DC Volts on tubes

royb3988
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DC Volts on tubes Feb 3, 2020 19:26:35 GMT -5

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Post by royb3988 on Feb 3, 2020 19:26:35 GMT -5

Greetings...

Amp is a 1967 Fender DUAL (BLOCK LETTERS), 4ohm output transformer Showman, tubes are 6L6GC Svetlanas, bias set at .038 mA

If I measure 465 VDC for Plate voltage and 464 VDC for my Screen Grid voltage...are those numbers an indication of a problem...being so close to each other?

Thanks,

rb3988

pdf64 Wholenote Posts: 556	DC Volts on tubes Feb 4, 2020 20:01:01 GMT -5 via mobile Home Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by pdf64 on Feb 4, 2020 20:01:01 GMT -5 Not at all, it’s a non issue. What’s the Vac across the heaters and at the wall outlet?

royb3988 Quarternote Posts: 4	DC Volts on tubes Feb 4, 2020 23:49:27 GMT -5 Home Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by royb3988 on Feb 4, 2020 23:49:27 GMT -5 Hello pdf64... Across pins 2 and 7 I get 6.56 VAC. Not sure what measurement you mean by the wall outlet? It's standard 120VAC...I measure 118.9VAC on my VOM Thanks, rb3988

pdf64 Wholenote Posts: 556	DC Volts on tubes Feb 5, 2020 4:43:56 GMT -5 via mobile Home Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by pdf64 on Feb 5, 2020 4:43:56 GMT -5 Great, all good! Those 2 measurements are crucial as they set the context for all others. If they’re off, everything else is wrong.

royb3988 Quarternote Posts: 4	DC Volts on tubes Feb 5, 2020 19:56:23 GMT -5 Home Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by royb3988 on Feb 5, 2020 19:56:23 GMT -5 Thanks pdf64, Just to confirm: the readings on the tubes were taken with one probe on pin 2 and the other probe on pin 7, correct? Thanks, rb3988

pdf64 Wholenote Posts: 556	DC Volts on tubes Feb 7, 2020 14:45:09 GMT -5 via mobile Home Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by pdf64 on Feb 7, 2020 14:45:09 GMT -5 Yes, correct 😀 Ideally it will be within 5% of 6.3V, certainly don’t want it outside of a 10% tolerance, eg over 6.9V.
	Last Edit: Feb 7, 2020 14:48:23 GMT -5 by pdf64

Post by royb3988 on Feb 3, 2020 19:26:35 GMT -5

Post by pdf64 on Feb 4, 2020 20:01:01 GMT -5

Post by royb3988 on Feb 4, 2020 23:49:27 GMT -5

Post by pdf64 on Feb 5, 2020 4:43:56 GMT -5

Post by royb3988 on Feb 5, 2020 19:56:23 GMT -5

Post by pdf64 on Feb 7, 2020 14:45:09 GMT -5