From: ddkilzer@iastate.edu (David D Kilzer)
Subject: Re: Apple IIc acting STRANGE!
Organization: Iowa State University, Ames, IA
Date: Sun, 4 Oct 1992 15:04:19 GMT

In article <91561@netnews.upenn.edu> kupiec@hp800.lasalle.edu (Bob Kupiec) writes:
>There is a strange problem that has been occuring on my IIc for a
>while now.  Here are the symptoms:  Sometimes the character generator in
>the machine will go nuts distorting characters, or "snow" will appear on
>the screen.  Other times the screen will totally flip out like someone has
>messed with the monitor's horizontal hold.  A "hiss" can be heard when this
>happens.
>
>I know that the problem *IS* with the COMPUTER!  The monitor is FINE
>and the video co-ax is FINE.  The problem is WITHIN the computer.  I
>removed all the socketed chips (they seemed to have some kind of corrosion
>on the pins which I partly removed) and re-seated them.  It seemed to help
>for a while but the symptoms still show up.
>
>The motherboard is a Unidisk 3.5" model and not a "old" type.  Is there
>anything I should be looking at in particular?  Do IIc's have this problem
>or am I an isolated case?  Any hints on where to start looking would be
>helpful.  I'm running out of ideas.
>
>Please followup to the address below because I don't follow this newsgroup.
>Thanks for your help!


Have you tried a self-test?  The older-ROM //c's didn't have the routine
built-in, but in the newer ones (including your's) have it.  Try
pressing control--open-apple--closed-apple--reset.  The computer should
go through a series of graphic "kaliescope" screens, then give you a
message about the system.  If "System ok" appears, every thing "should"
be okay, but still may not be.  If another message appears, I'd suggest
posting it to this newsgroup and asking what it means.

I had a similar problem recently.  Whenever I turned on my //c, grave
accents would appear in strange places on the screen and flicker.  The
computer would boot up, but any programs that required more than 64K
would crash (the 40-column screen looked fine, but the 80 column screen
had these grave accents on it).  I came to find the problem was that one
of the RAM chips in the AUX bank (the extra 64K that makes the base //c
have 128K) went bad.  Once I replaced it, everything works fine now.

One important note:  If you have a Zip chip (or RocketChip) installed
or a memory expansion board, you might want to remove them before doing
the self-test.  When I first did a self test with my 1 Meg. Z-RAM Ultra
II and 8 MHz Zip Chip installed, a "System ok" was returned.  However,
once I removed both the Zip Chip and the memory expansion board and did
another self-test, I got the following message: "RAM*   0 1 0 0 0 0 0 0".
This told me that the second RAM chip from the top of the logic board
(top being the side with all the ports) in the AUX bank (indicated by
the asterisk) was bad.  I ordered a replacement chip and new socket
(actually, two of each) from Alltech Electronics (see their ad in
inCider/A+; or write me for address & phone number).

If you get this error message, I can put you in contact with the guy who
helped me thru fixing my //c.  He wrote me a ten or so mail messages
before I attempted to repair my computer.  If you don't get this error
message (but I suspect you will :), you can still post to the newsgroup
and ask what it means.  You may also be able to buy a replacement chip
from Alltech if it's another type of chip that went bad.

Good luck!  *crossing fingers*

Dave

[P.S.--Yes, I sent the same message to the original poster.]
Newsgroups: comp.sys.apple2