Denon AVR-E400 Service Manual page 90

4.2. Power AMP (AMP UNIT)
No sound is output.
The protector operates.
YES
Is the power transistor open or short-
circuited?
2SB1560/2SD2390
NO
Is the emitter resistance of the power
transistor open?
0.47Ω
NO
Is the base resistance of the power
transistor open?
22Ω
NO
Is the trimmer potentiometer between the
base of the power transistor open?
1kΩ
NO
Are the zener diode and diode which
are connected with the base of a power
transistor short-circuited?
MTZJ3.3B
1SS133
NO
Is other transistor trouble?
NO
Is other resistance trouble?
NO
Turn on the power, check that voltage of the section is normal and that idling electric current is
flowing.
YES
Replace the power transistor.
YES
Replace the emitter resistance.
YES
Replace the base resistance.
YES
Replace the trimmer potentiometers.
YES
Replace the zener diode and the diode.
YES
Replace the transistor.
YES
Replace the resistance.
90