From: Ian West (imw_at_drykid.plus.com)
Date: 2004-01-19 23:51:38
RE: Dead PET
----- Original Message -----
From: Baltissen, GJPAA (Ruud)
To: 'cbm-hackers@cling.gu.se'
Sent: Monday, January 19, 2004 10:54 AM
Subject: RE: Dead PET
>Hallo Ian,
>> I've checked the power supply output, and all the outputs from it
>> seem to be around 15-16V AC, ....
>More important is to check if you have 5 Volt at the IC's.
Hmm I checked the main ICs (6502 6522 etc.), and all of the pins were
between 0v and 5v, which seems right. However, I've since noticed something
else which I think may be related to things - there's a ceramic capacitor
(C68) in the LM555 timer circuit that seems to be cracked open. Since the
LM555 seems to drive all sorts of things according to the schematic, then it
looks like I need to replace this before I can begin to look for any other
problems.
I also managed to break a pin off one of the ROMs through one of my clumsy
attempts to remove it and clean it :( Although from the corroded state it
was in it was probably already dead (or so I hope, that way I don't feel so
bad about breaking it.) Hopefully it was an add-in ROM of some kind, and
the machine can work without it.
>> but the only ones I could find that seemed close were for a
>> 2001-N, and I'm not sure how similar a 3000 series is -
>http://www.funet.fi/pub/cbm/schematics/computers/pet/re/index.html
Thaks for that, though it only seems to have the 3000 series main board
schematic, and not the video board one. However, now it looks like there's
a problem on the main board, I'm not too concerned about the video board for
the moment.
Ian
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