Idling Adjustment - Sony XM-2252HX Service Manual

IDLING ADJUSTMENT

• L-CH (R-CH) Adjusting Method
Connection:
(L-CH TP101)
(R-CH TP201)
(L-CH TP102)
(R-CH TP202)
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.
Adjustment Location:
– AMP/POWER Board – (Component side)
VR201
(R-CH)
AMPLIFIER BOARD
VR101
(L-CH)
Digital voltmeter
+
–
R249
TP202
TP201
R268
POWER BOARD
R168
TP101
TP102
R150
– 8 –
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.
C929 C930
C927 C928
C933
C934
C932
C931