Alto PBM8.250 MKII Service Manual page 22

7. PBM8.AMP (PBM500, PBM8.250) BIAS Adjustment Procedure
1. Test Instruments
1) Digital multi-meter
2. Procedure and Specification
1) No signal input to CH1 (J1-11) and CH2 (J2-11): switch on the power
supply on the front panel, three green LEDs will light up (D2, D1-16, and
D2-16); moreover, D1-4 and D2-4 will light up dimly. Measure R1-11,
R2-11(+15V)...R2-12, R1-12(-15V) by using the multi-meter.
2) No the signal input, and adjust R1-16(CH1) and R2-16(CH2) to set the
values of R1-17/R2-17 as 125±2mV (PBM8.250)/130±2mV (PBM8.500).
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