Diagnostics Of Amplifier Section - Pioneer VSX-56TXi Service Manual

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7.1.2 DIAGNOSTICS OF AMPLIFIER SECTION

When DC detection worked (STBY IND. flashes for a long time)
in the protection circuit of foregoing section (or there is not the
speaker output, probably only 1CH), failure (damage) of the
A
power amplifier section is considered.
Because this receiver cannot diagnose the amplifier section by an
electricity state by structure, please diagnose it in the following
steps.
Caution:
When release the STBY (flashes) state before repair, Because
there is the case that the damage progresses when turns the power
on once again, please be careful.
• According to a symptom, perform the following
B
confirmation beforehand.
1. Are not Fuse and IC protector opening it?
2-a. When can turn on electricity, confirm that supply voltage of
the point that can measure is appropriate.
2-b. Furthermore, confirm that voltage ((in a no signal) DC and
the appropriate signal output) between GND and R4621-
4627 (Either of the amplifier side and the speaker terminal
side is possible) (Or remove either of CN4601-4604). And
limit failure CH.
If was able to limit failure CH, diagnose the CH in the following
steps.
C
• Use the tester basically and check that each part is
not damaged (resistance value / open / short circuit).
About parts with damaged possibility, explain FL ch to an
example in order.
1. R4131, 4132 (ACN7107: 0.1 Ω, 1W chip drain resistor)
IC 4102, 4103
(PBD001A: Nch, PBD002A: Pch output POWER MOS Tr.)
2. R4119 (ACN7111: 0.22 Ω .5W ×2 cement source resistor)
R4117, 4118
D (RS1/16S471J: 470 Ω chip resistor for protection circuit)
D4101, 4103
(UDZS10B: 10V Zener diode for current limiting)
D4102, 4104 (1SS355: Small signal diodes same as above)
R4110, 4111 (RS1/16S560J: 56 Ω chip gate resistor)
R4106, 4107
(RS1/16S101J:100 Ω chip IC4101 power filter resistor)
3. IC4101 (PA9009A: Power amplifier with output current bias
Voltage step HIC)
IC4701, 4702
(AEK7023: 200mA IC protector /FAN CONNECTION Assy)
E
4. Q2231, 2232 (2SC4793,2SA1837 TO-220 Tr. /VH TR Assy)
F
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