Panasonic with barcode picture

[DanKurts]

Originally Posted by mstaton

Doubtful if it's power supply. Main board or driver(digital) board. Sounds like a bad solder joint. Take the butt end of a screwdriver and gently push on the boards while its having the issue and see if anything improves or changes. Please be careful around the power supply and y and z boards. nasty shock hazard.

mstaton, Zenith26kc20
Thanks for all the suggestions. Grew up in my dad's TV shop, learned about getting zapped the hard way! I did the wiggle poke around a bit once before to see if there was a loose connector or wire, but I'll give it a more thorough check. Found the factory service manual for it on line, had a lot of detail on the theory, but was missing the pages for the skiz and block diagrams. Kind of hard to figure out which boards actually sync up all the timing, which was what I figured was a logical starting point.
Agree about the cold solder joints. Reminds me of the cold spots on the little PC boards they used to use on the CRT's. The heater pins would go cold over the years. Set would come on, warm up, heaters would go off, after 5 minutes or so they would cool down and reconnect, picture would slowly come back. Old RCA and Magnavox sets from the mid 60's were famous for the video output tube sockets doing that, too.
In any case, having fun figuring it all out!
Thanks again.
Dan