RetroB1977 Posted June 28, 2022 Share Posted June 28, 2022 I bought a Tandy Color Computer 1 at an antique store the other day. It boots to extended BASIC just fine, but every so often it will crash to a screen will a bunch of random characters. Is this a RAM problem? Or could it be some interference on the power supply or something? Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted June 28, 2022 Author Share Posted June 28, 2022 (edited) (Deleted) Edited June 28, 2022 by RetroB1977 1 Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted June 28, 2022 Author Share Posted June 28, 2022 Nevermind, the problem must have been interference. I plugged it in to another room in my house and it works just fine. 1 Quote Link to comment Share on other sites More sharing options...
MrDave Posted June 29, 2022 Share Posted June 29, 2022 You might want to clean and reseat any ic's probably moving it fixed it.. not sure you could have enough interference to disrupt a coco.. Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted June 29, 2022 Author Share Posted June 29, 2022 (edited) 7 hours ago, MrDave said: You might want to clean and reseat any ic's probably moving it fixed it.. not sure you could have enough interference to disrupt a coco.. Well I do have these little powerline ethernet things, but the problem decided to happen again. Edited June 29, 2022 by RetroB1977 Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted June 29, 2022 Author Share Posted June 29, 2022 This thing had a 64k mod done to it. Quote Link to comment Share on other sites More sharing options...
MrDave Posted June 29, 2022 Share Posted June 29, 2022 Is your capacitor c7 in good shape ? Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted June 30, 2022 Author Share Posted June 30, 2022 12 hours ago, MrDave said: Is your capacitor c7 in good shape ? I don't have any sort of LCR meter to measure it, but it looks ok. Quote Link to comment Share on other sites More sharing options...
Bruce Tomlin Posted June 30, 2022 Share Posted June 30, 2022 Did you reseat the ram chips? After a couple of decades they will get oxidation in there and need just a bit of movement to crack the oxidation. Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted June 30, 2022 Author Share Posted June 30, 2022 1 hour ago, Bruce Tomlin said: Did you reseat the ram chips? After a couple of decades they will get oxidation in there and need just a bit of movement to crack the oxidation. I just did, still happens. ? Quote Link to comment Share on other sites More sharing options...
JamesD Posted July 4, 2022 Share Posted July 4, 2022 Might have a bad SAM chip 1 Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted July 4, 2022 Author Share Posted July 4, 2022 20 hours ago, JamesD said: Might have a bad SAM chip I was starting to suspect that. I wish I had some sort of way to test it. ? Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted July 5, 2022 Author Share Posted July 5, 2022 I think the problem is the RAM. I swapped two of the RAM chips around and it wouldn't boot up (I made sure they were making good contact), but swapping them back it will. Quote Link to comment Share on other sites More sharing options...
MrDave Posted July 5, 2022 Share Posted July 5, 2022 I recently bought a arduino based ram tester.. I had made one once.,but took it apart.. 2 Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted July 5, 2022 Author Share Posted July 5, 2022 Not to jinx myself, but I think it's fixed. I was able to run a 64k RAM Tester program, which said I have 64k. I don't know if it tests the chips fully though. Is there any program I could load in from cassette to fully test the RAM? Quote Link to comment Share on other sites More sharing options...
MrDave Posted July 5, 2022 Share Posted July 5, 2022 Running this will put everything in ram..even the basic roms Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted July 5, 2022 Author Share Posted July 5, 2022 (edited) 40 minutes ago, MrDave said: Running this will put everything in ram..even the basic roms Ok, I'll try it. Edit: It started crashing again. The SAM has to be bad, right? Edited July 5, 2022 by RetroB1977 Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted September 6, 2022 Author Share Posted September 6, 2022 When the machine crashes the color sometimes goes monochrome and the video goes crazy. Is it possible that that is a SAM problem? Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted November 8, 2022 Author Share Posted November 8, 2022 Update: I swapped the RAM and it still crashes. 😕 Quote Link to comment Share on other sites More sharing options...
MrDave Posted November 9, 2022 Share Posted November 9, 2022 Your caps are good ? Quote Link to comment Share on other sites More sharing options...
MrDave Posted November 9, 2022 Share Posted November 9, 2022 Your caps are good ? Hmm i already asked that... lol Change your 1500 uf cap for a new one ! Quote Link to comment Share on other sites More sharing options...
MrDave Posted November 13, 2022 Share Posted November 13, 2022 Compare this cap to the one on ypur board which is bulged out.. Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted November 21, 2022 Author Share Posted November 21, 2022 On 11/13/2022 at 1:04 PM, MrDave said: Compare this cap to the one on ypur board which is bulged out.. Yeah mine does look bulged, I'll replace it. Quote Link to comment Share on other sites More sharing options...
RetroB1977 Posted November 22, 2022 Author Share Posted November 22, 2022 By the way, the RAM chips I swapped are 41256s. All the pins match except pin 1 is NC on a 4164 and A8 on a 41256. Is it safe to leave these chips in the machine? Quote Link to comment Share on other sites More sharing options...
MrDave Posted November 23, 2022 Share Posted November 23, 2022 I would say its not a good ram to use Quote Link to comment Share on other sites More sharing options...
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