C128 repair advice...

From: Bo Zimmerman (bo_at_zimmers.net)
Date: 2002-02-24 19:37:49

Hello all,

I've been tinkering with Georges prototype C128 of late.  It's a REV0
motherboard without an FCC sticker, but with a serial number of 145, and
REV2 and 3 EPROM ROMs.  I replaced the three broken keys from the popular
G.P. collection photos, and made a stab at getting it to boot up.  That,
however, has proven difficult.

The basic symptom is a black composite start-up screen.  Using a working
C128, I managed to confirm that all the socketed chips from the prototype
machine are OK.  This includes the ROMs, both video chips,  and the 8722
(MMU?).  The MMU is actually the only chip I noticed as being an unusually
old revision, being a REV1.

Anyways, I'm a bit at a loss.  I'm not very excited about the prospect of
socketing memory and processor chips, just like I would ANY old C128, in
order to fix it.  The only other clue I noticed is a particularly hot
running Z-80, compared with the Z-80 in the working C128 I'm using for

Any advice is appreciated, though I'm still wondering if doing anything at
all is a good idea, since any changes would put this motherboard in the
hands of a solderer who is merely fair at best. :)

- Bo

       Message was sent through the cbm-hackers mailing list

Archive generated by hypermail 2.1.1.