Re: Stange display problem Apple ][c

[Rubywand <rubywand@swbell.net>]

Alexander Melchers writes ...
> 
> I recently got a memory expasion-capable Apple ][c and I have a strange
> problem with the display...
> 1) Graphics display fine, but when in text mode, very often one line of
> text starts at one row and finishes on the next...
> 2) Often, in text mode, I get random characters at random places on
> screen...
> 
> When I run a self-test, it reports back that the system is OK...
 ....

     The problem may be an intermittant memory glitch. One check is to run
the self-test 2-3 times.

     Possibly, a more likely explanation is a faulty or poorly socketed IC in
the display circuitry. If memory, soft switches, etc. are okay, the self-test
would report no problem. Meanwhile, a shift register IC, multiplexer IC, MMU,
or other chip could be glitching when text is sent to your video output. 
     Try cleaning away dust and removing any goop (from coffee, etc.
spills).  Then, scootch up and resocketing every IC in a socket. These steps
may cure a short or bad pin connection and eliminate your display problem.  



Rubywand