Pioneer SX-1080 Service Manual

9.4 POWER AMPLIFIER
Center Voltage Adjustment
1. Connect a DC voltmeter between power ampli¬
fier ass’y (AWH'071) L-ch terminal 10 and
ground .
2. Check if the voltage between terminal 10 and
ground is OV, adjust to OV with VRa*
3. When OV cannot be obtained by performing
the adjustment of item 2 above, cut the jumper
wire shown in Fig. 14 and adjust to OV with
VR2.
4. Thr R-ch also uses the power amplifier ass’y
(AWH-071). Check and adjust this channel in
accordance with items 1 ■ 3 above.
Idle Current Adjustment
1. Connect a DC voltmeter between terminals
13-23 of the power amplifier ass’y (AWH-071)
L-ch side.
2. Set the power switch to “ON”, wait 10
minutes, and then check if the DC voltmeter
reads 30mV. If it doesn’t read 30mV, adjust
to 30mV by turning VRi,
3. The R-ch also uses the power amplifier ass’y
{AWH-071). Check and adjust this channel in
accordance with items 1 - 4 above.
9.5 METER AMPLIFIER
1. Push speaker selector switch button “A”.
2. Connect an AC voltmeter to speaker output
terminal (A).
3. Apply a IkHz sine wave to the input terminals,
and adjust the input for an AC voltmeter
reading of 31V.
4. Adjust VRi (L) and VRj (R) for a meter
indication of OdB, as shown in Fig. 15.
Fig. 14 Power amplifier adjustment
<m
©
Top view with bonnet removed
Power supply assembly
VRj
VR-
©
w
©
©
1
Meter amplifier
Front panel
Fig. 15 Meter adjustment
26

Pioneer SX-1080 Specifications

General

Total Harmonic Distortion	0.1% (at rated power)
Tuning Range	FM, MW
Damping Factor	30
Input Sensitivity	2.5mV (MM), 150mV (line)
Output	150mV (line), 1V (Pre out)
Speaker Load Impedance	4Ω to 16Ω
Frequency Response	5Hz to 100kHz
Signal to Noise Ratio	90dB (line)
Semiconductors	4 x FET, 6 x IC
Power Output	120 watts per channel (8 ohms, 20Hz-20kHz)