Thanks to all for the replies.

Let me see if I understand this: when a CRT starts getting weak, the
resistance in it goes up, so it doesn't draw as much current from the
flyback as the compensation circuit thinks it should. Since it can't raise
the tube voltage anymore without risk of x-rays, it shuts down. Is that
sort of correct?

I appreciate the help. It is too damn bad, because that was a really nice
TV in its day.

Oh well

Dave Miller


"Jerry G." wrote in message
...
In this model, if the CRT is going defective, this effect will occur. It
is a type of protection for the high voltage, and X-Ray emissions.
Changing the CRT should fix the fault, but is not a feasible option.

--

Jerry G.
======

"Dave Miller" wrote in message
...

Hello all --

I have a Sony KV-32XBR48 that was manufactured in October, 1997. The
problem is that the picture blinks on and off at about a one second
rate.
The audio is constant, and the problem happens whether the video source
is
from the tuner or a video input. One other symptom is that it seems to
me
that the time for the picture to come on the first time is much longer
than
it used to be, and when the picture first comes on, it only stays on for
a
brief time, and stays off for quite a while. As the set warms up, it
gets
to about one second on, and one second off.

I have spent a fair amount of time looking at the set, and what I see is
that the video signal looks good going into IC351 which is a Sony
CXA2025 Y
chroma/jungle IC. The RGB video drive signals out of this chip change
directly as the picture blinks on and off. One other thing is that pin
26
of this same chip changes with the picture blinking on and off. This
seems
to make sense since it appears to be essentially a flyback transformer
current sense. Both the picture on and picture off voltages at pin 26
are
much higher than the schematic from SAMS indicates it should be. The
only
way I see for the voltage to get lower is to draw more current through
the
flyback. The voltage I see is about 9 volts when the picture is off,
and
about 8 volts when the picture is on. (I can get more precise readings
if
that is helpful.) The SAMS predicted voltage at that point is 1.6
volts.

I have checked power supply voltages, and they seem reasonable. None
of
them fluctuates with the picture on/off. I have resoldered the joints
at
the flyback transformer, but no others.

Any tips at this point would be greatly appreciated.

Thanks in advance

Dave Miller
Tucson, AZ