Re: My RGB went green!

[kheidens@actrix.gen.nz (Kris Heidenstrom)]

In article <36a8eu$2kr@news.u.washington.edu>,
Ron Louie <ronlouie@u.washington.edu> wrote:
> My Apple II RGB went totally green on me!  Just the night before, 
> [...]
> brightness knob did nothing, the other knobs, very little.  It glowed 
> green even with the computer cable detached.

This symptom is often caused by a damaged video output transistor,
usually damaged by flashover in the picture tube.  The video output
stages look like three identical-looking circuits (for red, green
and blue), with one or two medium-sized transistors per channel.
Often they're mounted on the tube base, but they may be on the
signal board (I'm not familiar with the Apple II RGB monitor, I'm
afraid).  If you can locate the video output stages, check the
collector voltages - on the heatsink tabs.  If one is noticeably
lower than the others, measure and/or replace the output transistor.

Email me if you need more details.

BTW be very very careful in there.  The EHT supply and other rails
may remain charged even after you have switched the monitor off,
and can be very dangerous.  Keep one hand in your pocket.

Good luck!

Kris
-- 
Kris Heidenstrom  kheidenstrom@actrix.gen.nz  Wellington, New Zealand
"Destroy 99% of known household pests with pre-sliced, rustproof, easy-
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