Need help fixing a C128 DCR

From: Laze Ristoski <cybernator64_at_gmail.com>
Date: Thu, 24 Jun 2010 14:46:30 +0200
Message-ID: <AANLkTikQ2DjnmAbzajmFhJy8FMNgLq89CmWzyvAUM2bd@mail.gmail.com>
Hello everyone,

I asked this question elsewhere and so far I was told to replace the RAM.
But I'd like some more hints so as to avoid raping the PCB too much. :)

The C128 screen shows up (Basic V7, etc) but with randomly colored chars (not
flashing though), and no cursor shows up. The floppy drive seems to finish its
start-up sequence no problem. I've tried using a C64 cartridge, holding down
Commodore key during start-up and switching to 80-column display, but
the results
are always the same (ie. always getting the 40-column C128 mode). So
far I replaced
the MMU, PLA and VIC, but without any luck. None of the chips are
getting abnormally
hot. The VDC seems to produce no signal, or at least that's what my TV-set says
(I use the monochrome output). I'm not sure if a faulty VDC can cause
these symptoms.

Any ideas what might be failing?

--
Laze

       Message was sent through the cbm-hackers mailing list
Received on 2010-06-24 13:00:04

Archive generated by hypermail 2.2.0.