Re: C128D troubleshooting?
                                       
   From: Raymond Carlsen <rrcc@u.washington.edu>
   Reply to: Raymond Carlsen
   Date: Wed, 10 Feb 1999 08:07:05 -0800
   Organization: University of Washington
   References:
          <36c0515b.0@news.infinetgroup.com>
> Just got my 128D (metal case, no handle) back from a trip in the mail.
> Found the drive piece that pops the disk out of the drive (L shaped piece of
> metal) UNDER the power supply, missing the spring. Robbed another 1571 to
> hook it back up, but have other problems:
> 1 - Many read errors on disks, I can re-align the drive, have done other
> standalone types, but not an internal 1571 - Anyone have any tips?

I just wondered if you turned the computer on with metal parts floating
around in there. <shudder> If so, all bets are off. Transporting a 1571 is
especially hard on it. Alignment problems are rare. They just don't go out
of alignment that easily. I would go through the mechanics of the drive,
pay special attention to the position of the top head. Check out the
article regarding repairs of the 1571. I'll point you to a few sites with
those articles. If you can't find what you need, email me and I'll try to
help. Find ALL the missing parts, by the way. You may have to gut the
computer to do that (metal spring under the motherboard?).

> 2 - I'm stumped on this one - Intermittently (at least last night it
> happened 4 times), after a reboot, there was no video, the computer didn't
> go thru it's usual noisy init of the drive, or attempt to autoboot.  Typing
> commands on the keyboard did nothing. Any suggestions on things to try for #2
?

I would begin with reseating all the socketed chips. "Metal case" means
128DCR, so check also the power supply connector pins on the motherboard
for corrosion and clean as necessary. Make sure you get the connector back
on the right way. Mark pin 1 with a dab of ink before you remove it. If the
computer still fails to reboot, check it in both modes when warmed up and
again when cold. A failing chip can be heat sensitive. If it -always- fails
like that when warmed up, heat must be a factor. Three computers in one box
makes for a LOT of chips to check. Some are used in common and some for
each function (ie C64 mode only). Your only hope is to narrow it down to a
specific area and go from there. You must be very watchful for -exact-
symptoms when it starts acting up... what works and what doesn't. Consider
a fan. They do help.

For more information, see the repair articles on the following sites:
http://www.prismnet.com/~bo/commie/repair.html
http://www.funet.fi/pub/cbm/
http://sunsite.unc.edu/pub/micro/commodore/documents/repair/index.html

Repair parts:
http://www.paxtron.com
http://pw1.netcom.com/~jspusa/jspzone1.html

Ray Carlsen CET
CARLSEN ELECTRONICS... a leader in trailing-edge technology.