RCA P52937YX2, PTK195M26B
Symptom: tv would play perfectly for about 40 minutes and then begin
pulling
in vertically from bottom. After closing up about 8 inches there would
be
compression in the middle of the raster and raster would go off. Audio
was
still ok.
Looked like easy thermal intermittent to find. But nooooo. Cooling
capacitors near the T-chip (U16201) and the T-chip itself would slowly
bring
the raster back. We used freeze spray on a Q-tip to try to pin it down
and
still got slow response. Changed T-chip (we used a socket) and several
electrolytics in the area but did not help. Scoping the vertical out of
the
T-chip (pin15) showed the waveform decreasing.
Fix: Resolder several surface mounted components between the T-chip
pins on
pc side of board. Components were near pins 15 and 16. We think they
included R14520 and possibly C14501 and C14503. We also resoldered the
ground tabs between the T-chip pins. Touching those areas with freeze
spray
on a Q-tip gave immediate response.
Jeff Smith
Smith TV Service
Symptom: tv would play perfectly for about 40 minutes and then begin
pulling
in vertically from bottom. After closing up about 8 inches there would
be
compression in the middle of the raster and raster would go off. Audio
was
still ok.
Looked like easy thermal intermittent to find. But nooooo. Cooling
capacitors near the T-chip (U16201) and the T-chip itself would slowly
bring
the raster back. We used freeze spray on a Q-tip to try to pin it down
and
still got slow response. Changed T-chip (we used a socket) and several
electrolytics in the area but did not help. Scoping the vertical out of
the
T-chip (pin15) showed the waveform decreasing.
Fix: Resolder several surface mounted components between the T-chip
pins on
pc side of board. Components were near pins 15 and 16. We think they
included R14520 and possibly C14501 and C14503. We also resoldered the
ground tabs between the T-chip pins. Touching those areas with freeze
spray
on a Q-tip gave immediate response.
Jeff Smith
Smith TV Service
