Idling Current; Meter Adjustment - Marantz MA-9S2 Service Manual

4. The voltage of the idling current will be 10mV(50mA) for
each.
The current value is stabilized by about 10mV (50mA) in
about 30 minutes after turn on power.
Refer to the following graph for the idling current and time
after turn on power.
5. 3 minutes after turn on power, adjust the idling current to
8mV (40mA), after 10 minutes, it checks becoming the
value of about 10mV (50mA).
mV
(mA)
12
(60)
10
(50)
8
(40)
6
(30)
4
(20)
2
(10)
0 5

Meter Adjustment

1. Connect an oscillator to the input terminal
UNBALANCED-1 and connect an AC voltage meter to
the speaker output terminals. ATTENUATOR is set to 0dB
and no load is connected to the speaker output.
Turn the variable resister R917 on the PWB (P801)
counterclockwise to the end.
2. Turn on power and adjust output power (output frequency
1kHz) of the oscillator to set the speaker output voltage to
15.5V.
3. When the speaker output voltage becomes 15.5V, adjust
the variable resistor R917 on the PWB P801 to set the
meter -10dB. (Output voltage 15.5V means 30W for 8Ω,
60W for 4Ω.)
4. Assuming this point as 0db, decrease the output power of
the oscillator like 0dB → –20dB → –30dB→ –40dB, the
meter will show the corresponding

Idling Current

10 15
METER 8 OHM LOAD
0 dB 300 W
-10 dB 30 W
-20 dB 3 W
-30 dB 0.3 W
-40 dB 0.03 W
3
4.
30 10mV 50mA
5. 3
10 10mV 50mA
20 25
1. UNBALANCED-1
AC
ATTENUATOR 0dB
P801 R917
2. ON
3. 15.5V
10dB P801
15.5V 8
4. -10dB
-20dB -30dB - 40dB
4 OHM LOAD
600 W
60 W
6 W
0.6 W
0.06 W
10mV 50mA
8mV 40mA
(minutes)
30 35
15.5V
1kHz
-
R917
30W 4 60W
0dB