Audio Pro B1.39 - Bias Adjustment Procedure; Bias Setting Guide; Component Mounting Note

Bias adjustment B1.39
Input signal 50-60Hz.
Connect a 4Ω load to output.
Adjust output level to 3.5-4V RMS and leave the amp to warm up for about 20
minutes.
Set output level to 0 and adjust VR1 for 1.5-3mV after about 1 minute.
Note! Check that Q07A (2SC3421) has a perfect contact surface against the cooling
flange.