Re: Apple //c , hardware(?) problem

[ddkilzer@iastate.edu (David D Kilzer)]

RKE <gardnern@ats4.colorado.edu> writes:

>I have a //c that has been on a shelf for awhile and I wanted to get get
>it back up and running.  Whenever I turn the computer on, I encounter the
>following: 
>
>1) With no disk in the drive - The computer gives it's "Apple //c" and
>"Check Disk Drive." messages.  It also put's a "`" (backwards accent) on
>the middle of the screen.  If I press Control-Reset to get into AppleSoft,
>the computer will always place an accent in the middle of the display. 
>All of Basic's commands seem to work fine. 
>
>2) With a ProDOS disk in the drive - No matter what, with or sans the
>PRODOS system file, the computer shows "UNABLE TO LOAD PRODOS".  I have
>the same accent problem as described above. 
>
>3) With a DOS 3.3 disk - The computer seems to boot fine and it even tries
>to read the disk but after a moment, it drops into the system monitor at
>$9D86.  Once again, I still have that stupid accent problem. 
>
>4) When I try the self-test - There is a "!" (on the graphics screen) for
>a moment.  Periodically, The external drive comes active and the speaker
>clicks, sometimes independent of the drive.  The testing cycle never ends. 
>
>I have a copy of Apple Diagnostics 2.0 but because of the ProDOS problem,
>I can't run the program.  There doesn't seem to be anyone who will service
>the computer either (I find it ironic that I can still get my old IBM
>PCjr. serviced but once someone hears "Apple 2" forget it - and I don't
>even like IBM's).  If there are any hardware gurus lurking about that
>could offer some advice, I would be thankful. 

Sounds like a bad RAM chip.  If you have any replacements, I would try
replacing them one at a time and restarting.  Since you don't have a
//c with a self-check, you can't find out which one is bad (or how
many).  :^(

See the FAQ for information on who to contact to get replacement chips.
I believe All-Tech Electronics sells them, among others.

Dave
-- 
David D. Kilzer              \        Emergency Holographic Doctor:
ddkilzer@iastate.edu         /   ``Don't worry, I'm not going to kiss you.
Computer Engineer 4          \      I'm only adjusting the restraint.''
Iowa State University, Ames  /         _Star_Trek_Voyager:__Phage_