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RCA 27 inch: all red, now all foggy

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Ramone

Jan 1, 1970
0
Hi,

This concerns a 1997 RCA CRT, model # F27680GY.

I had been watching TV for a couple of hours when I heard a small pop from
inside the TV. Within 5 seconds the image went from a pink haze to solid
red. I could see absolutely nothing except red but no problems with the
audio or with changing channels. I did some googling on the topic and, long
story short, I replaced the "red driver" transistor on the socket/akb/svm
board.

So, the TV is "watchable" now but there are still some symptoms...

- There is a gray haze over everything. Even on max contrast and max black,
things that should be black are appearing as light gray. The brights are not
any brighter than usual.
- There are 24 evenly spaced faint thin blue horizontal lines crossing the
screen (these lines were there even during the solid red problem)
- Every time I turn off the unit, there is an intensely bright 2"
halo/rainbow in the middle of the screen for 1 second.
- When I turn the unit off and then on again, right before the image
appears, there is a bright blue horizontal line in the middle of the screen
for 1 second.

Does anyone know if there's another small part to obviously change or is a
whole board fried or worse? Any help would be greatly appreciated.

Thanks!
Ramone
 
P

Phil Bowser

Jan 1, 1970
0
The "popping" you heard was probably the CRT arcing back through the
neck, which shorted one of the output transistors, which you have
replaced... Also, the G2 voltage / drive level has obvioulsly changed
radically, either by the technician "bumping" the adjustment on the G2/Focus
block (back of IHVT) during servicing, or the CRT is simply failing,
developing G2 leakage internally (possibly gassy) that requires readjustment
of the G2. Either heavy drive to one or more of the output transistor (like
the one you replaced) OR excessive G2 drive voltage can cause retrace lines
(and a washed-out picture...blacks aren't black, but some shade of gray).

As far as "Will the CRT arc again?" - I would simply replace the
transistor, and readjust the proper G2, Focus, and grayscale according to
the service literature, and play it a couple of days to see.. .Even then,
there's no guarantee that down the road a week or month, etc. it may arc
again, and repeat the process...
 
R

Ramone

Jan 1, 1970
0
Thanks Phil!

Adjusting the G2 downwards helped a lot. Things are still not perfect. My
blacks are more like dark green/blue and the red highlights have that
bleeding effect. In general, the picture just doesn't have the nice contrast
and "color fidelity" that it had before, despite all my attempts at
adjusting color, tint, contrast, etc. Seeing as I have other unrelated
intermittent problems with this set (probably due to cold solders that many
other people have mentioned for the CTC197), it may be time to buy a new 27"
which have substantially dropped in price... unless you have another idea...
Thanks again!

Ramone
 
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