On Tue, 11 Nov 2003 18:17:03 GMT, Matt Baum
wrote:

The ProScan 27" set with CTC 169 chassis is over ten years old.
Recently onscreen display started tearing; after an hour or so of
"warmup" it would be OK.
Now it never displays properly. Video modulation comes through.
Horizontal sync is the problem; vertical is OK.
I have the Field Service manual, which says "The OSD horizontal position
is phase-locked with the H-SYNC signal at Pin 23. . . . Components
external to the micro at Pins 25 and 26 set up the characteristics of
the OSD PLL."
Pins 25 and 26 go to 2 resistors and one cap to ground.
This set is a mess to work on. If I am sure that it's one of these
three parts, I'll do it. (Otherwise I'll just forget about the OSD!)

Keep tracing back to the source, this H-pulses is used by many items
including syncing PSU to horizontal rate. Somewhere there's a bad
part or bad glue under a SMD device developed leakage.

Good for you to have real RCA schematics for CTC169 on a CD disc, I'm
still trying to order it from RCA without success.

Cheers,

Wizard


Any suggestions?

Thanks -
Matt Baum
Expert in the obsolete!