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VIC-20 Randomly Crashing?

C

Capt. 2110

Experienced Member
Joined
May 23, 2015
Messages
362
Location
Texas
I have a VIC-20CR that I repaired a while back. It's been having some new issues, and I'm trying to figure out what's wrong with it. If it's been running for more than 30 minutes, it begins to crash in different ways. It has a new power supply, I've recapped the board, and I've resocketed all socketed chips. Sometimes if I'm running a program, the program will suddenly stop and return to a cleared screen with a READY prompt at the top. Relaunching the program sometimes works, but other times it appears to have cleared the program. If I try reloading the program from my 1541, it gives errors like "ERROR IN 42033 ?FORMULA TOO COMPLEX", even in short 20 line programs. Other times, when running the program I get "ILLEGAL QUANTITY" errors and general "ERROR IN LINE X" errors, even if the last run went perfectly. At one point I ran a counter program to test how long it took to crash while running a program, and it ran fine for 447 seconds (about 7.5 minutes) before returning "00044" followed by a petscii L, a question mark, and a triangle, followed by "ERROR IN LINE 0". Rerunning the program showed the count was still OK, and it ran for a while longer before crashing again. Sometimes it will crash while writing a program too, by just hanging. Does anybody know how I can diagnose my VIC-20? The RAM isn't socketed, but all ROMs, the 6522s, the VIC chip, and the 6502 are. Thank you!!
 
I had a similar problem, and it was a RAM chip that had some problem when it warmed.

Can you try to keep your RAM chips cool, one at a time? you could use an heat sink with some heat sink white grease (i.e. I use to take the bios/vga heat sinks from bad, old PC motherboard, cutting them in stripes).
It could gives you some clues, in case a RAM chip is the culprit...
 
Cool, I'll try that out and see which one it is. Thanks! Just curious, which RAM chip on your machine was it?
 
gosh, I have some VIC and I fixed few of them, I can't remember if it was the big RAM IC model (most probably) or an earlier one, with more, small RAM chips.
 
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