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I found a defective bias pot on the 845 amp I am repairing. The pot is not your typical USA made one so I am unsure of its value. The total resistance of the pot that I measured is 17k which is an odd number. The printing on the pot has 33k and some logo or maybe Chinese characters? I am not familiar with 845 amps so I wanted to ask youse guys. cheers, Dak
Follow Ups:
There is little current required to set tube bias, so the value of the pot is just so you don't overload the bias circuit. A 1K ohm pot will cause a -100 volt bias supply to dissipate 100mA which is way too much. A 10K pot with a 10K resistor to limit the ability to set zero bias voltage will present 20K which will draw 5mA This is probably a good level.
Hi Chip and thank you for the recommendation. I will see how that one works and let you know. regards, Dak
You might want to measure the good one on the other amp.
Tre'
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