VSX-52TX
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7.1.3 HOW TO DIAGNOSE THE UNIT WITH THE POWER AMPLIFIER SECTION REMOVED
Symptoms that are highly suspected to be
failures inside the Heat Sink Block
Possible causes
1
No power with the STBY LED flashing
DC detection has been activated to prevent further damage to the unit.
Note: Refer to "7.1.2 How to diagnose the Amplifier Section" in the
service manual.
2
The unit turns itself off after "AMP ERR" was displayed on the
FL display. Then it goes into state
1
above.
3
"OVERHEAT" is displayed on the FL display under normal
temperature, then the unit turns itself off.
The peripheral circuits of the posistor inside the Power Amplifier Section
are in failure. Note: A posistor is a kind of thermistor, and its resistance is
approx. 100 ohms at normal room temperature.
4
The unit turns itself off without any indication on the FL
Overloaded amplifier, failure in the overload-detection circuit inside the
Power Amplifier Section, etc.
5
"FAN STOP" is displayed on the FL display, then the unit turns
itself off.
Disconnection of the Fan connector, failure in the fan. (Only for the
models for Europe and those for other than North America and Japan)
Purpose:
When repairing this unit, the large Heat Sink Block obstructs access to some Assys.
If the Heat Sink Block is removed, as the posistor mounted on it is also disconnected, the protection circuit is activated, which
disables failure diagnosis of these Assys while the unit is powered. With the method explained here, the Assys that cannot be
diagnosed while the unit is powered because of the Heat Sink Block can be diagnosed by creating an artificial status of the
posistor's being connected (by connecting a 100-ohm resistor under normal temperature).
Note:
Use this method for diagnosing a failure other than possible failures inside the Heat Sink Block, such as those shown in
the table below:
3
2
4
TRANS 2-1 Assy
• Remove the wires.
• Disconnect the parallel wires.
Procedures:
1
Remove the bonnet and center beam.
2
Remove all the wires from the wire saddle.
3
Disconnect all six connectors connected between the
Amplifier Assy and the SP/PS Assy.
Remove the eight screws that secure the Amplifier
section.
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