Marantz SR5009/U1B Service Manual page 83

4.2. Power AMP (AMP PCB)
No audio output.
Protection is activated.
YES
Is the power transistor open or short circuit-
ed?
2SB1560/2SD2390
NO
Is the emitter resistor of the power transistor
open?
0.47Ω
NO
Is the base resistor of the power transistor
open?
22Ω
NO
Is the trimmer potentiometer between the
base of the power transistor open?
1kΩ
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 cur-
rent.
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.
83