4.2. Power AMP (AMP PCB)
No audio output.
Protection is activated.
Is the power transistor open or short circuit-
ed?
2SB1560/2SD2390
Is the emitter resistor of the power transistor
open?
0.47Ω
Is the base resistor of the power transistor
open?
22Ω
Is the trimmer potentiometer between the
base of the power transistor open?
1kΩ
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 cur-
rent.
Replace the power transistor.
Replace the transistor.
Replace the resistor.
Replace the emitter resistor.
Replace the base resistor.
Replace the trimmer potentiometers.
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES
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