bug2k17

Thanks for the help. I have checked visually and cannot see any broken or burnt tracks. The reset button appears to work correctly, I'll check the signal to the cpu later just to make sure. I have put a scope on the IC pins suggested in the SAMS diagnostic pdf and they seem correct.

Thanks Mark, yes I have tried on the Facebook page, but nothing new has come from that. I will join the list and see if any further information is available there. I have seen that Dave Jones at EEVBlog has just taken what looks to be a PAL Coco1 apart in a recent video, but no new information on it. I see that the chip on his board has a different number to the one above I am looking for. I might drop him a msg and see if he knows anything more on it.

The model is a 26-3003. This is a UK PAL version with 32k (uses 8 64k x 1bit memory chips) with Extended Basic. Thanks.

I'm trying to fix a fault on my Color Computer, I broke this over 30 years ago while playing with a diy cartridge slot board. I put it to one side and never got round to fixing it. It now powers up and show random characters on screen, but no prompt. I'm just trying to work out the power line requirements for the major chips. Are schematics available for this version of the board? I have now socketed all the ICs on the board. As I have a Dragon 32, which uses mostly the same chips, I have swapped out most of the ICs in to the Dragon and seem to work fine, such as the cpu, 74ls783, 6821, 6822, 6847, 74ls138, 74ls273, 74ls244. I also have 2 sets of working ram chips which do not seem to make any difference. I have checked the power and ground to all ICs and they are fine, with the exception of one chip for which I cannot find the datasheet, I have attached a picture if anyone can help on where to look. Thanks.