4.2. Power AMP (AMP PCB)
No audio output.
Protection is activated.
Is the power transistor open or short cir-
cuited?
2SB1647/2SD2560
Is the emitter resistor of the power transis-
tor 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?
1k 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.
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES
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