Quote:
Originally Posted by Electronic M
You could do the 7 second test, pull one tube in the video chain while it's warmed up, plug it back in 7 seconds later and see if contrast returns fast or slow and repeat till you find your culprit or through all possible tubes that could cause it.
|
After starting pulling tubes and plugging them in and not finding the culprit, I decided to try this: I measured the AGC line bias when it was operating okay. It measured about minus 15 volts. I put my bias box across the AGC line, set it to -15 volts and then switched on the set. The picture popped up normally as I would have expected as the high voltage appeared. I swapped the 6AN8 AGC keyer tube and no change. Something is amiss with the AGC.
I will put the scope to the circuit tomorrow.