Wiring dpdt gain switch help

D'tar

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Yes, There are few ways the bias could fail and now you are protected from a couple of them!😉
 

matt117

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Yes, There are few ways the bias could fail and now you are protected from a couple of them!😉
Hey wondering if you can help me out once again.
I have no bias range showing up on my probe points at the jumper mod.

0615D87A-1316-4F72-97E5-43C4B115E7DB.jpeg
 

D'tar

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Hey wondering if you can help me out once again.
I have no bias range showing up on my probe points at the jumper mod.

View attachment 1000469

Matt,

I was on a camping trip with super limitted, read only, phone service. Lol

Where are your probes connected? If you havent already, You can pull the rectifier tube while you figure out the bias voltage.

amp off/unplugged caps drained, Black probe to chassis, red probe to powertube control grid, reading ohms, what do you have at full clockwise and full ccw?
 

matt117

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No worries!
It is in bias point probes. With the 1ohm resistors on pin 8 to ground giving me mv instead of measuring with current meter. In that video those were the readings I got. Just around 0mv a little negative and little positive values were available.
Matt,

I was on a camping trip with super limitted, read only, phone service. Lol

Where are your probes connected? If you havent already, You can pull the rectifier tube while you figure out the bias voltage.

amp off/unplugged caps drained, Black probe to chassis, red probe to powertube control grid, reading ohms, what do you have at full clockwise and full ccw?
 

D'tar

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I must have been brain farting as your voltage will not vary at the top of the divider. Youll have to remove the jumper, you can replace it with a resistor say 100k to achieve the initial thought. Appologies. I'm surprised no one else stepped in to point out my error.
 
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andrewRneumann

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I must have been brain farting as your voltage will not vary at the top of the divider. Youll have to remove the jumper, you can replace it with a resistor say 100k to achieve the initial thought. Appologies. I'm surprised no one else stepped in to point out my error.

You know I saw that layout, scratched my head, assumed you knew what you were doing, and moved on!
 




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