Re: Low Res on IIGS Monitor-- arcing

[Rubywand <rubywand@swbell.net>]

Benjamin O Zotto writes ...
> 
 ....
> 
> My RGB monitor occasionally flickers and the color values alter in a tiny
> way for a few seconds. This happens after it's been turned on for awhile.
> Is this the symptom of arcing?

     Yes; but, there are other possible causes. Heating may affect any
marginal connection.

     One or more bad solder connections on the HV module (where it connects to
the main circuit board) may be affected by heat. Or, heating may affect a
'dirty' control. For breaks like these, tapping on the case will often
reproduce the flicker.
 
     If the problem is arcing, you may (listening close to the case) be able
to hear a faint sizzle or pop sound which coincides with a flicker.


> Once it's started happening is the monitor
> a lost cause or can giving it a clean (as Rubywand describes) stop future
> problems of this kind?
> 
 ....

     The arcing I'm talking about is from a portion of the black HV module to
a nearby metal brace. (It is not too difficult to see the small violet arc hop
across the gap with the case removed.) 

     Opening up and cleaning the case every few years is a good way to help
prevent a number of problems, including arcing. Once you have arcing, it
probably will not cure it.

     A fix which worked on our monitor was to first bend the metal brace
slightly to increase the distance from the HV module. Then, use an alcohol
swab to clean parts of the brace and HV module where they are closest.
Finally, apply High-Voltage insulating dope to both surfaces. (The dope is a
liquid plastic which may even be called "anti-arcing dope".)

     Opening up and working on a monitor involves some hazard-- electrical
shock, getting tossed off a stool, breaking the CRT and being sprayed with
glass, ... .  There is some info on safety, removing the case, and doing
repairs in the Monitor FAQs:

http://home.swbell.net/rubywand/Csa2MONITOR.html
ftp://ground.ecn.uiowa.edu/apple2/Faqs/
http://206.14.25.120/~cturley/a2faqs/



Rubywand