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4.2. Power AMP (AMP PCB)
No audio output.
Protection is activated.
YES
Is the power transistor open or short circuited?
2SB1560 / 2SD2390
NO
Is the emitter resistor of the power transistor open?
0.47 Ω
NO
Is the base resistor of the power transistor open?
22 Ω
NO
Is the trimmer potentiometer between the base of
the power transistor open?
1 k Ω
NO
Are any other transistors faulty?
NO
Are any other resistors faulty?
NO
Turn on the power and, check that the voltage of each part is correct and that there is an idling current.
YES
Replace the power transistor.
YES
Replace the emitter resistor.
YES
Replace the base resistor.
YES
Replace the trimmer potentiometers.
YES
Replace the transistor.
YES
Replace the resistor.
81
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