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RE: 211 Bias overload.......

Posted by Palustris on July 24, 2024 at 07:48:16:
It's not obvious where the fault lies and thoroughly checking out the amplifier voltages to troubleshoot means exposing your self to dangerous voltages. Notice the plate voltage on the 211 is 960V! So I would start with the unit unplugged and the power supply caps discharged. Start with the bias supply: measure the resistance of R8, R9, R10 and VR1. Ensure each of these is the correct resistance and that the pot, VR1, has a smooth change of resistance for the entire sweep of the wiper. If you are lucky, then one of these components will be at fault.

Otherwise you will need to check the voltages throughout the amp. Always turn the unit off, apply the DVM leads to the component under test, and turn on the amp. Having multiple DVMs makes the job much more rapid.