Nad 3220 Service Manual
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Extracted text from Nad 3220 Service Manual (Ocr-read)
Page 1
m NADSERVICE
MANUAL
3220PE
30209
INTEGRATED AMPLIFIERS
Page 2
ALIGNMENT METHOD
AUDIO SECTION 3220PE/3OZOe
IMPORTANT
Speaker impedance switch should be in 8 ohm position while adjust center
voltage and idiling current.
INITIAL ADJUSTMENT (No load connected)
A. CENTER VOLTAGE
l. Connector DC millivoltmeter to L channel output terminal.
2. Turn on and adjust to 0 V+/-30mV with R4ll(100 ohm). Connect DC milli-
voltmeter to R channel output terminal and adjust R412 to O V+/-30mV.
B. IDILING CURRENT
1. Remove solder short across R455 and R456.
2. Connect DC millivoltmeter across R455 (1 ohm) (output transistor's
collector resistor) and adjust R443 for 26-30mV reading on meter.
Repeat adjustment with R444, connecting meter across R456 (1 ohm).
3. Leave power on for minimum 5 minutes.
FINAL ADJUSTMENT
C. CENTER VOLTAGE
1. Repeat step A about.
D. IDLING CURRENT
1. Repeat step B and adjust with R443,R444 for 30mV reading on meter.
2. After the alignment is finisheed, 1 ohm resistor R455,R456 is shorted
by solder short.
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