Re: Monitor problem

[Rubywand <rubywand@swbell.net>]

Al Boisvert writes ...
> 
> I have an Apple IIGS RGB monitor which is acting up.  The screen fades away
> to
> total "black"; and returns at times for short periods (longer at times) when
> I rap it on the sides with my hands.

     Reminds me of a Dr. Who episode where he bonks a computer console to get
an ancient space ship going and comments: "I love Earth technology!"


> Might someone know the cause?
> 
> I do have a spare which I'm using now, without any such problems.
 ....

     This sounds like the famous fractured solder joint problem which seems to
plague so many GS monitors (including ours, for a while).  It turns out that
the eyelet holes in the main circuit board are too big for the pins coming from
the High Voltage Module-- the black thing with the fat lead going to the CRT.

     So, the solder connections for the HV Module are little lakes of solder
with a pin in the middle. Over time some of these 'lakes' fracture around the
pin resulting in intermittant connections. (You can look right at some of these
breaks and the fracture is so fine you'll miss it without a magnifying glass.)

     The cure is to resolder all of the connections to the HV Module using high
quality solder. The connections are in a rough circle and easy to spot from the
bottom of the board. (The repair, how to open the case, and some safety
precautions-- wear goggles, don't knock the CRT neck, avoid touching two
conductive surfaces at once, ...-- are discussed at
http://home.swbell.net/rubywand/Csa2MONITOR.html .)

     There are a few other possibilities-- like a bad connection where the HV
anode lead clips into the CRT or, even, a dirty control (you might try turning
some controls back and forth next time you get a black screen).  Still, if you
open the case and inspect the HV Module connections carefully, the odds are
pretty good you'll spot a few where the pin is encircled by a nearly invisible
fracture.



Rubywand