a case top that let you change them either with small openings, or even make extension caps that let you toggle the switches with the case closed. I don’t expect to be switching the configuration of the adapters often. The SCART to HDMI adapter was unstable in testing the games and was said to introduce lag, I’ll likely just use these with my GBS Control adapter instead. I’d love to be able to use them with my Sony PVM, but it takes a 4V Sync signal, I haven’t even looking at what may be done to adapt that from the ~1V Sync that normally is put out with RGBI/CGA.

The “C128” case is modified to accept my slightly custom RGBI board and has openings for the four Commodore 128 specific ports along the left side. It doesn’t have an opening for the DE9 Male port, as I am using a short “dongle” type cable out the side. It has a smaller opening where the 5V DC barrel jack would be and a second matched opening beside that for my two “dongle” cables grommets to rest in.

I use the short “dongle” cables there for the C128 version as I don’t want to have to make up short stubby cables to plug into ports. I also don’t want to make a custom Commodore AV Cable of some type. It gets more complex trying to find a port and jack for the Commodore AV Cable, then everyone who wants to make one needs to source the same “odd” port and jack. It is bad enough getting the Commodore AV Port “U” DIN connector. Since I am using that short AV dongle there is no good reason to make up a shot stubby DE9 Male to Female cable either. In my case that is part of an old DE9 Serial Modem cable. The grommets fit the cables snuggly and are from a case of grommets I picked up at Harbor Freight. I sized the holes to accept those grommets.

The third type of case is the “CGA” Case. It doesn’t have any of the Commodore 128 ports on the side, but has all the other normal openings in it. The case should be easy to modify with various 3d modeling packages, even with Tinkercad or such if you want different openings.

The case isn’t perfect but I’m happy with it. The holes in the bottom were meant to take recessed M3 screws. The recesses aren’t deep, or wide enough. I have already printed 4 cases today for just 2 adapters, so I don’t plan to rework the recesses. I also don’t have any tapered M3 screws of an appropriate length. It seems to close well with M3 screws, I made the holes in the top standoffs to be hollowed out quite deeply, but something like a 10mm or probably 8mm screw is sufficient. My cases are printed out of PLA on two different printers and the holes worked well on both, the holes are a good fit for the M3 screws on both, but each printer is a bit different. I thought of putting Brass Standoffs in, which takes a larger hole, but there is alot of variation on what size and depth they need to be. It is hard to make a “universal” case when using brass standoffs. I have some super cheap thin ones, them my good ones are massive.. When sitting the case together there is a slight pulling at the corners, but on putting the screws in the minor gaps close up tightly. With my cases the fact it is made of two different materials does make it stand out a bit, but I kind of like the look. It should print fine in PETG. I used PLA as I have more color options, and if I decide I want to color match it with paint, PLA is the better option. I like doing prints in Transparent PETG, but this is for use with an 80s Era Computer not an iMac. I have a couple opaque PETG filaments, but not one in a color that I felt was appropriate.

Above are pictures of the closed up cases from various angles. I also showed some bottom views where the screws are present. It is quite bland looking and you can’t tell what it is for by just looking at it. I want to make labels similar to the prototype, but I’ll need ink for the printer before making them.

After assembly I did some testing with the Commodore 128 with my GBS Control (see post on that for details) taking the 80 Column output the rest of the way to standard VGA.

I did test the Monochrome Composite 80 Column Output after doing my bodge on the V1.2 board the Monochrome Composite 80 Column worked properly after. The Monochrome 80 Column is fixed on the released V1.3 Board design. I really don’t know why anyone would use it, it can very easily be used just connecting directly to the pin on the RGBi Video Port. I only added it because I could.

The KiCad files, Gerbers, Schematics, Bill of Materials and 3d Models are all released at Github:

I went back and finally looked at H2Obsession’s “Ultimate” adapter project. He included a “Dark Gray” fix as well. I wasn’t aware there was an issue with Dark Gray. I’ll have to look at it and see why that was done. It should be simple enough to add. I’m also thinking about the PVM taking 5V CSync for RGB. I’m wondering if I could come up with an option for that.

Here are a few pictures of the Commodore 128 setup. It is a bit crowded with projects, most of them have posts here on the blog. The Commodore 64 replacement Power Supply, a Commodore 64 to Commodore 128 Power Supply Adapter cable (I don’t have post about it, It takes the C64 power jack on once side and the Commodore 128 plug is from “Hey Birt!”‘s store. My C64 power supplies were built for higher current than the factory model making them able to handle the C128’s requirement fine). I do have the serviced Commodore 128 Power Supply, but it is easier to just swap in the adapter cable, than having both out on the desk. The Commodore 128 is connected to the Samsung TV I repaired. I of course have the RGBI Adapter tucked in under the monitor. I do have the Monochrome Composite 80 column connected up to the TV, as I was testing it. I also have the 40 Column SVideo connected to the TV. The RGBI Adapter is connected across to the GBS Control (silver box on the right under the pi1541 which is another project). Then the Commodore 128 which I serviced, but I guess I have no post on servicing it. I’m still debating painting it, I won’t be retrobrighting it.

Finally the gamepad project, which I don’t have a post about. It is far from flawless, the Dpad isn’t great. It has 2 buttons, the normal fire button on the left and “button 2” is either “Up” or wired to one of the Pot inputs. It also has an adjustable speed 555 based Rapid Fire option for the primary Fire button. I want to revisit that project, maybe then I’ll make a post about it.

Commodore 128 80 Column RGBI/CGA to RGB Analog Adapter Part 3

The boards arrived today. They look good, short of some labels having been reset shortly before making the order that I want to fix. The biggest being the Commodore AV Port header is unlabeled.

I checked placement of all the parts, and I found one issue. ( Thought I found an issue, but I figured out later that the unmodified RCA Jack does “just fit”, it is just quite tight.)

The RCA Jacks fit their footprint perfectly minus a bit of an issue with the back pin. These jacks are apparently intended to have the plastic pins on the front just sitting on the board. I put holes on the footprint to recess them in the board in hopes of a little more durability. The back pin won’t fit through the board.

With a quick touch up using the Dremel I made the Yellow jack fit nicely. I filed that little upper lip off. My intention was the alter the rca jack footprint to have a longer slotted hole in the next revision. Looking at it closer though and trying it, I can just get the pin to go into that footprint. It is snug, so I am planning on leaving the footprint as is. The jack doesn’t “have” to be filed down, but it is a bit fiddly to get in if you don’t.

I am making up two of the boards. The first one to replace my original adapter for the Commodore 128. That one will reuse the short Commodore AV Port DIN Cable and the short DB9 Cable from the original. The other board I am building up as a CGA adapter board, I am leaving off the Commodore AV Port parts (mostly) and adding the Barrel Jack for the 5V DC input. I don’t currently have any computers that use CGA, but I figured I have five boards and plenty of parts to put one together


The original adapter and the two new ones I am looking to assemble.

I salvaged the cables, ICs and one of the sockets from the original unit as I am scrapping it. I wouldn’t have messed with the IC Socket except I was practicing with my desoldering gun. It turns out I only ordered one VGA port, so I had to salvage one from an old monitor switcher board I have. I managed to get it off, and it is the same footprint as the new one. It wasn’t too easy, but went fine.

The two boards after soldering.

They turned out looking pretty good overall. The right board is the CGA board without the Commodore AV functions. It will take IBM CGA and a 5Volt DC Power adapter to make it into an Analog RGB signal with the CGA Brown Fix applied. That can go into a GBS Board, GBS Control modded board or something like a SCART to HDMI board. The primary limitation with the SCART to HDMI board (other than a lot of latency) is there would be no Audio on the SCART as CGA doesn’t have audio on the cable (for the Commodore 128 the Audio comes from the Commodore AV DIN Port). That and you need a Analog RGB to SCART cable, which my cable is a bit custom, see my cable pint out in the “original” project post from 2019.

The board is a perfect fit into the project box that I used for the original adapter. The openings are all different though, and you can just drop it in once the ports are soldered on. I guess you could “slot” in all the openings, but that leaves gaps from the top, which I don’t like. I plan to design a 3d printable case for the board. That is a part of the project that will have to wait until next weekend and likely longer though. I want to make it so it had all the required openings and is a simple split case that will fully enclose the board.

I do have to check that the boards are wired properly, mostly the Commodore 128 version with the cables. Then I will test the boards and see how it works. I will make the required corrections and changes on the pcb design and upload them to Github.

Above are some pictures of the testing. The Monochrome 80 Column pass through doesn’t work. I wasn’t thinking and passed it through the 74LS244 buffer, which it doesn’t work that way. The v1.3 board design no longer passes the Monochrome 80 Column video through the 74LS244. That is corrected on the v1.3 design I released on Github.

The rest of it works. RGBI works, 40 Column Commodore Composite pass through works. The 40 Column Commodore S-Video pass through and Audio via the RCA Port work properly. My Commodore 128 is being odd, I am not sure if it has something wrong with it, so it has limited my testing options. I did work on the C128 awhile ago, and it all appeared to be working except the cartridge port was being problematic. I haven’t been able to get it to work fully with the pi1541, although the 80column programs I tested are working through the pi1541. It may be because the pi1541 I am using is the 3A+, and the sdcard is setup for my 3B+ instead. I think there is a setting change required for timings.

The first image is through the GBS Control, with scan lines enabled. I have another post where I build GBS Control if you want to see that. The next being the adapter board connected up to the GBS Control. The second row starts with the SCART Converter to HDMI on the same color test. It is brighter due to no scan lines. Then the SCART Adapter connected up. The last picture was me testing an 80 column game using the GBS Control. I did find that the SCART Converter was not being stable when in a game though, it was flickering and blinking in and out. The GBS Control was stable on the same games. I am wondering if it is something with the sync signal. The one IC is a HC chip, which should be either an LS or HTC, that may be doing something to the signal that the SCART Adapter doesn’t like. I have another IC on the way. I’ll be testing the SCART to HDMI again when that comes in. I also did the bodge for the 80 Column Monochrome output and I will be testing that when I put the boards into their new 3d printed cases.

Part 1, prototype build:

Part 2, board design and parts list:

I am going to see about doing a bodge on the 80 Column Monochrome output and test that. If that works out, I think it is ready to post files for download. I am working on a design for a 3d printed case check the Part 4 post for the case and design files.

Part 4, 3d Printed Cases and links for the Released Files:

Commodore 128 80 Column RGBI/CGA to RGB Analog Adapter Part 2

This is a follow up to an older project I did. The RGBI (RGB Digital) to RGBA (RGB Analog) for the Commodore 128 80 Column Video. Commodore’s RGBI is essentially the same as CGA so the adapter works on either. I made my prototype adapter back in 2019. I wanted a project to work on and wanted to work with KiCad to see how that went.

The Original Project:

I had started making a PCB Design in Eagle back in 2019, but I never finished it. I didn’t want to keep using Eagle so I stopped working on it.

This project is the RGBI to RGBA project packaged into a custom PCB Design and with a few additions. Such as a dedicated 5V DC Power Jack for when using it with an IBM Based pc for CGA.

It still has all the Commodore functions and more passthrough functions now for the Commodore 128. The Commodore specific parts could be skipped though.

Below are some pictures of the PCB Design work in progress.

3/4/23 the unfinished v1.3. I still need to change the RCA Jack Footprints. Then I think v1.3 will be ready to post to download.

The board is sized to fit into the same case I used for the prototype. The problem with that is you can not get it into the case with the DB ports soldered on. I still laid it out for that size and the mounting holes to match that case. I have a couple of them yet. I think it would probably be better to design a 3d printed case. I can make it split at the place I need to get it in and out easily that way.

The board layout is basically a DB9 port on the left side for the RGBI/CGA input. Along the top the first port is for a single RCA Port for 80 Column Monochrome output from the Commodore 128’s RGBI Port. It is there, so I figured it is easy to include. You don’t need an “adapter” to use the Monochrome output, it is just Pin7 on the RGBI DB9 port on the back of the C128, I am passing it through the 74LS244 buffer though. The next footprint is a SVideo Port for from the Commodore 40 Column from the AV Port, including a 300 Ohm resistor on the Chroma line. The next port along the top is for another RCA Port and it is the Commodore 40 Column Composite Video from the AV Port. The last port along the top is a third RCA Port which is the Audio Output from the Commodore AV Port. There along the right side is the 15 Pin RGB Analog Output. The bottom left has the 5V DC Barrel Jack footprint (Center Positive). The Header pins are the C64 AV Port, it is oversized as I want to make it “keyed” with a missing pin and a plugged hole in the connector. The CSync/HSync is to set the Sync output for the normal HSync pin on the VGA port to either be Combined Sync (CSync) or to just pass through the HSync normally. The Audio header is a jumper to either output the Audio to the RCA Port above it when in the Left side or to output it on the VGA port on Pin10 for when I use it with the SCART to HDMI Converter box. InvertSync is another jumper to Invert the CSync/HSync line if needed. Finally the SCART Blanking is a jumper to enable sending VCC/5V to Pin9 on the VGA Port again this is for when I use the adapter with the SCART to HDMI Converter box, this enables the SCART RGB Detection on SCART Pin 16.

I think it is a reasonably sized board. If it was to be used for CGA with an IBM Computer then you can install the Power Jack, and omit the 3 RCA Ports, the Mini Din Svideo Port and the 10 Pin Header for the Commodore AV Port. If it is going to be used for a Commodore 128 RGBI, just build the whole thing minus the Power Jack. I think the only thing with the power Jack is that plugging it in while having the Commodore AV Port connected could end up very bad. I might think about that a bit more if the 3pin Barrel jack could be setup to bypass the AV Port power or something like that.

I did go with through hole for the ICs, headers and ports. I was thinking of going with dual footprints for the Resistors and Capacitors to allow either through hole or surface mount parts. The Surface Mount capacitors and Resistors are 0603 Imperial size parts. I have all the ICs already in DIP/DIL, and I want them in sockets for easy replacement if required.

I had to make the footprints for the RCA Jacks, and the SVideo Jack. The RCA Jacks should have square holes on the front corners. I couldn’t see how to make such cutouts. I figure that I may just have to shave the plastic a bit on the RCA Jacks.

The board as well as the original prototype build can do a combination of outputs depending on your needs.

The board in the fully configured mode outputs RGBS, Red, Green, Blue and Sync (CSync or Combined Sync) with custom Audio and SCART Blanking voltage on the HD15 port. This is what you use for a SCART Input. With the Audio to the RCA Port and the SCART Blanking disabled (may or may not be an issue if it is enabled) the GBS Control also takes RGBS input. The GBS Control might get confused due to VSync being included too on the HD15 all the time. With the SCART Cable the VSync pin is just not wired to anything.

If it is set to HSync with the jumper then it outputs RGBHV: Red, Green, Blue, HSync, and VSync. VSync is always on the HD15 port. The GBS Control takes RGBHV, and that is the setup I use with it.

It will also do RGBS with an Inverted Sync with the other jumper. I think did that variation because of something to do with the GBS boards at the time. I don’t remember what it was about though for sure.

The other two jumpers are specific for doing the RGBS with SCART, that puts Red, Green, Blue, Sync, Audio and 5V on the 15 Pin output. It is how I used this adapter until I build a GBS Control to go with it. The GBS boards weren’t as good for this use until the GBS Control project came out.

When using the adapter in RGBHV mode the 74LS86 is not required. The 74LS86 is just used to make the CSync by combining the HSync and VSync. It is also used to do the Inverted CSync if that is enabled (which it would also Invert the HSync technically if it was enabled while the other jumper was in the HSync position). If you look at the schematic you will see it is just bypassed. The 74LS244 is a buffer to protect the Computer video output. The 74LS138 handles the CGA Brown Fix.

I have received the parts I had on order and checked all the footprints. There was an issue with the DB9 port footprint that I had to fix. I also had a few adjustments to make to the Mini Din 4 for the SVideo port. I made changes for footprint corrections and some adjustments to labeling then put in an order for the v1.2 PCBs. I am going to build one to replace the one I made in 2019 for my Commodore 128 RGBI, as I want SVideo. I plan to scrap the prototype, reusing the short DB9 cable and the short Commodore AV Din cable I made for it. I also plan to build up a second one for IBM CGA without the Commodore AV Port related components. If the board tests out, I will post the KiCad project files and Gerber files on Github. Once I have the boards built up, I intend to design a case that can be 3d printed.

Update: 3/4/23 v1.3 I am correcting the schematic, the original one had the 80 Column Monochrome Video from the Commodore 128 RGBI port going through the 74LS244, and it shouldn’t be. I am also adding R11 as an option for a “Resistive Ground (RG)” on the Shell/Shield of the 15pin output port, it probably should have a 100 Ohm resistor between ground to help prevent potential Ground Loop issues. To prevent ground loops with the cable shield is generally recommended to only be “grounded” on one end, so you can put in the optional R11 or omit it. All of the other connectors have their shield to GND/Ground.

Parts List:

0603 – Resistors
1) 150
1) 300
2) 470
1) 560
3) 680
1) 1k
1) 2k

0603 – Capacitor
3) .1uF 100nF

RCA Jacks
1) Black RCA Jack
1) Red RCA Jack
1) Yellow

Svideo Jack
1) 4Pin Mini Din

1) DB9 Male
1) DB HD15

1) 74LS244
1) 74LS138
1) 74LS86

Optionally a surface mount barrel power jack. Various pin headers and a couple jumpers.

See the next part of this project. Building, testing and fixes below:

Finished project:

Remaking Commodore 64 Cartridges

I ran into an issue with some old Commodore 64 Cartridge Roms that I purchased. I found 4 Rom chips with a single PCB for sale and purchased it. The PCB had an old socket on it to swap the chips around, all four chips worked on the board. Still I wanted to get them all usable again as full cartridges. I purchased some 3d printed cartridge shells at some point after that. There is also the issue that with the cartridge shells you can not us an ic socket, it makes the chip sit too high to close the shell.

I decided to look around for some PCBs, but I couldn’t find any with the proper footprint for the origional Roms that have the 2364 pinout and not the 2764 which is what the common Eproms are. So you can’t use a socket, and you certainly can’t use a double socket adapter to make the 2364 type chips to work on the modern pcbs.

I had not yet worked on any PCB designs. It is a lot of work to go from scratch for something like this if you aren’t familiar with it. The main issues are recreating the physical board in the right dimensions, as well as the proper size and placement of the hole in the board and the edge connector itself. With those in place it would not be too bad.

The original board after removing the socket and putting one of the ROMs on it.

Still I had not worked with Eagle much. I did find a project on Github with Eagle design files. I tried to start working on it, but just wasn’t getting it at the time. Part of my issue is I have four Roms and one board already. I only needed three boards. I didn’t want to order in 5-10 PCBs to only ever end up using three of them. That would have been quite a waste.

It has been a good while since I put those chips in some ESD Foam for storage. I recently purchased some premade PCBs for other projects, which you can find the GAL PLA replacement post here which is one of the boards. Another of the boards I purchased was a 2364 to 2764 adapter board. The GAL PLA was so easy to put together as well as the 2364 adapter that I really wanted to get back to this project.

I looked around and had seen some of bwak’s stuff. I found his Versa64Cart over at Github.

It looked like a great candidate as it was available with the Eagle files. I haven’t used Kicad and the other project I found only had files for it. I wasn’t up to learning another program just for this project. Bwak’s design is also the most complete and has all required documentation.

The only thing I really had to do with bwak’s design was add the 2364 footprint beside the 27xx footprint and wire it up properly. I was careful and used the design for the 23 to 27 rom adapter as part of my reference.

I also did some other reading of cartridge schematics and reverse engineering the original PCB I had received with the ROMs. In the end I put on the 2364 footprint, I tried to use an existing Eagle Library that had it in it, but there was some issue with the footprint in it. That lead me to making a new footprint for it in the library using the standard DIL/DIP footprint. It is the oval pads rather than the minimal round ones that bwak used for his footprints though.

Here you see the 2364DIL24 added to bwak’s schematics

I also added a jumper between EXROM and IO2 to the board. The only reason I added that was because the Original PCB I have has them wired together. I have seen no other point at which those are referenced as being wired together. These specific ROMs are set for “GAME” and “ROMH”. EXROM is not used on these cartridges. I have found no reference of IO2 or IO1 used on any standard cartridges, maybe they are used for bank switching cartridges? If that jumper was connected AND “EXROM” was tired to ground, that would Ground IO2, which is probably not good. Beyond those changes the board is the same as bwak’s 1.5 design. This will let me use my remaining boards with some 27xx Eproms or EEproms.

In the end I ordered 5 boards from JLC PCB. You can see the IC2 and JP1 footprints below on the Gerber viewer.

The PCBs arrived 7 days from ordering them. That was manufactured, packed and shipped from China to the Eastern United States. They do say two weeks estimate, it was very impressive to get them so quickly. I got them for a bit under $20 for the five boards shipped to me.

Front and back of the board after it arrived.

If you look at my board compared to bwaks’s 1.5 the ground plane is different, I think I widened the gap between traces, as well as the additional footprint for the other socket is probably blocking some areas. The old boards had no ground plane it is not a big deal. I usually like to fill it out as much as possible though, for this it is not important.

Here is the first one I assembled beside the old board.

When they arrived I tested them against the original PCB. Everything checked out, the boards all looked correct with no defects. I did have to round over the card edge connector though, I expected that. I didn’t want the sharp edge there going into the C64. It was easy take the edge down with some sandpaper on a sanding block with a few passes across it.

The next thing I needed to do was solder on one of the ROMs, the capacitor and do the solder bridges for the GAME and ROMH pads. Initially it did not work, but that was because I forgot to do the GAME solder bridge before testing it. I did that and it worked perfectly. For the next three ROMs I soldered one onto the original board and prepared two more of the new boards for the last two. They all tested out and worked properly. The next thing was to put them into the 3d printed cartridge shells. That was easy enough, I will say compared to the old PCB, which fit perfectly into the printed shells that the new boards are slightly different. They are maybe .5mm to wide to fit, the hole for the screw must also be about .5mm to high or maybe even 1mm . This meant I had to slightly shave the 3d printed shell to fit the pcb into it, not a big deal. The hole placement means they are sticking slightly out of the bottom of the cartridge, but part of that is these cartridge’s seem to have the screw about 1mm to low or so making that fractional difference between the old board and the new ones a bit more pronounced. The old PCB even is about sticking out of these shells.

Showing the old PCB and the new one.
Here are all fully soldered up and ready to close up.

I am working on modifying a 3d printed shell design for my remaining boards, as those are the only ones I had. I had purchased them specifically for use with these four Original ROMs. I do have an Ender 3 Pro and can print them now, which back when I purchased those. There are a number of designs on Thingiverse, and if the Customizable design worked, I could generate exactly what I wanted with it. I haven’t had any luck with getting the Customizer working on that.. So I picked up a few other designs and started tweaking them with Tinkercad. The primary design I started with is a Stumpy type, it perfectly fits that old factory PCB, but that is the tallest it will accept. That is fine with me. It looks cute and takes up a bit less space, is quicker to print and takes less material. The problem with it is that the screw hole is not placed properly, and the diameter of the standoff is incorrect, is also lacks support to keep the cartridge from rocking back and forth along it. I have been working to get the screw hole placement correct, as well as fit the other issues with the standoff there. I took the screw part of another cartridge design and replaced it, then printed it. I had placement corrected, and the length of the pins was great, the problem being the shaft was too large.. why.. So back to working on it. I did get it downsized properly now. It will use a M3 screw, so I reworked the face to accept a threaded brass insert. I have it all ready to do another test print, and I hope this third version works out.

Here they are closed up with my second test print of the Stumpy shell

The short shell is going to be for the remaining boards and probably a few other modern cartridges. The original cartridge board fits it perfectly and is the longest that will fit in it. The Versa64 board a bit shorter so they fit well. I was thinking of making an even shorter version, but then it may get to be difficult to remove. I am thinking of maybe making a post about the shell if I do something interesting with it. It does not have the removable nameplate, which it really can’t as the screw mount is on the back of it.

The last thing I did with them was print up some labels with my Brother PTouch Labeler. I thought of doing some printed labels on my inkjet printer, but they can fade or smear. I have made reproduction labels for cartridges that way as well as labels for other projects. I would generally put clear packing tape or a clear laminating tape over them to protect them. With the removable nameplates, I have been thinking of 3d printing some, I have to properly reproduce the inserts first. I don’t have the files for these as I did not print them myself. I would then do multicolor printed labels like I have done for my Bartop Arcade joystick rings.

You can see they aren’t any high value Cartridges. Still, they are complete and easy to use again. My projects are often about learning to do something new or get better at some things I have done in the past. I like the bonus of getting something useful in the end. I may not use these that often, but I am glad that it will be easy to do so now. You can see how close the PCB is to the cartridge’s shell. Radar Rat Race is actually the old pcb, and even it is sticking out a bit.

This is just another quick easy project that I did. It is so much easier to put together and finish it with a proper PCB. I had toyed with the idea of designing and etching the boards myself. The ones I make were a very delicate and complicated project. I really don’t want to do any more of them anytime soon. Being a double sided board makes that much more particular in alignment. Cutting the boards correctly, drilling, etching… It is a lot of work, the lack of solder mask and through holes make it far more complex to assemble. I also design the boards with more space between traces, as well as going with as few through holes as possible when etching my own.

I certainly expect to look into getting PCBs manufactured for future projects where required. The tough thing is for one off projects they are rather wasteful. I don’t want to buy 5 of them and only ever use one. Prototypes often end up with some mistakes, so I might order 5 and not be able to use any, or use one of them and have to rework on the board making it a bit of a mess.

Another Pi1541

I now have three working Commodore computers. Two 64s and a 128. I felt I wanted to have a second Pi1541. I didn’t have a non repairable 1541 laying around this time though. I do now have an Ender 3 Pro 3d Printer though and a little experience in working with it and 3d models. This gave me the interest in making a much smaller Pi1541 that looks a bit like the 1541ii. I figured that styling fit better with my Commodore 128 as well.

I didn’t need another Tapuino. There was talk of Steven adding .tap support to the Pi1541 back when I built my Pi1541 & Tapuino. That seems to not be making any real progress though so far, but it may yet happen. It may have and I missed it. Steven White and any other contributors have done a great job with the Pi1541 though. It is a great thing to have around.

My first Pi1541 case had so much room that I wanted to make more use of it, it has a 7″ Composite LCD than can be toggled between the Pi and an external input, an internal mono audio amp that can be toggled from the Pi (with a simple mixer to mix the stereo from the Pi) to an external input, it also has access to the USB, Network and HDMI from the Pi, as well as a bare Tapuino. It has controls on the front panel for the Pi1541 and Tapuino functions, as well as the SD Cards for both the Tapuino and Pi. I can take it and one of my Commodores and use it as a portable 7″ monitor with Audio for the Commodore 64 or 128. I can swap the SD Card and use the 7″ LCD for the Pi and run any other Pi OS, or connect the HDMI to a TV and use another Pi OS be it RetroPi or Raspbian etc…

This one was built to be more like the common Pi1541s out there. To be rather minimal in size, but do the job.

There has been a problem for me and the Pi1541 in that the Pi3B+ has gotten expensive with the release of the Pi4. I guess it is supply and demand. The Pi4 has a different architecture so it can not work as a Pi1541. I am betting there are quite a number of other projects that probably are in the same situation. Steven did come out with a Pi Zero version for the Pi1541, and as I was going for “Small”, and these are cheap I purchased one for my new Pi1541. Then I found out you have to overclock it, and it doesn’t support all of the features that the Pi3 does due to the more limited cpu and ram it has available to it.. So that idea was scrapped. There are other Pi3s though that are still more reasonably priced and support all of the same features with the Pi1541 as the Pi 3B+. So that brought me to getting a Pi 3 A+. They are slightly less powerful than the 3 B+ model, but they can still be purchased in some places for $25.00. Granted I can currently get a 3 B+ for $35 at which is where I purchased my Pi 3 A+ at for $25. Maybe there is less of a shortage right now. I still have a hard time spending $35 even when you can buy the more powerful Pi4 2gb for the same price (and the 1gb model for less)..

The next thing was to find a case design that I liked. I don’t like having bare boards laying around. I also don’t like simple block cases a lot of the time. I came across a case design on Thingiverse that I mostly liked.

Like I said I “mostly” like the case. Mike from thegeekpub used this case for the Pi1541 he posted a video on. It is styled after the 1541ii. It is listed as a “work in progress”, and kind of is. I made quite a number of mostly small changes to the case for my needs. Some were functional changes, some were cosmetic. The case is a 4 part case in the current design, the pictures at Thingiverse don’t all reflect that.

My prototype print. The only change being the rectangle LEDs at this point.

So let us go with the cosmetic first. I wanted Rectangle LEDs like the real 1541ii. My skills with 3d modeling are limited. That was one of the points of this project though, it was to help learn a bit more in that area. I use Design Spark Mechanical for 3d modeling. I have used Tinkercad for past simple models or modifications, but that certainly wouldn’t work with this project. My first attempt on the LED openings was to take the round holes and close them and put the rectangle openings into them. I managed that and made a prototype print of that for fit etc. I learned a bit with that and what I needed to make more adjustments with. I had to make the openings a little larger to accept the LEDs, also even then a bit of filing was done to the final print. The LCD wouldn’t quite line up with the LCD opening. The later “final” print I managed to move the LEDs stacked to the left edge like I wanted to start with. They were a bit easier to fit, but still took a little filing of the openings, it is hard to print a sharp enough corner.

Here you can see the LCD alignment issues a bit.

I enlarged and relocated the LCD opening a bit the alignment wasn’t quite right for my particular LCD. It may not be quite the same for all of these types of LCDs.. I also angled the top edge, as the depth that the LCD sets back made it so that I would have made it even taller making it odd to look strait on at. The other change I made to the face was cut a slot into it where the “disk” would have went. I like how that looks better.

I did not use a Pi Hat PCB, so in the back I needed to close the opening and make a circular opening for the DIN socket I used. I did that by adding on to the narrow “center” part of the case. Closing it was fairly easy, making the proper opening then for the Panel Mount DIN socket and screws was done as well. To provide some support when inserting the socket I put a lip on the inside of the top cover. This does not protect the socket when pulling it out though. If I had put the socket in the Top of the case, it may have been stronger but would have been more difficult to work with.

First prototype on the back opening. I didn’t make the “tab” tall enough. I don’t yet have the inner “lip” to help support the socket.

The last part was the bottom of the case. With that I made a change to one of the standoffs, with the Pi3A+ it had a component on the bottom hitting and pushing it off the standoff. I didn’t want to damage my Pi.. I think a Pi3B+ doesn’t have something quite as close to that spot. I closed some of the opening in the bottom where the SD Card opening is, I didn’t want it any more exposed that required, it was only a minor change. The more important change was on the side where the Power, Audio and HDMI ports are. For one I closed the areas up a bit, raising the bottom up, the top down, putting in a bit of a panel at the one place that didn’t have one. I also had to widen them, I couldn’t get my cables in at the ports, and it wasn’t because the openings were shorter now. Maybe some cables are a bit more slim, but mine are not. My final intention was to take some thin plastic something like a transparency and cut the USB, HDMI and audio/video jack out to use as a backer to close the rest of the opening and not block access to the ports to make it a bit cleaner. I haven’t gotten around to that. I did do something like that on my large Pi1541 for the one port in the back.

Here you can see the Pi3A+ installed in the prototype case. There is room for a Pi3B+ but the usb and network ports would not be accessible. Those little blocks on the right side that do not exist in the upper center part are areas I added some material on the bottom part to make the openings look a bit neater to me.

For the inside I did go with hand wiring everything using some protoboard. The front control panel being fairly easy to do, short of alignment of the LCD. The buttons as designed work great, it is an great design.

Here you see the back of the control board in the front. The LCD and 5 buttons are on the front side.

For the Pi1541, well I make what I call an Option B+SRQ design for the Pi1541.. This is Steven’s Option B plus another Level converter and wiring up the SRQ lines. I will have to update this post with the schematic. You can find the schematic though that I used on my Pi1541 + Bare Tapduino project. Just note that one includes a Tapduino in addition to the Pi1541 section. I can’t find an Option B+ wring diagram, it has been unfortunately rather vague on how the later additions to the Pi1541 are wired up. For my reference I did modify the Option B wiring diagram to be a Option B+ but as I didn’t make the original diagram I won’t post the modified one. The SRQ is required for the high speed emulation of the later Commodore drives with the 128 I think.

I don’t believe my schematic is the best to follow. I think a Wiring Diagram is generally easier for someone to follow. The schematic below is from my Pi1541 + Tapuino The SV2 header goes to the Pi to various pins. I am sorry it is not the best to follow.

To make the main Pi1541 board section, I used another piece of protoboard with my required IC and two level shifters. Also the filter capacitor and resistors etc. Everything connects back to this board, then this board goes off to the Pi3A+.

Here is the start of the main interface board. It had a lot to add yet.

Below is the completed electronics. The White 3d printed parts were the final parts I made. The front being the LED placement, LCD Opening and Slot changes. The middle ring with the back tab at the proper length. The interface board is mounted with the two screws that hold the middle ring in place as well.

Completed internals

Below are pictures of the completed Pi1541.

Final front. There are some 3d printing minor defects.
Here you can see the LCD Alignment is much better that the prototype.
The port in the back with the tab height corrected, it also has the supporting inner lip on the top cover. Still with the yellow bottom. Then the odd bonus of seeing the Pi LED in the back.
The side view with the yellow bottom. The USB and HDMI are just a bit narrow. Yes the PLA case is a bit translucent.
Might as well have the top view too. Yes that is my Pi1541 schematic in the background.

I figured I would do some size comparisons to my other 1541 drives.

Here is my 1541ii drive with it. I used the same Green and Yellow LEDs. I have seen other 1541ii with different colored LEDs though?
Here is is with my 1541, and my Pi1541 + Tapuino. It is far more compact.

Does it work? Yep.

I have printed a white bottom for the drive and installed it. The difference being the color and slightly wider openings for the USB and HDMI ports. Over all this Pi1541ii design should be easy for someone to build for the most part. With a Pi1541 Hat that fits the alignment of the original case, just print the original center part without the tab added. It can accept a Pi3B+ as well as the A+ just fine. Then the only bit to custom build is the front panel board, sure a pcb could be designed for that to even make that easy.

If anyone wants the modified 3d models I should be able to get them to you. If there is interest, I would probably look into the option to post them as a modified design on Thingiverse. I have never looked into that though and do not know what is involved. I don’t think the support rim on the top cover should get in the way of the Din plugs in the back if they line up properly. The main modifications were the tigher fit on the bottom, as well as the changes on the front of the case.

You can check out the Pi1541 site for the basics and the wiring diagram for the Option B design. It is just adding the SRQ lines with another level shifter. All of the required pins are labeled on the GPIO header in that diagram. There are what I call the Option B Plus Pi Hats out there for sale. That is why I don’t understand why there has been no Option B Plus wiring diagram posted.. You can also now use a Rotary Encoder to replace the UP/Down and Select buttons. I like the idea of the Rotary Encoder, but it didn’t fit the case design. For my Pi1541 + Tapuino I did use a two way toggle switch for the Up/Down controls to eliminate a button. I might have used a Rotary Encoder on it had that been an option at the time and then I would have only needed 2 buttons not three.

Commodore 64 GAL PLA Replacement

Back in March, Adrian at Adrian’s Digital Basement posted a video (and a later follow up) on a cheap PLA replacement made with some still accessible GAL chips. When I saw it I picked up 5 of the required GAL chips. You need two chips to make a PLA replacement from them. The actual chips are GAL20V8B chips, preferably the -25LP but with an alternate programing of the one chip you can use the faster -15LP chips instead. The chips can be programmed by downloading the .jed files from the Daniel’s project website:

While the GAL20V8B chips are no longer manufactured, they are in Daniel’s words still rather easy to get and cheap. The chips are able to be programmed in the popular TL866 programmers. I have the newer TL866ii Plus that I purchased for programming EPROMs. There are the older TL866 programmers and those work too, which is why he choose that model of chip rather than a similar still in production chip. This indicates that if someone wanted to they could likely recreate this project with that still in production chip at some point, but unless there is a shortage on these chips I doubt it will happen.

I happen to look around for parts and projects, so I had the chips laying around, but I have never pulled the trigger and ordered any manufactured PCBs from any of the providers out there. If you read my other posts you will see I have designed a couple of my own and etched them at home. That is a lot of work. These premade designs are not meant for that level of prototype work, the tolerances are too tight for me to make the way I made my other ones. Double sided and very small traces, a lot of through holes that need plated etc.. My one design being a single sided board, with wider gaps on the traces, also the lack of solder mask. The other design being wider gaps yet between traces to help with the lack of solder mask and it is difficult to manually align both sides and get them transferred to the board properly. I also designed my double sided board specifically to having to use vias between the sides.

So, how did I come about making progress after eight months? Well in looking for some parts for my TI99/4a, I found the PCBs for the GAL PLA for sale at what I felt was a reasonable price and ordered two. It turned out to be a very easy project. Since it is a manufactured board, all it really amounted to was installing the pin headers for everything. Adrian used Machined Sockets for the GALs and Machined Pin headers for the legs, in my case I used Machined Pin Headers for everything. Beyond that I did the same thing as he had.

Keep in mind what order you want to solder the headers up. If you use sockets, then you must put the underside legs on first. If you use all Pin Headers like I did, I found it easiest to put on the inner pin headers for the GALs on the top side, then the lower “legs” and finished up with the outer pin headers for the GALs. It turned out great. I certainly do NOT recommend using the larger square pin headers.. They damage sockets badly as they are far to large. The “turned pin”/”machine/machined pin” headers can be problematic as well especially in old single wipe sockets.

The Left are “square” pin headers like on Arduino boards, rpi etc. The right though is the machined pin headers

Above you can see the more popular Square Pin Headers. Those are not what should be used for the legs, you should use the Machined Pins instead. These are for the legs, the shorter pins going into the circuit board and soldered on there. The longer legs sticking down and those insert in the IC Sockets on the mainboard.

Machine Pin Sockets. I used these instead of IC Sockets for the GAL chips to insert into.

Above are the Machine Pin Sockets that I used in place of standard IC Sockets. I generally prefer Machine Pin Sockets to the single or double wipe standard ones. They machine type sockets are more flexible than standard sockets as they don’t go all the way into the PCB. These Machine Pin Headers though are almost identical to the Machine Pin IC Sockets, but can be made any required length. I didn’t have sockets of the size of these GAL chips so I used the headers. I also used these for the ATMEGA in my Pi1541, as I needed a Machine Pin Socket and the standard double wipe socket wouldn’t work on my homemade pcb.

The bottom with the round Machine Pin Headers.

A side note on the Machine Pin Headers and Machine Pin Sockets that I used. They fit together just like they are made for each other. With a little careful work and some heat shrink on the ends you can make them into inline connections for wiring. Sometimes it is useful like when I make lighting in models and such. They fit fairly well, it is a little like using those DUPONT Male and Female cables that use the “square” pins as seen further above. I think these kind of click in a little more securely, they also make a shorter connector in the end.

Unfortunately, before programing the GALs, I tried to program an EPROM for a cartridge I had assembled. A bit over half way through programming the EPROM the programmer failed, now it says it has a short of VCC problem, and fails the self test on the first VCC test.. That meant I had to order a new TL866ii Plus and wait on it to come in. I wasn’t very happy as I did not get very much use out of the first one even though I had it about a year and a half. I tried downloading the new software and putting on the lasted firmware, but the same result.. I have mostly given up on that programmer, but I certainly will keep it around incase I have an issue with the new one, or find a solution on repairing it.

The new programmer arrived the other day, and since I had the latest software and all the files already, it didn’t take long to program up the GALs. Still out of the 5 GALs two of them didn’t want to program successfully. I did program a pair then used the fifth one to start another set. I cleaned the legs on one of the two that didn’t want to program initially and it seemed to program properly that time around. I should have the chips ready to go for a second replacement if I need it in the future. I haven’t tried cleaning the other GAL and programming it again, I can’t do anything with just 1 GAL anyway at this point, but I did keep it incase I can get it working. I generally don’t do much during the week as far as pulling the Commodore apart so I didn’t test it until today.

GAL PLA Replacement installed. I like Sharpie Oil Paint Markers for marking stuff like this. Standard Sharpie fades or rubs off over time..

Here it is installed in one of my Commodore 64s. If you read my other posts on this one where I cleaned up and repaired it, you may know I have a PLAnkton PLA in it normally. I am just testing this one. The board has a Machined Socket installed in it already which properly accepts the Machined Pin Headers, which the PLAnkton actually has too. The PLA in my second Commodore 64 is also socketed, if memory serves (as about everything is socketed in it), but it has a the regular either single wipe or double wipe socket. Installing the round Machined Pin Headers into that may damage the socket. That Commodore 64 still has an original working PLA in it, if I damage the socket it may not make good contact. If the PLA had failed, I wouldn’t be so concerned. In this case though I am just testing that it works, so I know it is ready to go if needed. I doubt the PLAnkton will fail me anytime soon, but the factory PLA in the other 64 may. I am actually using the second Commodore 64 more than this first one.

Yes I also have an ARM SID in this Commodore, I found the SID that was in this one had an issue. It may have been damaged all along, or it may have been when I accidentally shorted some of the traces together. The original SID was directly installed into the mainboard, and the legs were never trimmed at the factory. That left them sticking through quite a bit, and having the board sitting on the workbench ended up folding them over onto traces, and cut into the solder mask causing a short. The ARM SID wasn’t cheap, but I felt it was the best replacement if I wanted full function SID in the board. I am quite happy with it so far, but I do need to get the firmware update installed which fixes some issues.

I did not do exhaustive testing of the GAL PLA, but I did some testing here with the Dead Test and a short run of the Diag cartridge without the harness before that. I let the Dead Test run 8 full cycles without any issues.

I certainly like how easy this worked out. It looks well modified, but fits very well and is nicely built. I don’t have Super Zaxxon or anything to really stress this out that I know of. I have reinstalled my PLAnkton and closed the ole girl up. The GAL PLA is going to be packed safely in some EDS conductive foam for a rainy day.

Below is a link for Adrian’s first video on the GAL PLA. He did a follow up testing the Epyx Fast load as well.

Thanks for reading. I hope something here is helpful. I do most of these posts to kind of pull together different sources and include little things that I came across in doing these projects that may not have been mentioned in the other source material that I had when doing the project. This was a quick and easy project even though I kind of started thinking about it quite a while ago.

Due to getting these boards in and a couple others, I have finally made a customized board that I have ordered from JLCPCB. I know I see a lot more advertisements for PCBWay. Maybe I would try them at some point. JLC seemed more strait forward to get the initial order in and seemed a bit cheaper. Provided those boards work out, I expect that I will be putting together a post on that project after they come in. I have worked on a few things that I haven’t gotten around to posting. Mostly simple stuff that doesn’t take much in the way of a post and may not be of much value to post.

In the end I really don’t like waiting on things, or I may have ordered some of these PCBs myself. Then of course I waited 9 months to find some that someone else went to the trouble to order…. It really showed me how easy it is to put together a simple project like this when you have a properly made PCB compared to trying to wire up some sort of adapter from Pin Headers or IC Sockets and jumper wires. My Pi1541 was very time consuming to build. Sure there was a good bit of planning and construction, but had I ordered in the PCB, it would have been so much easier to assemble. It would have also been a bit easier to design the board when I didn’t have to take into account making VIAs by hand, dealing with lack of solder mask etc.. The Pi1541/Tapuino board did initially have a number of mistakes, and that would have kind of sucked to have ordered in and have to fix that, but it would have been possible. The board is kind of specific too, I didn’t want 4-9 laying around forever either.. How many people want a Pi1541 the size of an original 1541 anyways? If I were to redo the project and it turned out possible to design it to be the proper layout and size to be a Pi Hat type but fit the original 1541, as well as maybe a break away Tapuino board section that could be stand alone.. I may have seen a use for more of the boards. That was far beyond ever doing with my hobby level board etching ability. I have since made a second Pi1541 (without a Tapuino), that one was a lot of hand wiring and would have been so much easier with a PCB or two.. Still what am I going to do with 5-10 of a board.. Most of my projects I only need one or two of.

Pi1541 in 1541 Case & Tapuino – Part 3 : Schematics and a bit

I wanted to post the final Schematics for the Pi1541 Option B+SRQ and Bare Tapuino here.

Gerber Files for the board can be downloaded from here:

Below is the Bare Tapuino schematic. It is basically a Tapuino using a bare ATMEGA328 instead of an Arduino Nano etc as the base. The ATMEGA is burned with the Arduino Uno boot loader. It can be programmed by pulling it or on the board. The required connections are available on the board by the Reset pin plus and other headers. That is why the Reset pin is there, to make that easier. I didn’t route a regular ICSP header though. It was hard enough to route this board for me, and I believe the other header with the required pins would have had to been unplugged for it to succeed. There has not been any firmware update for the Tapuino in a good while either. The design is a combination of the schematics from the Tapuino Github. The C2CON header is for the secondary Cassette for recording from it. I did not use that, although I do have the header in there on my board I have no connector anywhere to accomplish it. Because I am not using that feature, I really don’t need the 4052N on my board. That is what it is for. The 4052N can be bypassed by putting two jumpers in its place. The first jumper goes from Pin1 to Pin3 on it (Write Signal). The second bypass jumper goes from Pin12 to Pin13 (Read Signal). The Tapuino is a Tapuino 1.5 plus the Read and Write LEDs from the Tapuino Mini 1.02, and then using a bare Atmega instead of a Arduino Nano or Mini etc. I could not find schematics for the later Tapuino versions, I guess someone else made them to sell and has not released them. I didn’t care for a buzzer or speaker attached to hear the playback, so I was fine without that. I really do not have the Read or Write LEDs on my board at this time as they were added later. I might add them, but I am not sure it is worth the trouble. I would have to take my control panel apart to get them installed, my thought is to place some surface mount LEDs just behind the mesh. The other thing I would like is there was another firmware out there that had some “graphical” look to the Tapuino LCD display, I would really prefer that. I can’t find it anywhere, it was posted on a German blog I believe, but only pictures of it, no code etc.

The other note on the 4052N is that the 74HTC4052N does not work, but a 74HC4052N does work on the Tapuino.

Being a “Bareduino” base, there are other components on the schematic that are not typically on a Tapuino. That is because most are based on using one of the Arduino boards as a base. It was a good excuse for me to make a Bareduino.. I figured why waste an Arduino Nano or something like that if I was making a board anyways.

Pi5141 Option B + SRQ and TFT LCD Passthrough header.

The above is the Pi1541 Schematic. It is Option B plus with the addition of including the SRQ signals. They will be required for some updates to the firmware to take advantage of.

The TFT LCD Passthrough is probably less useful to most, it is actually a traditional Mini Din PS/2 Port. That is what my little 7″ Composite LCD came with as a connector. I decided to put it into the Tapuino. It was originally for use on my workbench to test my Commodore 64. It supports 2 inputs, the default is the one connected to the Pi’s Composite video output. The second input is out the back of the 1541 case and can be connected to the Commodore 64 Composite Video output. The board footprint and setup is actually setup so as to allow putting a Second Serial Din port side by side with the first one. If that was the case, then the TFTLCD header would be wired over to the back of the Serial port and the Serial Din would be installed instead of the PS/2 style Mini Din.

The 7″ LCD though lets me use this device as a stand alone device with the Pi, or with the Commodore as a reasonably portable LCD. There is also a jack on the back of the 1541 for an Audio Input with a switch beside it. If the switch is flipped toward the jack it will output the audio from the external jack to the internal amp and speakers, if it is switched the away from it then the audio is connected to the Pi’s audio output instead. This lets me play the Pi sounds through the internal speakers. The speakers are actually Mono, the rear jack is mono too. The Pi audio output is mixed down to mono with a resistor to prevent them back feeding into each other and damaging the Pi’s audio output. The alternate is that I can again connect up the Commodore 64’s Audio Output to the internal speakers.

The MicroSD Cards are both accessible from the front, the one on the left being the Pi’s card slot, which is extended with a MicroSD extender. The one on the right being the Tapuino’s card. This lets me remove them to add or remove files easily. The other thing it allows me is to swap the card in the Pi. I can then use the Pi for more things like running Raspbian on it, I can then output that to the internal speaker and the 7″ LCD. It can alternately access the HDMI Port on the side of the case (again with an extension going to the Pi itself). I can also put in a card with RetroPi on it, which again can run on the internal speaker and 7″ LCD or alternately output through the HDMI. I can then connect up controllers to the USB ports that are accessible on the side as well.

There are plenty of variations on the design possible. My point was to reuse this case I couldn’t otherwise make use of due to the failed read write head on the unit. The transformer I had left was for 220Volt input, so that wouldn’t have been of use to me either. I wanted to do something with it that would fit in with my C64, and there was just way to much extra space to not make more use of it. I liked the idea of doing a Bareduino project as well.

The Cassette cable worked out really well to. It is basically wired up as a passthrough Pin 1 to Pin 1 from the Din to the Card Edge connector. The Card Edge end is bolted into a DB15 (Gameport type not HD15 VGA (which is DB9 sized)) shell. I later painted it with a Green “Top” mark and lines and a Red “Bottom” mark so that I know which side should be up. I also inserted a bit of plastic to work as a Key into the slot in the connector. I had done that before and it fell out, so i wanted to have a visible mark as well. The wire is part of a very flexible Cat5 cable (yes old Cat5 not Cat5e) that I came across, I pulled out the extra 2 wires to make it more flexible as well. The ends have some heat shrink on them to build them up slightly and provide some strait relief.

Above you can see both the 7″ LCD and the little OLED on the drive face both display the Pi1541 output. So it can be used with or without the 7″ attached. The Pi controls are there on the left side, the 3 buttons and the 2 way momentary toggle switch. The Red LED is the Pi1541 activity light. The Green led on the left in the factory location is the Pi1541 power LED, it lets you know the Pi’s power is turned on. The other Green LED on the front panel is actually the Power LED for the internal audio amp. The Red tipped knob is the volume control and On/Off for the Audio Amp. The 4 buttons on the right are the Tapuino controls with the small LCD on the right being the Tapuino display. The Tapuino is powered completely by the Commodore 64 Cassette port. So the main power for the Pi does not need to be on for the Tapuino to work. That is partly why there are 2 schematics. There are two 5Volt power sources, the one that Pi uses is the internal Meanwell power supply where the Tapuino section receives the power it uses from the Cassette port, they are not wired together. They do share a common ground, which they share through Serial connection anyways.

I have used this unit for Raspbian as well as Retro Pie as well. My general intention is to use it just as a Pi1541 though most of the time. Originally I figured I would use it for Retro Pie a bit as well, but I have since built a Bartop Arcade to run Retro Pie instead. I really didn’t feel like disconnecting it from the Commodore desk and moving it to the living room to connect to the TV and such just to play some old games (other than Commodore games that is).

I have been thinking of putting a button on GPIO3 for a safe shutdown and startup button for the Pi when using Raspbian or Retropie like I did with my Bartop Arcade build. I just don’t at this time know where I would want to put the physical button. I could reuse one of the Pi1541 buttons, I could assign Safe Shutdown to another GPIO Pin that they happen to already be connected to. Still that would then not work as a wake up button as GPIO3 is the only one that will wake it.

Commodore 128 80 Column RGBI to SCART to HDMI.

I have been wanting to get a working display for the Commodore 128 80 Column mode. Looking into it, certainly get an old compatible CRT Monitor, either a Commodore RGBI monitor or apparently a CGA monitor potentially. Well they are old and they are expensive, and quite expensive to ship. There a couple more modern LCDs, including some NEC Multisync 70 series monitors. They are apparently around, but they are old and somewhat expensive too. If I get a display I would rather have confidence that it will last for a fair while. That and I am pretty cheap I guess.

I looked at options, the Monochrome Composite 80 Column mode is easy. Just make up a cable with the DB9 and a regular RCA plug on the other end. I want color though.

There are some CGA(RGBI) to VGA converters that people make to sell. They convert the Digital CGA signal to an Analog RGB signal, that is close to VGA. The frequency is at the CGA 15khz though instead of 31khz like VGA though. So most monitors don’t accept the 15khz signals (NEC Multisync 70 series is one of the few again, and the 60 series that I have doesn’t). Then you need a second unit that then takes that 15khz to a 31khz VGA signal.

I found a circuit design for a CGA/RGBI to Analog VGA. This is the first part, and you need a secondary converter to take the 15khz signal to the standard VGA 31khz. The GBS-8200 is a popular solution to take the signal to 15khz. I found another solution, which is a SCART to HDMI converter that Adrian Black posted about on his Youtube channel. I picked one up, an a donor cable to make up a proper cable for it.

I took the RGBI converter diagram and came up with a bit of a hybrid of it. I had tried an earlier wiring up to see if my Multisync 60 series monitor worked, it didn’t. So I am making up up circuit I found. There was a report by another site that said they didn’t like that circuit, and preferred another circuit for the process.

The draw back of these RGBI converters is that while they are full 16color output, they output Dark Yellow in place of Brown. It is not a fault of the circuit, it is because that is how CGA/RGBI worked, the Monitors actually handled the color replacement. To do the Dark Yellow to Brown replacement requires including the 74LS138N ic. When it gets the “Dark Yellow” signal, it injects just a little bit into the “Green” pushing the visual output from Dark Yellow to Brown through R1 below.

Update 2/5/23: Today I was looking to revise this project to a PCB Design. In looking at, it I and thought the Sync Invert was incorrect on the schematic. I was wrong, it was correct so I have switched the schematic back to the original from 2019. I have no promise I will complete a PCB design, but if I do I will be posting it up on Github or another site. I am thinking of making the pcb to fit into the same case I used for the prototype if possible. To make it more useful for IBM CGA I plan to put a power jack on it, the Commodore AV Port will be a pin header row or something, so it will be optional. There will be the optional Audio Jack coming from the Commodore AV Port, as well as an option for the Monochrome 80 Column Composite output (because I can), Commodore 40 Column Composite as well as Commodore 40 Column SVideo output. I am making the PCB Design in KiCad at this point. I want to see how that works. I had used Eagle back at the time of making this project initially. I have recently used EasyEDA as part of the Super Game Boy project, as Joe had build it in there. I wanted to see how KiCad compares. The schematic is nearly finished in KiCad, but the one in Eagle as seen below looks “neater”. I am finding some issues with KiCad not having footprints I would like to be ready to use, but we will see once I start having to work them out and find parts.

Progress on the 2023 PCB Design. See my other posts on the progress there. V1.3 files are now released, see “Part 4” post for the links.

Here are some pictures of the unit built up on some protoboard and reusing a section of board with a HD15 VGA connector on it. There are a couple of things I will be doing with the board, first I will be installing a 150 Ohm resistor on the board (R9). Currently in the second picture you can see an old 150 Ohm resistor in there for testing. I was making sure that 150 Ohms wasn’t too much and that it brings the current usage down to what I consider should be a safer level. Initially I had been using a higher value resistor and the circuit wouldn’t work. The SCART box needs enough voltage on Pin16 “Blanking” which switches it over from Composite Video to RGB Video mode. With too low a resistor I wasn’t happy with the current draw. I am going to be powering this board from the Commodore 128’s AV Port. I didn’t want to risk damaging the computer by pulling to much power through the port. With the 150 Ohm it had lowered it to a better level. The other changes I will be making also involve the AV Port connector. I want to be able to connect up for both 80 and 40 Column video modes, with the AV Port plugged into the box for power, I can’t get to the 40 Column signals. I am going to add another RCA jack for the Composite Video, I will also add a SVideo port somehow later on, so that will be an option for 40 Column mode. The a RCA port was the Audio out coming in from the AV Port originally when the first pictures were taken (in the end I moved the Audio to the side, and made that port 40 Column Composite Video). The Audio also goes into the “vga” jack and is sent to the SCART converter to go into the HDMI signal from it. I could have hard wired in the SCART Cable instead of including the VGA port. I wanted to give myself other options with the box though. That is also why there are some jumpers on the schematic. They are there on the board, but they are not easy to see as they are a bit under the wires in the pictures below. The jumpers can allow to switch from Combined Sync mode (CSync), to the VGA Split Sync (HSync & VSync). The second Jumper is the Inverter jumper for CSync/HSync line, with it one way the CSync is inverted, with it the other way it is not inverted. This gives options to potentially connect to other devices, like the GBS8200, maybe some Multi Sync VGA monitor if I come across one. The only concern I have with either of them, is that I am sending Audio to the VGA port to Pin 4. If the Monitor or the GBS board do anything with Pin4 they could damage the SID or be damaged themselves. The other alteration on the VGA pin out is Pin 9 has the “Blanking” voltage wired into it, old VGA cards (very old I guess) sometimes had a 5Volt output on that pin, so as I am feeding it with something under 5Volts it shouldn’t do anything, but that doesn’t mean something won’t be wired to it. I have seen diagrams of people thinking Pin 9 on the VGA port should be Grounded, which that would be bad.. certainly it wouldn’t be a good thing to do.

So after a lot of checking of my wiring, I finally connected it up to the Commodore 128, and well it worked. That was great because I couldn’t get it to work 100% on the breadboard. I though the issue might be the variation of the XOR Gate IC I was using, so I had ordered in some replacements, so it was either that or all of the slop of the breadboard wiring. There is that “Saturn’s Rings” looking interference there going across centered around the Light Blue line. That was a visible thing on the display. I didn’t have that specific issue in the breadboard circuit. The point to point wiring isn’t the best either, so maybe that has something to do with it. I have yet to try it on another monitor though. Still I am pretty happy with it, and soon I will be able to close the box up and make use of the 80 Column mode when I want to. The color correction on the Brown seems to be working, the text at the top is in “brown”. At the least I can say it looks closer to Brown than Dark Yellow to me. The other colors look reasonable to me as well.


Below here is the SCART to HDMI Converter I am using. I found it on a video by Adrian Black where he was recommending this model specifically over the other similar priced models. He said that Heatsinks needed applied to the two chips inside though.

Below you can see the two heatsinks I installed. I hope they are enough, the little one in the lower right is fine, but the main chip heatsink is smaller than the one Adrian was using. I don’t know how hot these get with use. If they “sort of work” without them, I would hope that they will be just fine with these. They are the type that come with some 3m tape applied.

Two Heatsinks Installed for reliably.

Above I have put together a diagram of the Output of the circuit I built and how it is wired to the VGA port and then how that wires over to the SCART Cable. For a GBS8200 or proper Multi Sync VGA monitor you would just use a regular VGA Cable. I would feel better if you used a minimal VGA cable, which is R,G,B, Ground, C Sync/H Sync and V Sync. I find that the thin modern VGA cables now only have those wires in them. I have had older ones that were about as small but did have all of the wires in them. I am putting in a jumper to disconnect the Audio from the VGA port for safety. When the jumper is moved to the other position the audio then goes to the RCA port on the side (the Red one not the Yellow one).

Here is the Analog RGB side. The RCA port there is now wired to the
Commodore AV Port Composite Video (40 column output). I painted it yellow to reflect what it is.
Here is a top view once it was finished. The Additional RCA on the side is now wired to the Audio Out from the SID via the Commodore AV port and is Red to reflect it is an Audio port. Below you will see an additional “jumper” that is not on the schematic labeled “<Audio” that is a 2 position jumper that either passes the Audio to the “VGA” port or to the Red RCA Port depending on the position it is set to.
Above I put on text for the 4 jumper locations and functions. SCART blanking is connected or disonnected, Audio is to the VGA Pin4 or to the Side RCA. Then CSync Inverter or non inverting. Finally CSync or HSync (such as if I had a compatible MultiSync Vga Monitor)

I certainly look forward to using this setup for my Commodore 128. I added the label below, it is printed on an inkjet printer with standard paper. I then used some tape to mask off the top of the box, and sprayed it with Locktite Spray Adhesive 200 Middleweight bonding spray. I let it slightly dry before putting the paper inplace so that it would not bleed into the paper. It is sticking perfectly, I guess I will see how long it holds up. I may have put some clear packing tape over it before cutting it out, but I didn’t have any. I have used the process for some cartridge labels as well.

A few References:!msg/comp.sys.cbm/ARbaCb8n9Sg/B0UPWvrKOaUJ

Nothing above is exactly what I ended up with, but that is what I based my converter off of. I used H2Obesssion’s CSync and SCART info, and then the other for the Digital to Analog and Brown fix. I would really have liked H2Obession’s “Ultimate” circuit to have worked out. There were reasons it did not work in my case, mostly I think it was the SCART Blanking. If I make another, I was thinking of trying it again.

The unit does work for me, it may not startup the Sync signal quickly enough and I have to reset the Commodore 128 to get the display to show.

The design can be adapted for IBM CGA use. The only difference there is the source of the 5Volt power as there is no Commodore AV port to supply it. Certainly a DC power jack could be added instead for a 5Volt DC power input.

The Computer Saver (C64 Saver)

Ray Carlsen created a protection circuit for the 5Volt DC line on the Commodore 64 computers, as well it can be used for other Commodore computers and other units that use a 5Volt DC input. The Commodore 64 power supplies supply both an unregulated 9Volts AC and a regulated 5Volts DC supply. The old 5Volt Regulators tend to fail and just quit regulating, causing the full power to goto the Commodore Computer, which can’t handle more than 5.5V input. When at 5.5Volts that is the maximum voltage the Commodore 64 Ram chips are designed to handle. The circuit is designed to cut power to the computer if the power goes to 5.4Volts or higher. Ray custom selects his components to get the proper fixed trip point. sells a kit that includes the components to build one of these circuits. Ray Carlsen also sells his as built calibrated units. The one thing is that the 5.4Volt cut off wouldn’t be ensured suing the Console5 kit. Ray mentions adding some additional resistors to fine tune it when building the circuit. I don’t know how far off it may be without doing the tuning. I took Console5’s diagram and compared it to Ray’s. Ray had since added a capacitor on the one transistor as well as a 220k resistor that were not on his schematics. With that information I decided to come up with a circuit board design using Console5’s kit that I picked up. I was able to find the Relay footprint in Eagle. I could not find the Fuse footprint though. I ended up modifying a footprint from a 20mm fuse to match up the 15mm version to. I think I got that right.

Here is the revised schematic. C1 is the added capacitor. R8 is the added 220k Resistor. I have replaced R6 with a multi-turn trimpot in the diagram, it is for fine tuning the calibration of the trip point to 5.4 Volts. This is NOT the exact diagram that was used for the prototype circuit board in the pictures.
Here is the revised circuit board layout. It has C1 and R8 as well as the Trimpot for the voltage adjustment. Below in the pictures you will see C1 is present, R8 is not, and instead of the trimpot I have paired some spots for regular resistors.

After coming up with what I hope to be a proper layout. I started to try to make the board. I had been on the lookout for a potential printer to use for Toner Transfer PCB work. I came across a HP LaserJet P2015dn. It was quite dirty, and the toner was low, but it was printing. I had been tossing around the idea of buying a new cheap laser printer, and I am glad I didn’t as I was looking at a Brother laser printer and they apparently can’t be used for toner transfer due to the higher melting temperature of their toner.

So I started off cutting down a piece of circuit board material.

Here I scored a line with a utility knife and square.

This board is a piece I picked up back over 20 years ago at school. It was old stock then.. It is very thick and very strong fiberglass based board.

After first marking it, I put it in my vice and scored the back side a little as well as the front deeper.
Here I folded it back. I was a bit impatient, and it was a very hard and high quality board. It took a good bit to snap it off.

After breaking the thin strip off I cut that down in half again. Then I sanded the surface to get any tarnish off. Any tarnish will prevent etching, or mess with it atleast. It can also make the toner not attach properly. Then I cleaned it with some IPA to get any residue off as well as any oils that may prevent the toner transfer.

Next I then split it down in half length wise as well. That was a bit easier. I then sanded the surface down to remove any oxidation. I then used a bit of 91% IPA to clean any oils.

Next I taped the cut out print to the board.

Here is wrapped the board with the print out.
Here you see the back side. No this is not the copper side.

Here we see the final result. Well I knew the toner was low and the printout very light. Due to that fact I was quite happy to get as good as I did. I wasn’t seeing any distortions, or smearing the toner. I was really testing if I could do it at all with the toner and iron. A trick to using the Iron is you aren’t trying to make the iron as hot as you can. You are trying to make it hot enough, but not so that it completely liqufies the toner. When it does that it smears it around and bleeds etc. So the other thing is that pressure has alot to do with it. I picked up a small sturdy iron ( I hope it is sturdy, it looks to be) that I could put a lot of weight on.

Well it didn’t work out. The toner was too low in the printer mostly.

Since that went pretty well overall considering the toner level. I figured I would risk a new toner for this very old HP Laserjet. I picked up a cheap aftermarket one, it worked and was better than the empty one, but the toner is not quite 100%. I also tried printing on a glossy magazine page. Both worked great, the print was great, very dark and clear. The paper took the toner well.

Here I started over with a new toner cartridge. This time using a glossy page from a magazine instead of the expensive toner transfer paper.

I prepared the other sample board, again sanding to polish it clean and IPA to clean it. I then cut out and wrapped the board wit the print out. There you can see the setting I used on the iron, a little past half way. I had read about iron temps, and used an ir thermometer to check the temp of the iron to get something close to what was recommended in a post I was reading over. I have a piece of old mdf or some fiber board there, then a smooth light blue painted aluminum plate that I placed on my workbench to iron the board with. First I let the iron heat up, then I set it on the board for a minute. I then put as much of my full weight on the iron for about 30 seconds (per the instructions I was following). I then applied heat and pressure to the board moving the iron around for another minute and a half or so. Then the board was placed in a bowl of cold water to get the magazine paper to break down to be easy to remove without pealing off the toner. I found the magazine paper to remove very easily, the expensive toner transfer paper doesn’t do that. You can see the first board and this second test here as well. The main issue I had was keeping the board from sliding around. I have some silicon thimbles (well that is what they look like), and put one on a finger to help me hold it without burning myself too much. The silicon does help alot, but doesn’t stop all of the heat so be careful. I actually use them when soldering, they also help with the heat there, but there you also can still get too much heat through if you aren’t careful.

Here is the little iron I picked up for this usage. It is small, which may be a problem with a bigger board. But I can put a lot of pressure on it with it’s design.

Here on the top you can see the new board. It came out almost perfect from what I could tell. Only about 3 minutes to transfer this design was great.

Now that new top board looks much better. There were two nicks in the print, the one on the outer marker line on the top and that little spec on the ground plane around the middle of the bottom. The spec was missing from the printout as seen above though.

My method of etching a board is based on a post I read about using Peroxide, Vinegar and a bit of Salt. I have this stuff around, it seems to likely be safer than other methods. Cleanup is easy. It is slower. I doesn’t see how it is as fast as the author said, but it does seem to work. 2 to 3 ratio of Peroxide and Vinegar, plus a fair measure of salt (enough to keep the solution green instead of blue). When it goes blue it will pretty much stop, but if the salt is added and it goes green that pulls out some of the copper from being reabsorbed into the solution basically. This is a very small board, and I have a nearly full ground plane, so the solution didn’t change color, at least that I could see in the dark here. Yes I etch it outside for safety and I don’t know what fumes come off of it if they may corrode other metal nearby. Here yo can see the reaction and that yes the copper went green from it.

Here is the board after I took it out. Just a little before I took it out, I scrubbed it with an old toothbrush and some of the toner started to come off. I could see a trace with some copper in the area that needed removed, so I put it in for a short time anyways. The copper is fairly thick on this board, and it was only a tiny bit longer. It did cause tarnish in those exposed areas.

Here is the etched board, you can see where the toner started to fail. Real HP Toner may have held up a little better.

Here is the board after cleaning with some acetone and then a light sanding again to remove the bulk of the tarnish. What is left should not hurt anything. I will inspect the board that everything is etched enough and no shorts are there. You can see that little gap at the bottom on the outline. That was that little bit that didn’t transfer. I did touch up the other mark on the top where that spec was missing with a Sharpie before etching.

Some areas do look pretty close, but it is late and I am going to get some sleep. I will be looking at this tomorrow hopefully. Then if any bridges are found I will see about clearing them up and drilling the holes for the components. I am afraid solder bridging will be an issue. Those gaps between the traces are not that big. The picture above looks to be a bout double size to the real thing when compared on my monitor. It might not be the most fun to solder. If I had made the gaps wider, it may have been hard to keep a good ground path to everything, but I could see if that could be tweaked a bit. Still I only have 1 kit here and I don’t see why I would be etching another.

If anyone wants a copy of the design let me know. The custom thing is the library that has the fuse holder on it.. I don’t know how to to share that out. I guess I could put the board files on Github or something?

Console5 Kit:

Ray Carlsen’s pages:

Toner Transfer Post:

Etching Post:

Of course after I finished the board, I found Ray had added a 220k Resistor (R8 which is on the revised layout and schematic). Well I will see about adding it in, but for my current board it would be a bodge wiring bit to get it in there for this initial test board.

I decided I had so much time in this board, and it was close enough that I could still build it and see what I came up with.

First I checked for any shorts across any of the traces, and everything checked out there. Next I moved on to using the Drill Press to put in the holes. There are several sizes of holes, all quite small. The largest size, for the Fuse Holder and Relay did fit in my drill press, although it nearly didn’t get tight. The next couple smaller sizes wouldn’t get gripped by my drill press. So I took the bottom off of my metal Pinvise Drill and put it in the chuck, I left the other size piece inside it to provide some extra support to help reduce the chances I would crush the tube. I tried to put just enough pressure on it to keep it from slipping as to help reduce the chances of damaging my pin vice. It did work out, and there was no real damage to it in the end thankfully.

Drilled board.
Here it is completed, the mounting holes are a bit too close to the circuit though. You can see there are several sizes of holes.

Next I tinned all the copper and used some solder wick to grab up any bridged areas. Then I retested for shorts and corrected one created by the solder. I next went on to test fix the Fuse Holder and Relay, they fit perfectly. I removed them and started soldering in the lowest components first. That was the Zener Diode and the other Diode. Next I worked on the Standup resistors, transistors and capacitor. Then I did the four 2pin headers, the input, output and two LEDs. I don’t want the LEDs on the board. I did not set them up as Pin Headers though, so while the holes were properly spaced being 3mm LED pads, the holes were too small. I do have some “pin type” header pins, that on the bottom side are smaller round pins and not square the whole way through. I used those. Finally once everything else was installed I went on and did the Fuse Holder and the Relay. As I went I kept checking for solder bridges, and it was a bit of an issue without the solder mask as I expected. My next board I will see about leaving a larger gap on the ground plane.

Bottom side finished. It was not the easiest to work with a board like this with such close traces it liked to get solder bridges a lot.
Here is the top side completed. You can see the two points for the adjusting resistors. I need those too as it is flipping way to early.

So I tested it out and it it throwing at 4.76Volts. That is way to early. I was concerned with the resistor values being matched at 470Ohms when Ray’s was not matching resistors. That and Ray’s mention to have those secondary ones to help adjust it. Changing the one would change the trip point up and changing the other the trip point down. In reality the two will both go both ways, if the one is set higher then it will push it one way then if it is lower it will go the other way. I guess having both makes it more flexible based on what it needed to get it right to the 5.4Volt trip point using common resistor values. So I will work on that later to get it tuned in and see what it takes.

After further testing, I found it about impossible to get the trip point set with the resistor values on hand. I resorted to using a mini potentiometer, that let me set the trip point. I put it in the circuit at R6. After doing that I found that the trip point wasn’t remaining stable. I took a long break from it as I was quite disappointed in it. I have finally went back to look at the circuit again. I had someone ask about a C64 power supply, and well I happen to need to build a second supply myself for another C64 I have since purchased and repaired. So tonight I revisited this circuit.

I did some more searching on the circuit, and found a Github project with a board design for the Saver Circuit. “OpenC64Saver”. Looking at it, it is Ray’s diagram with the 220k and the capacitor included. The only change they made seems to be swapping the one resistor for a multi turn trimpot like I had ended up wanting to do. Although my board only fit a single turn mini pot on it. I like the layout, but I don’t have Kicad loaded to be able to look at the board design except their rendering. The footprint seems to be the same footprint as the Console 5 kit includes. The resistor values are different I believe, and a few other components. It could be a good start though to get one of those boards and the Console 5 kit.

So I looked at my prototype again. It was still being unstable. I got to thinking, I wonder if putting a load on the output would help? By adding a small load to the output (150Ohm Resistor, should be about 36mA so not much of a load), it has apparently fixed the stability issues. I have had it running for over half an hour now and it started out set to 5.41V as the trip point, now after being warmed up, it is occasionally tripping at 5.38V but so far solid on at 5.37V. I say that is close enough to being 5.4V trip and being stable. Granted I wouldn’t use this board as built, the single turn pot can accidentally slip or get changed without warning, maybe even by dropping or such.. So I would want at least to have a multi-turn in there instead. I am also not certain that the traces on the board are heavy enough to handle the current required to power the c64 and any cartridges or other items that may be plugged into it. They possibly are, but I think if I were to use this, I would want to make up a new board with the revised layout at the top of this post, or just make the OpenC64Saver board.

Commodore 64 Breadbin #2 Referb : 326298 Part 4 Finish up.

So I had to look into the keyboard issue with the * key. When opening the keyboard quickly get the shift lock desoldered. I have heard people tend to melt and ruin the switches. I had no issues with this one twice though I was very quick with removal and re soldering it. While I was in there I pulled out the two reworked plungers.

Above is the * key pressed, it is showing about 1.6k right there, but it varied above 2k, and if pressed really hard, it went down to around 700 Ohms. When pressed very hard it did register enough to work (sometimes).

Here is an example of another key that was working. around 125 Ohms with an easy press. I desoldered the Shift lock key, quickly as mentioned above, get it heated, and pull the wires and get the heat off of it. Then the removal of the screws again as before. Looking at the board and the plungers, I found the * key plunger had all kinds of white specks of dust of some type on it. I cleaned it off as best I could. The other keys didn’t seem to have the issue. I swapped that plunger over to the “British Pound” key, as I don’t expect to use that key much. I then installed the two replacements I had one going to the * key. I reassembled and then did the test on the * key again, and this time I got 70 Ohms, so that new plunger is working pretty good. I then reconnected it to the Commodore 64 and tested it. The keys were working, the “British Pound” key wasn’t as responsive as the rest, so the conductive pad on it must not be in the best condition, so it was good I moved it.

I did the “Soft press Restore” fix as well. The Capacitor Kit I purchased from includes a replacement Capacitor for C38. From the site ” includes a 4.7nF capacitor for C38.  Exchanging the factory 51pF for this 4.7nF capacitor returns soft-touch function to the RESTORE key. “

I had not intially put it in, I didn’t know what that modifcation did actually. So I looked it up, and it appears to be a good idea to have. Without the fix, the Restore key needs to be pressed hard and fast to get it to register. This is because the way the circuit wired to it works, it is not looking for a press, it is looking for a specific change that is a bit more digital. So it can miss a simple press, the hard press causing the switch in the button to “bounce” a number of times and one of those bounces tends to then register with the computer. It is a simple enough fix to do. That was the last bit I needed to do inside the case.

Next I put the keyboard back in the case, and installed the new plates and reinstalled the LED.

It turned out looking much better than it did originally. It is painted, so I will see how well that wears on it over time. The new badges look very good, they are thicker than the factory ones. The factory ones are about flush with the ridges around them, these are up out of the ridges a little bit. It is the special Gold remade badges. I think it looks neat, I guess it could have been about as good with the standard badges.

Below here is my stock 64. It has yellowed/browned a little bit, but it doesn’t look too bad to me. The new paint is lighter than the other unit, and I think it overall is a little light, but it is a fairly good match I think.

Well I now have the two working C64s. I guess I will need to make a second power supply sometime. I have the parts for it except the case at this time. I guess it is time to move on to another project.

I would love to hear it if anyone knows anything about the 8Pin Video mod that this had received in the past. If there is any information out there as to how it was done. Certainly removing the original port, drilling for the new one. Cutting a few traces around it to separate the additional pins. Then there are the 2 wires that were added in. I am wondering if there would be anything else involved. I think there were probably two changes in the VIC II area, but I don’t know if they are related or not. I also wonder why this board doesn’t have R36, when I have seen others that do, and a few other changes. There seem to be a lot of variations, and I wonder if some of them are recommended fixes done by the service centers to fix issues with the systems, or make them more reliable?

After finally putting it together, I noticed the power LED had quit working. The lead broke off the bottom of the LED, so I ended up replacing it with another vintage used Red LED from my parts bin. Thankfully it looks the same as the original even when lit up. A new modern Red LED would have likely been a fair bit brighter.

There is a note that the Reset Circuit relation to the 556 IC is different on this specific model of board. The schematics are not correct for it, unless there are correct ones somewhere that I have yet to find. This means that the Reset button on cartridges like the Final Cartridge iii etc don’t work. As well as on the User and Serial ports etc. I may look into modifying the board so that will work. I want to do it in such as way that I don’t have to cut traces on the board though. That is why R36 is missing, it is normally the pull up resistor on the Reset line, where in this setup it is not used and only the 556 is.