AppleColor RGB all-red display

[dog_cow@macgui.com (D Finnigan)]

I was fiddling with my AppleColor RGB (for the IIgs) yesterday, and I
managed to break it.

I was trying to figure out why the voltage to the screen was increasing,
thus making the intensity slowly ramp up as the electronics got warmer over
about 10 minutes.

I measured voltage across a 4.7k Ohm resistor on the CRT board (the one that
connects to the neck of the CRT) and it was about 50 volts. I then measured
across the identical (?) 4.7k Ohm resistor on the left side of the same
board. This is where things went wrong. I have an analog multimeter, and
when I connected the leads, the needle went back, like negative voltage. I
assumed this meant that I had the leads the wrong way around, so I reversed
them. I got a spark, a zap, and a nasty smell. A second later, the display
went all red. I turned off the monitor.

I searched the Apple II FAQs, and found in the Monitors, question 008-
"Suddenly my monitor has an all-blue (all-red, etc.) screen! How do I fix
this?"

Well, I measured the resistance across all three inductors, and they were
all about 10k Ohms. I powered on the monitor and measured the voltage drop,
which was negligible (the needle barely moved).

So, now I must assume that some other component blew up and made the nasty
smell. Any ideas? I'm not really good at doing electronics, so I'm going to
have a graybeard help me with the repairs.

-- 
]DF$
Mac GUI Vault - A source for retro Apple II and
Macintosh computing.
http://macgui.com/vault/