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The ECC-82 was working even with the shorted heater/cathode because the cathode of that section is at DC ground anyhow. *I meant to also say that the filament supply is isolated.* It just injected some hum, which I had noticed. There had been a very small slow weave of the dot pattern. It would reduce the feedback in the horizontal oscillator a little bit.
I put in a 12AU7 that I had taken out of the set. It's at the low end of the good scale, nearly in the weak when I test it. Using it I get insufficient horizontal width and fold-over on the right. I hope the ones I ordered are strong.
I was surprised that it performed so poorly with this tube so I did some more checking. I found one resistor out of tolerance by 20%. It's a 10% resistor. Probably shouldn't matter too much but I'll replace it. Another one is off by 20% and one is just the wrong value. It looks like someone replaced it using the schematic from the previous production change and not the current one for this chassis. This ends up shifting the grid bias on the Horizontal Discharge half of the 12AU7.
The 6BD5 horizontal output tube seems strong and I didn't find anything wrong in that section.
John
Last edited by jeyurkon; 01-31-2010 at 12:05 PM.
Reason: added comment
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