77
4.2. Power AMP (7CH AMP B'D)
No sound is output.
The protector operates.
Is the power transistor open or short circuit?
2SB1647/2SD2560
Is the emitter resistance of the power
transistor open?
0.47Ω
Is the base resistance of the power
transistor open?
22Ω
Is trimmer potentiometer between the base
of the power transistor open?
1kΩ
Is the zener diode and diode which are
connected with the base of a power
transistor short-circuited?
MTZJ4.7B
1SS133
Is other transistor trouble?
Is other resistance trouble?
Turn on power, check that voltage of the section is normal and that idling electric current is fl owing.
Replace the power transistor.
Replace the transistor.
Replace the resistance.
Replace the emitter resistance.
Replace the base resistance.
Replace the trimmer potentiometers.
Replace the Zener diode and the diode.
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES
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