XM-2252HX - Sony Car Audio Service Manual (repair manual). Page 8

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Procedure:
1. Rotate the semi-fixed resistor VR101 (R-CH is VR201) com-

pletely in the counterclockwise direction as seen from the com-
ponent side.
• The large variable range of the semi-fixed resistor prevents

flow of excessive current to the output MOS-FET.

• Take note than when an excessive current flows, the protec-

tors operate (both the amber and green lamps light up at the
same time) and the amplifier will stop operating.

TP101

TP102

R168

R150

R249

R268

TP202

C929

C933

C931

C932

C934

C930

C927

C928

VR201

(R-CH)

VR101
(L-CH)

TP201

Digital voltmeter

(L-CH TP102)

(R-CH TP202)

(L-CH TP101)

(R-CH TP201)

+

–

2. Set the input signal setting to non-signal.

3. Apply a 14.4V power supply voltage between the +12V and RE-

MOTE terminals and GND terminal.

4. Adjustments

Connect a digital voltmeter between the two terminals of the
cement resistors R149 and R150 (0.03 

Ω

) indicated as TP101

and TP102 (TP201 and TP202 for R-CH).
Rotate the semi-fixed resistor VR101 and adjust so that the volt-
age between TP101 and TP102 comes between 0.5 mV and 1.1
mV with 0.8 mV as the center.
Adjust R-CH in the same way.

• Perform adjustments carefully as voltage changes are minute.
• When adjusting from the component side, rotating the semi-fixed

resistor control in the clockwise direction increases the idling
current while rotating in the counterclockwise direction decreases
the idling current.