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. aroub 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.

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