Commodore 64 C 250469 / 252311 Rev B

After building the RAD REU for my Commodore 64/128 I found out that the Nuvie videos were made for PAL systems. My two Commodore 64s and 128 are NTSC models. I didn’t make the RAD REU to watch those, but since I wanted to see what they were like. I started to look around for a reasonably priced PAL C64. I came across this one listed as not working with a switch issue at least. It also doesn’t look great.

It arrived with a little paint on the lower left corner, some cut marks along the lower case and badge. Such as hobby knife or pocket knife. The cuts look intentional, but I don’t see a reason or pattern. The case overall looked reasonable. I opened it up to inspect the stuck switch and overall condition. It was rather dirty inside, the cartridge port guard was somewhat rusted. A little rust on the RF Module. It was dirty like it been stored in an attic or shed. I tested the jammed switch and got it to move to a position where it was switched on. Powering it up the system seemed to work fine. I did some testing but not a full diagnostic test.

I took the system apart to clean it and work on the power switch.

The C64c after repairing the power switch and cleaning the board up.

This is a Short Board. I find it interesting how much less complex it is than my other two Commodore 64s.

I do have some brand new power switches for the C64, but these switches can be taken apart and be fixed, at least sometimes. I removed the power switch and took it apart, the grease in it was gummy and sticky making it not operate properly. The switch didn’t show any significant wear internally. It did take a fair bit to get the gummed up grease out of it though. I added new silicone grease and reassembled it. This blue power switch doesn’t have a “nice click” to it like my other Commodores, but as far as I can tell, it is working properly. It now moves nicely, and makes very good connection across the switch pins. I have since seen someone comment in a video that the Blue switch doesn’t feel or sound the same as the other Red ones, so it seems this is just one of those other types.

This got the computer working fully, or appeared to. While I had the board out, I did clean it with IPA. I cleaned as much of the rust from the cartridge shield as I could. I did not reinstall the clip on cardboard RF Shield. The image above is the board after cleaning and fixing the power switch.

For the case I washed it with dish soap and warm water. For the white paint on the case, I used 91% ipa, which easily removed it. For the cuts into the case, they were shallow, but I could “feel” the edges when touching them. I decided to use a hard plastic stick, and “rub/burnish” the scratch down. That pushed the raised up sides of the scratch back down and made it so that I couldn’t feel it any longer. There were a number of them all mostly below the keyboard. This also made them less visible, although if you look closely you can see them. The case is in good condition overall beyond that, the clips are intact, it is not cracked or modified.

Those are the scratches after burnishing them.

I also disassembled the keyboard, just taking the keys and springs off with a keycap puller. The rest of the keyboard assembly was cleaned with Windex, a brush, and qtips and paper towels. The keyboard frame and pcb was not disassembled, I waited to test it before deciding if it needed opened. The keys were washed with warm water, dish soap and a toothbrush. There were some springs that were a bit rusty, those spring were wiped down and put into a small cup of vinegar for about 20 minutes. They were then rinsed with water, wiped down and dried. The next day after the keys were properly dry, I reassembled the keyboard. It was connected to the computer and tested and found to be working properly.

The video output on the C64c was good on Composite. There are some visible jailbars, but it is not awful. I had more of TheRetroChannel’s RF Replacement boards for the C64Shortboard (and C128) as I installed one on my Commodore 128. I also had all the parts to build one, so I decided I would swap out the RF Module. With doing something like that, I decided I would also recap the board.

The audio jack on the board was modified to sit lower to the pcb. The jack would have otherwise been centered at the same point as the SVideo port. With the audio jack lowered, I was able to keep the board a little bit more level than I would have been able to otherwise. There is no modification to the C64 mainboard or case for this mod. The L-H opening is not modified and neither is the RF opening. I kept the modulator, just incase I want to put it back someday. To get proper alignment, I test fit in the board and case. Once I get the alignment correct, I solder in one of the 4 mounting pins, then test fit it again. Then solder the next mounting pin and test fit again. Then finally I solder the remaining two mounting pins as well as the 8 pins for the signals to finish the installation. I then tested output of the Composite video, it looks pretty much the same as before. I then tested the Svideo output and audio output, which both worked properly. The Svideo is sharper as expected. Also the Chroma/Luma is still on the normal display port as well as Composite video. There is a jumper on the new board that does disable the color signal to the Composite, which is to clean up the Svideo output a little, but I keep it installed. There is also the Chroma Luma bypass option, which I did not do. The board supports doing Stereo Audio out to the audio jack if you have dual SIDs, which I don’t have. It also has a Hard Reset circuit on it, that you either install a button in place of the Audio Jack or use a button mounted somewhere else by the one jumper header on it. At this time, I do not have the Hard Reset connected, but I did populate that part of the board incase I decide to set that up at some point. I don’t like to modify cases, so I don’t have anywhere to put a switch at this time.

The video wasn’t bad on this C64c, and after the change, the Composite looks pretty much the same. With the Commodore 128 there was a significant video output improvement though. I wouldn’t have put the mod, except I had the spare boards. It may be a little better, and it does make it easy to connect to SVideo. I do have a single Commodore 64 to Svideo cable, but I have 4 computers now, so not having to have more custom made cables around is nice if I want more than one of them connected at a time.

When I recap a board, I test the new capacitors before installing them. I then test the replaced capacitors and compare them to the new test results. With this computer, I didn’t find any capacitors that were obviously going out. Sometimes I find a few that seem to be out of where they were expected. I work to use proper replacements from good manufactures and sources. I see no reason these capacitors should fail as long as I have use for the computer. The old capacitors are 33 years old now, they may not have held up at some point in the future. My hand isn’t as steady as it was, and I can’t see the part as well as in the past. I can do this work now, I don’t know about in another 10-20 years what it would be like. Maybe the computer won’t work in that time, maybe it will..

I keep forgetting to get good before pictures of projects. There wasn’t much to this, I would have liked to have some pictures of the switch internals. I have been doing similar switch tear downs for years, it isn’t complex, although it is good to carefully look at the parts and how they come apart. The recap was standard, this board did give me a hard time with the thick ground plane though. I don’t remember having quite as much trouble with the other two C64s or the C128 on the ground plane. The cleaning is standard, I used dish soap and warm water in the bathtub for the case top and bottom. For the keycaps I use a bucket of warm water with dish soap in it. If I am not washing something large like the case in a sink/tub I will often use Windex instead. For sticker residue I use WD40. I only use IPA to get marks off if nothing else has worked, I also tend to not use it on dark plastic. IPA can damage the finish of some plastics and can make visible marks on dark plastics sometimes. I use IPA to clean circuit boards and metal areas. I have also started to use 99% IPA instead of the 70% or even 91% IPA to clean flux. That has shown to leave less residue, and break down flux much easier.

The RAD REU Nuvies do work with this PAL C64c. Now to get Sam’s Journey? Which is one of the reasons I wanted a REU to start..

Someday I may try to retrobright the keyboard. The case itself is not very yellow, but the keys are.

RAD Expansion Unit for Commodore 64/128

I have wanted a REU for my Commodore 64 and 128, but they haven’t been reasonable to get an original. I also has not seen a reproduction option. Yes there are a few options, but nothing I was going to get into. I recently came across Frntc’s RAD Expansion Unit Project. I recently saw the Sidekick64 and had been wondering what it was, what advantage does it have to other similar products. It turns out in the US you can’t buy built versions of his projects (short of shipping and fees from Europe). If you are in Europe there are authorized resellers of the RAD Expansion Unit.

The RAD REU uses a Raspberry pi, either a Pi3A+/B+ or Pi Zero2 to emulate a REU / Ram Expansion Unit. It can work at various sizes up to 16Mb, it can also work as Georam. It can do REU Images, which I am not familiar with, and NUVIEs and says it can run PRG. I take it the PRG is normal PRG files. NUVIEs are 16mb movie files which I have not tried. My intention for this device is to use it as a REU to run some programs I couldn’t otherwise run on my Commodore 64 / 128. I am thinking of trying out Geos as well with it.

Frntc has released the Gerber files for getting PCBs produced. It is highly recommended to get the Gold Plated ENIG boards. While the HASL Solder coated fingers are very common, they are common because they are cheap, not because they are recommended. Most or even all of the aftermarket Cartridges I have are HASL, they generally work, but use of them makes the solder rub off into your cartridge slot and will cause problems over time. The boards I had produced awhile ago were also HASL. I hadn’t been having issues with them on my C64, but I don’t swap cartridges often. I did find my C128 was very unreliable using the cartridges, which may be due to another reason.

I had a spare Pi3 A+, I do also have a single Pi Zero2, but I felt it is more useful for some other projects. I ordered up Frntc’s board design for the pi3 model with the Gold Plate ENIG board finish.

The gold looks very nice. It is a much more consistent finish on the edge connecter. I can see how these boards are certainly an upgrade for edge connector boards. For boards without the edge connector I will keep using the HASL finish. It is generally a difference for example from $2 to $19 for a small batch of boards.

Frntc provides a file called ibom.html in the Gerber folder that is an interactive Bill of Materials. It lists the basic part and footprint data for it. I wish he had used more universal footprints, some of these surface mount footprints can be setup to accept either the wider ics or the narrower ICs giving more valid part options. It took me awhile looking at the parts on Digikey and Mouser to find the ICs with the proper footprint for the boards.

I found all the right parts eventually. I was going to order from Digikey, but they didn’t have one of the ICs in stock. I went with Mouser as they had everything in stock. The pricing was close between the two suppliers. I did mess up and miss ordering some of things I had sitting in a cart at Digikey that I wanted to put on my next order though.. The parts all came in and it turns out everything was correct. I will list the specific Parts I ordered here.

1 Mouser #:771-74LVC245AD-T Mfr. #:74LVC245AD,118 Bus Transceivers 74LVC245AD/SOT163/SO20
2 Mouser #:595-SN74LVC573ADWR Mfr. #:SN74LVC573ADWR Octal Trans D-Type Latch
2 Mouser #:771-LVC257AD118 Mfr. #:74LVC257AD,118 74LVC257AD/SOT109/SO16
2 Mouser #:595-CD74HCT30M96 Mfr. #:CD74HCT30M96 CMOS Logic 8-Input NAND Gate
1 Mouser #:595-SN74CBTD3861DW Mfr. #:SN74CBTD3861DW 10bit FET w/Lvl Shft
2 Mouser #:611-PTS645VL832 Mfr. #:PTS645VL832LFS Tactile Switches
8 Mouser #:581-08055C104KMfr. #:08055C104KAT2A Capacitor 50V 0.1uF X7R 0805 10%
1 Mouser #:963-TMK212BBJ106MG-TMfr. #:TMK212BBJ106MG-T Capacitor 0805 25VDC 10uF 20% X5R
3 Mouser #:603-RC0805FR-0710KLMfr. #:RC0805FR-0710KL Resistor 10k Ohms 125 mW 0805 1%

Notes: The 10k Ohm resistors are 0805 parts not 603 an oddity in the part number I guess.. The Capacitors are all 0805 as well. One of the HTC30 ICs and it’s capacitor are not listed as required on the ibom. I found a picture of the board where that IC is outlined in the silkscreen as “optional”. I put them on, I wonder if it is for debugging or development? It was $0.45 in parts, so I didn’t see a reason to not install them.

I had an issue with the firmware. I figured it would be in the repository where it would download with it repository. That is how it has been for the few other projects that I have used. The code is in the repository if you download it, but not the compiled release. I am not very familiar with Github, maybe no one else will have an issue finding it without this little note. It turns out Releases are along the right hand side bar on Github. Since I had the issue finding it, I asked 8-bit Resurgence where the files were. So to get the compiled files, Click on “Releases” at the Github project page on the right hand bar, assuming they don’t change the location.

The soldering wasn’t too bad. I did try a new solder tip with the solder cavity in it for drag soldering. I found it was putting down to much solder and was difficult to remove a bridge with. I went back to my normal tip without the hollow in the bottom of it. I did use a paste flux, which I find is important for surface mount soldering, it helps clear and prevent bridges. I did find cleaning up the flux with 91% ipa wasn’t the easiest. It just didn’t do a great job and took a few passes. There was flux stuck inside the pi Header, you may be able to see it on the picture above still in the header. The next day I used contact cleaner on the header and ics. It flushed a lot of the flux out of the header, it also flushed a lot of flux out from under the ics that I didn’t know was still under there.

It works.

Now it needs a case. There is a case design linked with the project. I started printing it in a slightly translucent blue PLA. The label on it was printed on plain paper as a test with double sided tape on the back. Overall the case looked pretty good, it also fit well. I decided I wanted something that blended more with the Commodore 64.

I ordered in Polymaker Matte PLA 1.75mm Muted White Filament to see how that looked. It was recommended by the Macintosh Librarian as a good matching color for the early Macintosh. I figured it will not be a perfect color match, but it should be in a good color range to “fit in” better than the blue case.

I also had a small piece of Inkjet Vinyl. My old HP Inkjet printer is out of black ink, and the new color cartridge isn’t working well, probably due to how old it is even though I just installed it. It is also quite an old printer that Windows 10 doesn’t care to print to it properly. I had to tape the small piece to a piece of paper to put it through the printer. Which it did well with that. I’m debating buying fresh cartridges for it.

I like the new case a lot better. The label is much nicer too. I like the color, it is a light beige. It is not a “match” to the Commodore 64 Breadbin color, it is fairly close to the Commodore 128 or Commodore 64C. I can’t tell though, as my Commodore 128 is Yellow.. The Commodore 64 Breadbin I am using it in is lighter than the typical Breadbin because it has been Painted. The RAD REU is a bit lighter than the paint, but looks very nice with it. I did print the case at .28mm layer height, so printing at lower layer heights may make a little nicer looking case.

I have tried it with Nuvies as well, but the are almost exclusively PAL based, which won’t work on NTSC computers. I did then end up importing a PAL C64c, which is works well with and can play the PAL Nuvies.

Commodore 64 326298 Rev A 1982(FAB 326295 Rev D) Reset Mod and Switchless Kernal Mod

The Commodore 64 326298 Rev A has a different reset circuit. The 556 is wired in with a way that it keeps the reset line pulled to 5V and will supply as much current to that as it can. There are various ways to rework the circuit from over the years. I was looking at the least invasive way to accomplish this. I ran across a post on the Backbit Forum, as this reset being the way it is prevents the Backbit cartridge from working properly. It also affects other cartridges that use the Reset or have Reset buttons integrated into them. When they try to pull Reset to Ground the 556 works hard to keep it from resetting. It may crash the computer or cause glitches, probably as much as anything because it pulls the 5V line down starving the computer for power.

The process posted on the forum was to install a 1k Resistor in R36. This is a pull up resistor that keeps the Reset line pulled to 5V but “gently”. If it is missing the system could randomly reset, or be stuck in reset. The second part is to disconnect Pin9 on the 556 IC. We only want to disconnect the pin, the “wire” that is in the board there needs to remain connected. The simplest and easiest way to accomplish this would be to cut the leg off the 556. I didn’t want to do that.

What I ended up doing was desoldering the 556 from the board. I then took a 14pin machine pin IC Socket and clipped the bottom of Pin9 from it. I then paced he modified socket into the board so that Pin9 on the 556 is not going to the board. The Wire though is still going from the Pin9 Pad to Pin13 but that wire is no longer making contact with Pin9 of the 556. I then installed the 556 into the socket. On power on the system didn’t work. I checked the work, and then also tested the 556. The 556 had failed, it may have been during desoldering it, but it also may be that a portion of the 556 had been damaged by trying to use the Reset button on my cartridge. It may still have worked with Pin9 connected. I did have a spare so I tested the replacement and installed it. On powering it up the system worked normally again. I also tested using the reset button on the cartridge and that worked properly now. R36 is installed, it is a 1.5k resistor, a special precision one I have a small stock of, as I was short on 1k resistors at the time.

I believe if I had not done the Reset Modification that my next Modification, the Switchless Kernel ROM probably wouldn’t have worked normally. It also pulls Reset low, which it couldn’t sink all the current required to overcome the 556 previously.

C38 was previously replaced with a 4.7nF capacitor when I replaced the Electrolytic Capacitors to make the Restore key responsive. With the factory 51pF capacitor you have the hit the Restore key quite hard to get it to register usually, I don’t know if that would in any way affect the Kernal Switcher, as I haven’t seen it said that mod needs to be done. I did it as part of the recaping process based on it being recommended by Console5 where I purchased the kit. It did work as described, I tested both before and after switching that capacitor out.

Kernel Switcher:

The I am using bwak’s SKS64 “C64-Switchless-Multi-Kernal-27C256-adapter” project. This is a custom PCB that works as an adapter to install a 27256 as a 4 way Kernal ROM replacement. It is controlled with an ATTiny85, an early version used a PIC instead. I happened to have some ATTiny85s and liked the idea of using one for this. There are also ATMega based Arduino type board options out there. I am using a Pro Mini Arduino board for my Commodore 128 Switchless Kernal. This ATTiny was a neater solution for this, it is a all-in-one option as we already need an adapter board to convert the 27256 to work with the Commodore 64.

It has very good documentation at his Github page. There are considerations on what order your solder the parts together. He does cover that in his documentation.

The one inner pin row and 8pin Socket must be installed first and flush cut to fit the main socket on the top. I feel it best to install the resistors before the top socket as well.

The documentation shows where you can tap into the required signals on the C64 mainboard. The Reset, Restore and EXRom lines. Keep in mind the images below are for the 326298 Rev A, the guide from bwak shows similar images of all the various board types for reference.

I preped the board putting in single angled pin headers for the three signals and replaced the old single wipe socket for the Kernal ic. Of course I messed up and used the only socket I had, which you can see in the picture is solid in the center so the ATTiny85 on the bottom of the adapter can’t go in place.. So I have to replace it again, this time with machine pin header strips, as I don’t have an appropriate machine pin or other hollowed out socket to put on the board.

Since I had the wrong socket, I had to use the Turn Pin socket strips.

Now that the socket problem is sorted, I can get the adapter installed.

Switcher with the required header wires.

I was glad I was able to use some premade dupont cables I had. They are actually all premade cables from my breadboard cables I have. For the LED cable I just swapped the single dupont plastic holder for a tripple holder. There is an issue with just using the stock Red LED, but for now it works.

Note: I quickly replaced the Stock Red LED with a RGB LED, while it worked and the pictures in this section are showing the wiring for that, you only had the LED on if it was in Kernal 1, so the computer didn’t give an indication on the case that the power was on. The code could be change to always keep the RED LED on and just blink, but I didn’t want to look into what that involved. I just went with swapping to the RGB LED as I had them anyways.

The documentation is a lacking information on making the file to program the Eprom. You can get information from bwak on doing similar things by looking at the documentation on his VersaCart project. I’ll cover some basics blow.

The 27c256 is a 32k Eprom that can hold four 8k Kernal ROMs. I program the Eprom with my TL866ii plus.

To prepare the bin file for the Eprom. I collected them all in the same folder. I am using the Stock Kernal for the first one, then JiffyDos from RetroInovations, MasterRom 64, and JaffyDos (customized JiffyDos). Taking those 4 files in a folder, then open a Command Prompt window and while in the folder with the files use the command below. This is for the exact filenames I had, so your do need to be sure to enter the filenames you have instead. The U4_32KuB.bin is the 32k bin file I will use with my TL866ii to program the 27c256 Eprom. The code below it all in 1 line, if it is wrapped to two or more lines when viewing this page keep that in mind.

copy /b kernal.901227-03.bin+JiffyDOS_C64_6.01.bin+MASTEROM64_V3.0.BIN+jaffydos.bin U4_32KuB.bin

I will say JaffyDOS was a bit annoying to create. I couldn’t find proper instructions on how to accomplish it. JaffyDOS is created with a Commodore 64 .prg. You need to run it from the Commodore 64 Vice Emulator. You answer some customization settings once you manage to get it mounted properly and get it to where it can find your “JiffyDOS_C64_6.01.bin” which it has to be able to access. Running it properly will then create the jaffydos.bin file in the same folder as “JiffyDOS_C64_6.01.bin” had been located in. I did find some apparently outdated and possibly incomplete instructions and fumbled through getting the prg in Vice and the folder where the JiffyDOS bin was.

Once you have the 32k bin it is a simple task to use the TL866ii to burn the data to the Eprom. I will not go into detail on that, it is easy to find instructions on using at TL866 to program an Eprom or EEprom etc.

So the next bit that was a bit lacking in the documentation is programming the ATTiny85. You need to setup the Arduino IDE to be able to use the ATTiny85, and use bwak’s files to compile the program file. bwak does cover that you need to disable the Reset pin on the ATTiny if you want to use the EXRom function which enables doing a Hard Reset rather than the standard “Soft” Reset, if you are just using the Arduino IDE to program the ATTiny, then I don’t know how you disable the Reset pin, I think one or more of the ATTiny board types can do that. The ATTiny core I use for Arduino apparently doesn’t, or doesn’t make it obvious how to to it. The main reason I expect is they don’t want it to be easy for you to accidentally doing it without knowing that you will no longer be able to program the ATTiny with the Arduino IDE you will then have to use a HV(High Voltage) Programmer. If you have a TL866ii, it is a HV Programmer, it can set the Reset disable fuse, and also enable reset again if needed as well. He does cover that in his document. I actually used the Arduino IDE to program the ATTiny85, then used the TL866ii Plus to disable the ATTiny’s Reset pin fuse. You can also use the TL866ii to upload the Hex file created by the Arduino IDE though, which is in bwak’s document.

For now I just have the Stock LED in place. I will have to finish wiring up a RGB LED so I can then see which ROM is enabled by looking at it. I was hoping it would just keep the standard LED enabled, maybe somewhere in the code there is an option to tell it to just use the RED LED, I didn’t notice it though. The board looks like it is intended to be alternately used with the Stock LED though.

Beyond the LED being off for all but the First ROM (the Stock ROM in my case) it is working great. I’ll get that LED wired up and installed shortly. I have the right RGB LED, I just didn’t get around to making it up initially, I really didn’t want to make it up. I may look at the Code and see if there is an option to change the LED output behavior it is about as easy to make up the RGB LED as it is to pull the chip and recompile the code.

Commodore 128 / Commodore 64 Shortboard RF Module Replacement

I have been unhappy with the regular 40 Column video output on my Commodore 128. Watching a video by TheRetroChannel on Youtube, I saw his RF Module replacement. I feel technically that is not the right thing to call these types of boards, they “replace” the RF Module, but they are not “Replacement RF Modules”. You loose the “RF” Output, this really isn’t an issue as not many people would likely want to ever connect up the Commodore 128/64 by RF to an old TV tuned to Channel 3/4.

He released the board designs on Github as open source projects. There are two versions the C64 Longboard and the C64 Shortboard/C128 versions. For the Commodore 128 I needed the short board version, so I ordered them from JLCPCB. This is specifically the board that fits the Commodore 64 Short Board and Commodore 128 as they share the same type of Modulator. He also made a Commodore 64 Long Board version, they are basically the same but the Long Board version is a bit larger pcb to fit the Long Board properly.

https://github.com/TheRetroChannel/C128-C64-Shortboard-RF-replacement

The boards have various options on them. I have populated everything except the C64 Hard Reset section. This is for a Commodore 128 after all, and it already has a reset button. That isn’t a Hard Reset though, but by the time I install this that also won’t be an option. It is indicated it may not work on the C128 though I don’t know if that is the case or not.

I put on the 500 Ohm Trimmer Pots rather than the default resistors. I had the exact parts in stock, and I have a fair quantity of them, I purchased them for some project, maybe even when I was working on the earlier RGBI Adapter builds years ago. I did set them to match the set resistors as a starting point. The center and “right” pin have to be set to the baseline value, 75 Ohm and 180 Ohm I believe. I don’t know if I will have to do any adjustments on them or not (they were perfect at those starting values), but I had them and it made sense to me to use them. I probably have more of those Trimmers than resistors of the correct values anyways. This whole board was populated with parts I had in stock, the Audio jack was salvaged, but everything else is new. It was neat having a project I had everything for.

It was a strait forward build, everything is labeled. The two capacitors are labeled on the bottom of the board instead of the top, that did have me almost putting them in the wrong locations. It is easy to transpose the positions when flipping something over. I know he mentioned he made is so that the parts would cover up most of the silk screen markings. When assembled it does look pretty nice too. The only other thing I did check which pins on the Trimmers needed the proper baseline resistance set on them, but that was easy. I picked the White boards as I thought it would look nice when installed as well. It won’t clash with the color of the C128 board, or look like some poor attempt to color match it.

I am going to start with the normal Chroma/Luma paths. I will test that everything is working properly there, then I plan to switch to the External Chroma/Luma lines. The whole reason I am doing this modification is to try to improve the poor video quality I get from the VIC 40 Column video output. My Commodore 64s have far superior Video Output to the C128.

I really don’t need the SVideo and 3.5mm Audio Jack output. I have my RGBI Video Adapter which already has level adjusted SVideo and the SVideo jack (which is why I had a spare SVideo jack in my stash of parts), plus the Audio Jack on it. It won’t hurt to have them. It was unclear as to if the Chroma/Luma output on the Commodore AV Port was still active, but looking at the Schematics and board itself it is still connected.

Again, it was an easy build. TheRetroChannel does say the hard part of this mod is removing the RF Modulator module from the C128/64 board. He is correct, I have removed three of them, and well it is not something I look forward to.

I desoldered the factory RF Modulator, and stuck in the new unit. I fit it without soldering. The pins helped hold it reasonably secure so it wasn’t sliding around. So I did a test fit, and put the board in the case to get it lined up to the openings properly.

You can see that it is crooked in relation to the board. This is due to the alignment of the holes in the case having the opening for the “switch” lower than the “RF” port opening. Once I had it set where I wanted it, I carefully removed the boards from the case. I then tacked some of the pins with a bit of solder. I fitted it back inside the case again to make sure it didn’t move. Then I removed it from the case again and finished soldering it in. It was not difficult to align the board, as the pins held it fairly firmly in place as there are 12 pins they gave enough friction to not have it flop around while I was lifting it out of the case or flipping it over to solder.

It is in and the pins are all cut down properly. It was time to test it. I wanted to get some pictures of the output before switching out the modulator, but I forgot.. I fully remember it was awful in comparison to both of my Commodore 64s even in SVideo output. I was hoping I had some pictures of testing the SVideo output when I built the new RGBI adapter. I didn’t take pictures of the SVideo output. It was still awful at the time..

There is a jumper on the board to enable the Composite video, I believe the Chroma line to it. If you are just going to use SVideo, having it disabled is to slightly improve the output. I forgot to install it and ended up with the first screen above, basically no color except the “noise” around the text. The second shot is the Composite after putting the Jumper on. The last being SVideo output. The SVideo is much cleaner with no noise around the text. Even the Composite is a huge improvement over having the RF Modulator installed.

I wish I had some pictures of the Before. It is dramatic in this case. I was going to do the Chroma / Luma Bypass, those two pins on the lower right of the board. Without doing that, the video is comparable to my Commodore 64s. I feel it isn’t worth it at this point. I don’t want to bend out the VIC’s Chroma and Luma pins from the socket and solder wires to them. The improvement as it is was totally worth it. The two trimmer potentiometers are left set on the 180 and 75 ohm settings, I didn’t see a reason to adjust either at this point. I figure your probably safe to put in the standard resistors for those unless you want to go all out and tweak it to perfection. The same wit the Chroma / Luma bypass. You can still see Jailbars on the display, they are far better and overall the image is much sharper and cleaner.

I have recently build one of these up and installed it in a C64 Shortboard. For that one I did populate the Hard Reset section, but I didn’t put in a button or wire it in at this time. I used the regular resistors instead of the trimpots. I modified the Audio Jack to sit lower on the pcb, the jack I used is nearly identical to the one shown here. That helped the board sit more level in the C64 than on the C128 here. There are multiple pads for the Audio Jack, I was thinking maybe it is compatible with a slimmer jack type, but I didn’t want to risk it. I do have a slimmer jack that looks like it may have fit. The slimmer jack doesn’t seem as well built though, so I used the style I had used previously. You can lookup the more recent post showing that board. It is the same though, except sitting a bit more level due to the slightly lower mounted audio jack.

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 http://www.adafruit.com 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.

https://www.thingiverse.com/thing:3127040

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 than 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 than mine. 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.

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 it is 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, I tend to label it as “Option B+” or “Option B + SRQ”. There are people making pi1541 hats that include the SRQ lines, but I have seen no official diagrams posts, they are just doing it the way I am not that I am the first to do it. The SRQ I believe is needed for the 1581 Commodore 128 high speed transfers. 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, as I could have used it to replace 3 of the buttons (Rotary Encoders have rotate left, rotate right, and have a button that you can press them in).

https://cbm-pi1541.firebaseapp.com/

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: https://www.freepascal.org/~daniel/c64pla/

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 header strips. 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 also uses. The PLA in my other Commodore 64 is also socketed, but it has a the factory single wipe socket. Installing the round Machined Pin Headers into that may damage the socket which wasn’t a great quality when it was new 40 years ago. 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 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 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 some traces were shorted by the unclipped legs on it.. 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, 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.. 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.

Commodore 64 New Powersupply 2

This is just a little follow up to my C64 power supply post. Since I built that supply I have acquired a second Commodore 64 and I wanted to be able to hook up both. I decided to build a second supply based basically on the same design as the first. You can review the earlier post from the link below:

https://hobbytronics.home.blog/2019/02/11/commodore-64-new-powersupply/

I used the same case, same Meanwell 5Volt DC Supply, another salvaged IEC power port and switch. With a fuse. This time I didn’t have a spare transformer around so I had to order one. The new transformer is a Jameco 105524 9 Volt power supply. I wasn’t happy that it really didn’t arrive with useful info on what wire was which. I went back to Jameco’s listing for it to look up the wiring, which while the information was there, it was not posted in a clear manner. They have a scanned transformer diagram with 1-6 marked on it, then below it typed text saying what the various wires are by the “colors” of the wires. So go by the wire colors. It turned out that the 4 wires I needed were the same color as the other transformer (which only had 4 wires as it was a 110 to 9.5V only transformer). The new transformer was larger, I guess because of the 230V supply support? It still fit into the case I used previously. I also still mounted the transformer and Meanwell supplies to a piece of raw circuit board material. I did run a ground wire down to the one bolt on the transformer. Still it was grounded already due to the Meanwell case being grounded as well as the copper on the circuit board material.

The thing I still didn’t do that should have been done is grounding the metal screws and metal screen on the top of the case, if the Hot wire every pulled and contacted to the screen that would not be a good thing if it was then touched.

This time I did use crimp terminals on the wires going into the Meanwell screw terminals. The last time I didn’t have them around, and I think if they are tight they are a little safer that way. The other supply they are just bare stripped wire in the terminals which is ok, just make sure they are tight. Just Never Solder wires and put them into screw terminals, that may seem like a good idea, but it is dangerous because they will work loose over time as the solder is soft and tends to shift under the pressure.

I again did not include a “Computer Saver” or “C64 Saver” overvoltage protection circuit. The Meanwell does have overvoltage protection, but it won’t kick in until well after the damaging 5.4 Volts DC level has been hit..

The new supply. Sorry for the poor picture quality..

The screen is a little smaller this time around, it didn’t need that much of a vent. I thought it looked better that way than with the larger screen. I put the fuse on the bottom, as having it in the lid, I couldn’t put the nut on it before. The Hot/Line/Live wire goes first to the switch, then the back of the fuse holder from there, then through the fuse back over to the Meanwell supply terminal where the Transformer is also connected to it.

I wanted to do a power led… I forgot to. This thing is very tight, it would take a good bit for me to get the board loose so I could get back at the screw terminals.. I have to take the 5 screws out holding the board down, pull the fuse holder out the back, and feed in some of the output wire cord to lift that end of the board.. I am not wanting to risk pulling any of the rather short wires out of the crimp terminals, or making them loose and dangerous later on. I may go back and do it at some point. I would like them on both supplies. Basically some wires and a resistor to an LED off of the 5Volt output..

Here you see the new supply on the left with fuse holder on the bottom.

Another view of the back and top. The new one is a fraction darker plastic, be great a few shades darker though.

Here is the top front view of the supplies. The new one on the left again. I added the metal sticker I had ordered as well.

Above you see the finished supplies side by side. The metal stickers that I ordered from “marstickers” on Ebay turned out amazing. I believe they sell them on Etsy as well, as I found the listings there, the pricing is similar. That is also who I ordered the reproduction Commodore 64 Gold case badges form for my second C64. These are cut metal foil sticker, mirror finish. They came with a backer and clear top piece that holds them into position to get them placed properly.

A few little things, make sure the supply isn’t a bit under voltage at the connector. If the wire is too long (and possibly too thin), you get some voltage drop on the cable and that can be bad for the operation of the computer. I went with a wire around 4′, but some people go longer. So I get a slight bit over 5Volts (5.1V max) on both of my supplies at the power connector.

The wire I used is virtually the same diameter as the pins. It while is stranded wire, it is not very flexible and doesn’t have many strands in it. It is not perfect, flexing it too much will likely cause it to break. Still, it is real copper and is stranded, and a good diameter for the power lines.

The 5Volt 3Amp Meanwell supply should be 15Watts
The 9Volt 1.5Amp transformer should be 13.5Watts.

28.5Watts/110Volts = 0.259 Amps. Then the fuse should be rated at 125% of that. So 0.259*1.25=0.3238 Amps for the fuse at 110Volts

28.5Watts/220Volts = 0.1295 Amps. Then 0.1295 * 1.25 = 0.1619 Amps for the fuse at 220Volts

If you figure the Meanwell’s 77% efficiency that should move it to .366 Amps at 110Volts and .183Amps for 220Volts.

You should get the closest Amp fuse that is above the value calculated. Probably 400mA if you can find one at 120Volts or 200mA at 220Volts if that is your voltage there. If the rating is to close, then the inrush surge when plugging in could blow the fuse. You want to use normal (fast) acting fuses not “Slow Blow” fuses.

I am no professional at calculating fuse values. I believe that is correct though. The trick is you are figuring the Wattage usage of the supply at the top safe level of it (at the supplies efficiency level), so that you can then relate that power usage to the 110/220 AC, as that directly translates back to there.

The C64 won’t be drawing 28.5Watts out of the supply ever, unless something is wrong.

The factory supply (output) should be 16.5Watts 5Volt 1.5Amp (7.5Watts) plus 9Volts 1Amp (9Watts). So I expect the C64 won’t end up drawing more than that.

Factory supplies seemed to have 120mA or 200mA fuses on the AC line for 220Volt supplies. That seems to indicate they went with higher numbers, but they had 7805 regulators. With the 7805 to give out 1.5 Amps at 5 Volts actually used 1.5Amps at the input voltage, 9-14Volts probably. So they were using more nearing 21Watts (at 12Volt input) at full load. Well as the load increases the input voltage to the 7805 should in theory drop to close to 9Volts. Figuring that 120mA would be right for 21Watts.

The Meanwell has over voltage protection, I did not include a fuse on the 5Volt DC after it. If you did, you would want a 1.5Amp fuse probably there as the Commodore 64 should not pull that much safely anyways although it may blow before the protection on the Meanwell trips, although the Meanwell may still trip faster than the fuse will blow.

Power connector. You can see the wires aren’t tiny compared to the pins, 2 strands are also removed to get them to fit.

This is just what I did, I have not included any wiring diagrams or detailed parts list. It is a rather simple build really. The Meanwell gets the direct 110Volt AC to it, along with ground. The Transformer gets the same direct110Volt AC. Everything else is sending the right wire to the output on the Din power connector hta goes to the Commodore 64. This same setup could be used for a Commodore 128, swapping in the proper power connector, as the 9Volt AC transformer I used and and the 5Volt Meanwell supply I used can handle the additional current load. While this is a simple supply working with AC mains from the wall outlet isn’t a safe thing to do if you don’t know what you are doing. Like I mentioned above, the metal screen and the metal screws that hold it on SHOULD be wired to Ground for safety, if built into a metal case or having any external metal should be grounded, such as the screw heads. The enclosure’s metal corner screws are electrically isolated so they aren’t a problem in this exact case. I expect if I go back and add the Power LEDs that I will be grounding the metal screens in my case. I have been building supplies off and on for a couple decades and have a few years of electronics training having worked with open chassis and vacuum tube electronics back in school. Doing a supply like this is something you should really look at carefully if you go to make one of your own.

There is a simpler way than to work directly with the AC directly and wiring things up. You can get a good quality 5Volt DC AC Adapter, and if you look carefully you can find some 9 Volt “AC” adapters (often used for older security systems I think, but what for in them I don’t know, but you can still find them). Then you can take an extension cord (even a 2 wire one if both Adapters are 2 prong plugs, be sure it is heavy duty enough though), plug those two adapters into the extension cord and hide that inside an enclosure, cut the cords and wire in a cord with the Din power connector for the C64. Jan Beta had has done just that, it is likely a safer project. Retro Recipes has as well.

I have also added a power LED to the top of this second unit.

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.

Console5.com 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: https://console5.com/store/commodore-64-power-saver-circuit-kit.html

Ray Carlsen’s pages: http://personalpages.tds.net/~rcarlsen/cbm/c64/SAVER/

Toner Transfer Post: http://www.robotroom.com/Toner-Transfer-Etching-2.html

Etching Post: https://www.instructables.com/id/Is-the-best-PCB-etchant-in-every-kitchen-/

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.

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.

https://github.com/SukkoPera/OpenC64Saver

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 Console5.com 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.

Commodore 64 Breadbin #2 Referb : 326298 Part 3 Recap & abit

I had mentioned the video fix for this board in Part 1, but I don’t believe I went over it beyond mentioning. So here it is, Ray Carlsen recommended resistor change for improved Video. These boards shipped with an incorrect resistor installed in the VIC II area, that reduces the level of the Composite Video output.

https://portcommodore.com/rcarlsen/cbm/c64/SCHEMATICS/326298/early%20board%20weak%20video.txt

The resistor is R10 next to the VIC chip. His recommended fix is to add another resistor across the factory installed one. By doing this with the right value of resistor, you can get it set to the proper value. It is easier and safer to pull the resistor and replace it. Anytime you desolder a component you risk damage to the rather delicate circuit board traces. It can be done to look very neat as well.

You should be able to see the “stacked’ blue resistor overtop of the factory installed R10. This combination reduces the value to what it should have been. That did noticeably improve the video output. The factory resistor is 300 Ohms, the resistor that should be there is 120 Ohms. So obviously the signal is reduced. When putting a 220 Ohm resistor across the 300 that takes the value of the two resistors together to to give you around 127 Ohms, so that should be plenty close to the 120 that should be there.

So I managed to replace all of the electrolytic capacitors this C64. The Modulator was quite a pain this time around. Also due to that, I let my desoldering iron sit on idle hot for too long. The tip on it started to break down, so I will have to get a replacement. It worked well enough to finish the job though.

I know some people say replace the capacitors, some people say don’t mess with them if it is working correctly.

I say I hate desoldering the RF Modulator, but as far as something causing something I may see, if the modulator caps are going bad that will affect the video output. The RF Modulator is tied in and affects the Composite output as well, as it usually passes through the modulator. It turns out on this revision though the Composite does not go through the modulator, so it seems on this revision you can possibly just remove the modulator. I haven’t verified that though, and don’t intend to try it at this point.

Above I have prepped to work on the capacitors. They are there, as well as my iron and desoldering iron, and solder collection can that I expel the solder into from the desoldering iron.

As I said the modulator was a pain. They had not “turned” the ears on the modulator to hold it in, they had bent over the small pins. I had to work the modulator loose by getting what I could off and putting pressure on the tab I had loose and hold it down while it cooled, then work my way around. I also ended up pulling the 3 square pins up out through the modulator top. That was my best bet to not lift traces. By heating them with my soldering iron from the top side inside the modulator, until it could put pulled up with my pliers that I was holding the pin with. Once they were out of the way, it was one of those pieces they bent over that was stuck in the end making it so I could remove it. I did loose some of the bottom pads, or do a good bit of damage to them where they can is soldered in with the tabs. In the end it doesn’t look too bad, the one that fell off I put back in place and reapplied solder. The one square pin lost the narrow pad from the bottom, but not the through hole thankfully. It was the audio pin and that is why I decided to just heat and remove them pulling them up out. It was a good idea. They are a tight fit, so once I had them out, I ended up using a small file to file off the old solder so they would fit again. You don’t want them loose, because they are double soldered, you risk the solder loosing contact then.

After getting the modulator off, I replaced the capacitors in it, then went and replaced the remaining ones on the mainboard before reinstalling it.

I cleaned the tabs and such on the modulator body and the holes in the board to make sure it would fit back in easily. After that I reinstalled the cleaned up pins into the modulator. In the picture the center one had some solder on it again as I had started to reinstall it but pulled it back off.

I actually pulled it off, so I could check where the traces went under it, for those three pins. I wanted to be able to make sure they were making good contact before finalizing the work. So I reinstalled it, but I did not solder any of the tabs back tight before testing.

She still worked after the replacements. I haven’t tested the Keyboard or Sound though yet. Yes I was wearing an ESD Wrist Strap and working on my grounded ESD Mat.

After it tested good, I then twisted the tabs on the modulator and soldered all of that back on. I did a bit of cleanup of the flux and reinstalled it into the bottom case. Now I need to do that keyboard work so I can put this all back together and use it again.

The new tips came. I am going to be more careful about leaving it idle when it is not in use.

Here is my desoldering tip. I have seen this happen with Copper based tips, I guess this is Brass looking? If the hot solder is left on them it starts to dissolve the metal of the tip into the solder. It is replaceable, and I like the iron so ordered in a replacement for it. Once they start doing that they keep breaking down. Other types of tips will just burn the plating off and then will quit accepting solder and not transfer the heat properly. I will not leave it idle like that while it is on again. It was while I was working with the modulator, which may have taken a hour. I was taking care to not wreck it, so it took awhile.

Beyond the modulator it was an easy recap. Most of the capacitors I pulled tested pretty reasonable but not all.

Three of the 10uF capacitors tested with almost no capacitance. Otherwise they were a little inconsistent and all of them measured above their stated values. The new ones are closer to their rated values. With those three odd ones, I feel it was worth it.

Well on to revisit the keyboard. I really don’t want to take it apart again, but the * key is kind of important. So I will get that in the next and likely last post on this refurbishment.