How To Diagnose The Product With The Power Amp Block Removed - Pioneer VSX-AX4AVi-S Service Manual

1

7.1.10 HOW TO DIAGNOSE THE PRODUCT WITH THE POWER AMP BLOCK REMOVED

A
The failure in the Power Amp Block is suspected as shown in the table below.
Symptom that is highly suspected to be caused
by a failure in the Power Amp Block
1 The power cannot be turned on, and the MCACC LED is flashing. The DC detection circuit is activated in order to prevent extension of the
2 The unit is shut down after "AMP ERR" is displayed on the FL
display. Then the unit goes into the state described in 1 above.
3 "OVER HEAT" is displayed on the FL display.
4 The unit is shut down without an error message on the FL
display. Then the PHASE CONTROL LED flashes.
B
Failure diagnosis with the power on is not possible for some board assys, because the large Power Amp Block lies in the way.
However, if the Power Amp Block is removed, the thermistor connected to the Power Amp Block is disconnected, which will
activate the protection circuits.
To enable failure diagnosis of those board assys, after the Power Amp Block is removed in the manner described below.
[Procedures]
1
Remove the bonnet by removing the 22 screws.
2
C Remove the two screws.
3
Remove the four screws.
4
Disconnect the six connectors and one jumper.
5
Disconnect the flexible cable.
4
×7
D
E
3
F
236
1
2
3 3
2
2
3
VSX-AX4AVi-S
2
3
failure.
Note: See "7.1.11 Failure Diagnosis of the Power Amp Block."
The posistors (TH5001 and TH5301) in the Power Amp Block are open.
Note: The resistance of the thermistor at normal temperature is about 330 ohms.
Power Amp overloaded, defective overload-detection circuit in the Power
Amp Block, etc.
6
Remove the nylon rivet.
7
Remove the POWER PROTECT Assy from the Power Amp
Block.
8
Remove the Power Amp Block.
P
POWER PROTECT
Assy
5
The POWER PROTECT Assy can be easily removed
with no load applied to the connectors if you pull out the
board by pushing on it at its center from the rear.
Note:
To prevent an electric shock hazard, after removing the Heat Sink
Block, discharge the condenser of the ±VL line, by discharging
CN4101 or CN4102 on the SP/PS Assy, using a discharging
resistor. (It is recommended to make a resistance of 100 ohms or
more in the series-parallel connection, using four or more
discharging resistors of 100 ohms, 3 W.)
3
4
Possible cause
6
7
8
7
7
4