Set comes on from a cold start and plays for a few seconds then goes to static. Tubes are OK. What could be wrong???

:Set comes on from a cold start and plays for a few seconds then goes to static. Tubes are OK. What could be wrong???

Hi John,
Seem like it could be Silver Mica Disease. When the static starts, measure the grid of your IF tube and then the Plate of the second detector. If you are lucky you won't see the static in the measurement. If you do, Silver Mica is the likely culprit. If you don't a capacitor in the IF may be the problem.
Eventhough tubes test good, they still may fail in the radio. I just found one here, a 12AL5. It tests good, but one filament glows bright red while the other is dim. Not good.

Best Regards,

Bill Grimm