Quote:
Originally Posted by Kevin Kuehn
You can do that but you'll be spending a lot more time getting things corrected. Right now you know the grid of the horizontal output tube is under biased, and it's pulling more plate current than intended. Besides paper caps it's possible the 560pf mica grid coupling cap is leaking positive voltage from the horz oscillator onto the horz output grid. You could try pulling the 6BG6 and see there's any residual voltage remaining on pin 5 of it's socket. Speculating we can assume the higher than normal plate current the 6BG6 is drawing could be pulling a B+ down few volts. That happens because these old sets don't have much if any voltage regulation. And the horz out is probably the biggest consumption of power.
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Thanks as always Kevin. Do you mind expanding on this a bit for me? I thought bias voltage just turned a tube on and off. There's a ramped relationship between bias on the grid and the plate output? Is a biasing voltage always a negative voltage? Since -4.8V is a higher voltage than -33 volts DC does that account for the higher current on the plate? Confused as usual by the details. Can you explain to me how a 6BG6 works other than the filament voltage?
11-17-2025, 12:12 PM
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