The sure fire fix is to replace the weak picture tube. Common on Sony
sets with the AKB circuit. A slight increase in G2 voltage will buy
some time, but it is pretty much time to start shopping for a new set.

Do a google groups archive search here for Sony blanking, AKB, blinking
video, etc.

David

Dave Miller wrote:
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