Gibson Thor bias?

[boxofknobs]

Does anyone here know how the bias is adjusted in this amp?

[booj]

According to the Gibson service manual, which is available for free at schematics heaven, the bias comes from the high voltage p.t. winding through a 220k resistor and a diode to a 56k resistor to ground. There is a 10? uf cap across the 56k for filtering. The bias voltage is taken off the neg. side of the filter cap. Looks like you could play with either resistor to adjust the bias.

[boxofknobs]

ahh thanks!