According to the owner's manual, the power tube bias setting is in spec when the voltage measured across the 0.5 ohm resistor is set at 130mV using a digital voltmeter after the amp has been sitting idle with no signal input for at least 15-minutes. Adjust the trimpot using a non-metalic screw driver or "tweaker tool". I adjust the bias to be close after the first minute of warm up then adjust it again after the amp has been sitting idle for about 10-minutes. I make one final and precise adjustment after the amp has been sitting idle for about an hour. There is one bias adjust trimpot per channel. Be sure to use a non-metalic screw driver and remove any jewelry or watches before working inside the amp. The voltages inside are lethal so be careful! The process is more involved if you also replace the driver tubes. Click the photo above to move to the next page.
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