Bias issue with new 100w build - need help

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tjohn1968
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Bias issue with new 100w build - need help

Post by tjohn1968 » Sat Jul 02, 2022 12:40 pm

I have just completed a 100w build and checking the voltages and busing the tubes. My V4 and V5 tubes biased closely to 35 millivolts. My V7 tube is biding close to 35 but my V6 tube was reading over 100 millivolts.

Not sure where to start figuring this one out. Any help would be appreciated.

Thanks,

danman
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Re: Bias issue with new 100w build - need help

Post by danman » Sat Jul 02, 2022 6:42 pm

Remove power tubes and power up the amp. Check the DC bias voltage on pin 5 of each power tube socket. It should be somewhere in the area of -30vdc to -50vdc. Make sure all four sockets show the same bias voltage. If they all read the same voltage, the most likely culprit is a bad power tube. If your v6 socket shows a different bias voltage, you probably have a bad connection caused by a cold solder joint.

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