NAD -90-sch free download

File name nad-90-sch.pdf

w 0 w I LU I 2. BIAS ADJUSTMENT PROCEDURE The proper bias adjustment is most important to assure correct performance of the amplifier. Bias adjustment is necessary if any of the transistors are replaced in the power amplifier circuitry or the amplifier exhibits overheating of the output transistors under normal operating condisions. INDICATOR ADJUSTMENT REMARKS -----:--.--..------------. -- .-t---------- --- - DC Voltmeter VR6O1a, b (1 Kohm) Adjust for 0.006 -- 0.015 V across - R624a, b (0.33 ohm) with NO SIGNAL REMARK: Bias can also be adjusted by using a line wattmeter. Adjust the VR6O1a and VR6O1b to the point at which the line wattmeter shows very slight increase. 3. ADJUSTMENT AND CHECK POINTS R624b R624a VB 601 b v H 60 7. 0027 PRE-AMP BOARD (TOP VIEW)