Diagnostics Of Amplifier Section - Pioneer VSX-55TXi 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
A
speaker output, probably only 1CH), failure (damage) of the
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.
B
• According to a symptom, perform the following
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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