20 May
2012
20 May
'12
1:30 p.m.
Success! I thought I had done the whole reseating of the chips
in the socket thing, but messing more with the VRAMs as per your
suggestion, seems to have soveld the problem. I tried swapping them and
that just made things worse, so I swapped them back and it worked great.
Looks like some oxidation in the sockets/pics. So I removed the PETvet
and replaced the 6502 and for now, it is running well. Now to test the
rest of the machine. Thanks for the help.
I am not really a Commodore person, but of the few PETs I've repaired
I've had no end of problems with IC sockets. If oyu intend to keep.ru
nthe machine, I'd remomened removing all the IC sockets and repalicng
them with turned-pin (machined pin) ones. It may cost a few
pounds/dollars, but you'll find a lot of nasty faults go away..
Oh, and the power connector (the 0.156" Molex thing) is another cause of
problems. It's a bit under-rated for the current it has to carry, it
tends ot run hot, oxidise, run hotter, and so on. It's also a cause of
difficult-to-find faults (unless you suspect it).
-tony