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Path: severus.mbfys.kun.nl!rhialto
From: rhialto@mbfys.kun.nl (Olaf Seibert)
Newsgroups: comp.sys.cbm
Subject: Re: Dead PET
Date: 4 Dec 1995 13:18:35 GMT
Organization: University of Nijmegen, The Netherlands
Distribution: world
Message-ID: <49usfb$c1m@wn1.sci.kun.nl>
References: <49k41v$3dnb@unixfe.rl.ac.uk>
NNTP-Posting-Host: severus.mbfys.kun.nl
In <49k41v$3dnb@unixfe.rl.ac.uk> Mark Smith <mark@te.rl.ac.uk> writes:
>Help!
>I have a dead PET. The model number is somehting like X032, I can't
>remember
>off hand - I've only just got it. It's the one in the rounded case.
8032-SK, most probably. Does it have a detached keyboard?
>When I switch it on, the speaker warbles at me a bit like when you hit a
>space invader on the original arcade machine!
>Then, it sits there doing nothing. The monitor doesn't come on - inside,
>the
>heater on the CRT light up, but there is no high voltage supply. I've
>checked
>all the trannys and diodes plus most R's and C's and I now reckon the
>monitor
>is ok. I've checked the lum, horizontal and vertical sync inputs to the
>monitor
>from the PET main board but they see to be flat - no spikes on the screen
>of
>my oscilloscope at all.
My first guess would be the CRT Controller, a 6845 (or 6545).
It is a 40 pins device somewhere vaguely near the middle of the
motherboard. In my machine it is completely unmarked though.
Motorola has a nice www site where you can chek if they are still
available. Try looking at http://motserv.indirect.com/.
>While I'm on about it, what is the number on the CRT controller and what
>are
>the numbers of the other chips and their functions?
>
>If you can help me with all that, you must be some sort of superhuman but
>I
>think I could do with one of them to help fix this thing!
I'll send you my PetIO.doc file (posted here about 1-2 weeks ago)
under separate cover.
>Cheers,
> Mark Smith, e-mail mark@te.rl.ac.uk
-Olaf.
--
Copyright 1995 Olaf 'Rhialto' Seibert. All Rights Reserved.
X/ You are not allowed to read this using any kind of Micro$oft product.