Adjustment; Protection Circuit - Pioneer M-AX10 Service Manual

6. ADJUSTMENT

6.1 IDLE CURRENT ADJUSTMENT
The idle current is adjusted in two steps: coarse and fine. Note that
the adjustment value for fine adjustment depends on the elapsed
time from the coarse adjustment.
For the points to be adjusted or measured, see Table 6-1 and Fig. 6-
1.
For the adjustment timing and values, see Table 6-2.
Be sure to turn VR501, VR502, VR601 and VR602 fully counter-
clockwise before turning the power on.
Table 6-1 Adjustment points of idle current
Channel L High ch L Low ch R High ch R Low ch
Adjustment
VR501
point
CN505
Measurement
point
Between Between
pins 1 and 2 pins 3 and 4
Table 6-2 Adjustment values of idle current
Adjustment Timing
Coarse
Power ON immediately
Adjustment
More than 5 min.
and less than
More than 10 min.
Elapsed and less than
Fine time from
Adjustment the coarse
More than 15 min.
adjustment
and less than
More than 30 min.
VR302
L Low ch
DC OFFSET ADJ
VR301
L High ch
DC OFFSET ADJ
VR502
L Low ch
Idle Current ADJ
VR501
L High ch
Idle Current ADJ
VR502 VR601 VR602
CN505 CN605 CN605
Between Between
pins 1 and 2 pins 3 and 4
Adjustment value
(Pin voltage)
14.5mV ± 1.0mV
16.0mV ± 0.5mV
10 min.
15.5mV ± 0.5mV
15 min.
15.0mV ± 0.5mV
30 min.
14.5mV ± 0.5mV
CN505
Fig. 6-1 Adjustment and measurement points
6.2 DC OFFSET ADJUSTMENT
Adjust the DC offset with the power on immediately before fine
adjustment of the idle current.
For the points to be adjusted or measured, and the adjustment values,
see Table 6-3 and Fig. 6-1.
Table 6-3 DC offset adjustment method
Adjustment
Channel
Point
L High ch VR301
L Low ch VR302
R High ch VR401
R Low ch VR402
6.3 OPERATION CHECK OF THE

PROTECTION CIRCUIT

While supplying a sine wave of 1 Hz, 1.2 Vrms in DUAL MODE,
with ATT.THROUGH OFF, increase the volume level and check
that the protection circuit activates before the level reaches the
maximum value. It works about before twelve o'clock position.
CAUTION : This check mode may damage the speaker(s) when it
is connected to the output terminal. It is recommended
that output terminal is open at this check mode.
Rear Side
Front Side
M-AX10
Adjustment
Measurement Point
Apply channel speaker
terminals (Red, Black)
VR402
R Low ch
CN605
DC OFFSET ADJ
VR401
R High ch
DC OFFSET ADJ
VR602
R Low ch
Idle Current ADJ
VR601
R High ch
Idle Current ADJ
Value
0V ± 10mV
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