Scored #5 on list: Pilot TV-37

[dtvmcdonald]

Well, the recap, etc, is done. It works.

I found the vertical centering problem: a magnetic field. I had always had it
on the side ... when I put it bottom down it was the horizontal that was out
of whack (and its control has plenty of range).

But it still needs a repair. If the RF-IF gain control is set very low,
so that less than 1.5 or 2 volts comes out of
the video detector the sync system works fine, but the contrast is too dim.
If I get 3 or 4 volts the contrast is fine but there is a terrible hum in the
video. Higher and the sync clips.

What would cause this hum? It clearly comes from the RF and IF
circuits. I checked the power supplies and they are OK. I tried
adding 100 uF to each of the two 40 uF caps and it didn't change anything.

What could it be? Heater-cathode short? Plain 60Hz pickup?

Its not hum riding on the signal, its hum modulating the signal. The
modulation appears not only at the detector output but at the
RF output of the final IF amplifier.

I have not recapped or re-resistored the RF-IF part.

Any suggestions?
Does anybody know what the peak-to peak video should
be at the output of the detector in normal operation?
None of the data I have for this set give any scope traces.

Doug McDonald