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Hi Everyone, I recently picked up an VIC-20 to repair, and fixed all the minor issues on it. The big issue for it was that the 6560 was bad (the giveaway was no clock out of the VIC-I, but a good clock in to the VIC-I; I verified by swapping in a known good VIC-I from my personal VIC-20). I...

Hello All, I'm in the middle of an extensive repair of a PET 2001. Most all of it is fixed up, but I wanted a double-check on the last item to fix. The video is sometimes stable, especially when first powered on. However, I am getting frequent vertical video shake, and on occasion the video...

Hi Everyone, I am repairing an NTSC C64 breadbin (205407) for a friend and I have encountered a very strange situation. When I first got it, it displayed a black screen. Checking the PLA in a working C64 of mine showed it was bad. Swapping it with a working PLA did not get me a picture on the...

Hello Folks, I recently picked up a new VIC-20 that needs some work. When the VIC is powered on, my 1702 has a black screen. This is a 324003 rev board, so its an early model with the 2114 RAM. I verified I have 5v and a good clock. I also reseated all socketed chips with some deoxit. I...

Hello Everyone, I recently came into a Plus/4 that I have nearly working. I have a few days where I cannot troubleshoot more, so I figured I would post to the board, and see if you all have a better idea than mine for what to test next. The Plus/4 boots to BASIC v3.5 just fine. When I type in...

Hello All! I am so glad that everyone here takes such an interest in vintage computers! I recently came into a PET 2001 (black bezel) with the chicklet keyboard and 6550s/6540s. It has 6540-019 in it, so I guess that's the revision before the RAM/ROM was changed out from the 6550s/6540s. When...