4.2. Power AMP (AMP PCB)
No audio output.
Protection is activated.
Is the power transistor open or short circuited?
2SB1560 / 2SD2390
Is the emitter resistor of the power transistor
open?
0.47 Ω
Is the base resistor of the power transistor open?
22 Ω
Is the trimmer potentiometer between the base of
the power transistor open?
1 k Ω
Are any other transistors faulty?
Are any other resistors faulty?
Turn on the power and, check that the voltage of each part is correct and that there is an idling current.
Replace the power transistor.
Replace the transistor.
Replace the resistor.
Replace the emitter resistor.
Replace the base resistor.
Replace the trimmer potentiometers.
Connect the connectors correctly.
Repair the DIGITAL PCB.
4.3. Analog audio
No audio output.
Is a voltage of ± 8V supplied to INPUT PCB
[CN4006]?
Is there an audio signal in INPUT PCB [CN401]?
Reconnect the connectors correctly.
If the malfunctioning channel and function can be identied, check the corresponding signal path.
Repair the ± 8V power supply.
Repair the power amplier.
Is the connector correctly connected to the DIGI-
TAL PCB?
When using the protection pass mode, do not connect speakers to the speaker terminals.
YES
NO
YES
YES
NO
YES
YES
YES
YES
YES
YES
YES
NO
YES
NO
NO
NO
NO
NO
NO
Before Servicing
This Unit
Electrical Mechanical Repair Information Updating
95
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General
Weight and Dimensions
