[RCA tv ctc169] venetian blind effect when cold

[MAC]

Working on this RPTV.
When cold, the display appears to be out of H sync
Several horizontal parts of frame displayed and rolling up and down.
after turning off and on for about 5 minutes, the picture finaly
stabalizes. Just before stability, the frame appeas to have a venetian
blind effect.

Two caps in PWM ic in PS were replaced.
The 15 volt Standby Diode (4118) was replaced.
Also blue box cap near HOT was replaced.
No improvement.

Has anyone seem this symptom before.

The H drive signal has an extra negative going spike, but it is still there
when the pic looks good.
Doug

 

[BWL]

Have not seen this particular symptom, but check inside the PIP module for
partially melted "buttons" used to prevent case to component contact inside
module. This stuff becomes conductive/corrosive, and I've seen video and
blanking problems as a result.

 

[Jason D.]

Have not seen this particular symptom, but check inside the PIP module for
partially melted "buttons" used to prevent case to component contact inside
module. This stuff becomes conductive/corrosive, and I've seen video and
blanking problems as a result.

Oh yeah, those rubber brown button sudden melted and did many strange
things what I did was study the schematic carefully and remove the PIP
circuits and install key components to reroute the signals. Uses same
PIP and non-PIP adapter layout, depending on components installed.

I took a non-PIP from scrapped 169 adapter and swapped it in and
removed PIP on that 169'er chassis, saving the 35" set. Worked like a
treat. There's no special changes to the micro.

Cheers,

Wizard