Alignment Procedure - NAD C 272 Service Manual

ALIGNMENT PROCEDURE (C272)
I. INITIAL ADJUSTMENT (No load connected)
A. OUTPUT OFFSET VOLTAGE
1. Connect a DC Millivoltmeter to L Channel TP2 (DC) and TP8 (GND).
2. Turn unit "ON" and adjust VR301 (100ohms) to get a reading of 0V+/-30mV.
3. Connect a DC Millivoltmeter to R Channel TP5 (DC) and TP7, then adjust
VR401(100ohms) to get a reading of 0V+/-30mV reading on meter.
B. IDLING CURRENT
1. Connect a DC Millivoltmeter to L Channel TP1 (IDL) and TP3 (IDL), then adjust
VR302 (500 ohms) for 6~7.5mV reading on meter.
2. Connect a DC Millivoltmeter to R Channel TP4 (IDL) and TP6 (IDL), then adjust
VR402 (500 ohms) for 6~7.5mV reading on meter.
II. ISC ADJUSTMENT (WITH LOAD CONNECTED)
1. Connect a DC Millivoltmeter to Power Board CB725, and connect 4 ohms load to
both L&R speaker output terminals. Then feed 20kHz signal to Fixed In RCA.
2. Turn unit "ON" and try to get 15W on speaker output terminal. Then adjust VR701
(82kohms) to get a reading of 0V+/-10mV.
3. Change the load to 8 ohms and try to get 160W on speaker output terminals.
Then adjust VR701 (82kohms) to get a reading of 1.4V+/-30mV.
III. FINAL ADJUSTMENT
Repeat procedure A and B for offset voltage and idling current alignment respectively.
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