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4.2. Power AMP (MAIN UNIT)
No sound is output.
The protector operates.
Is the power transistor open or short-
circuited?
2SB1560/2SD2390
Is the emitter resistance of the power
transistor open?
0.47 Ω
Is the base resistance of the power
transistor open?
4.7 Ω
Is the trimmer potentiometer between the
base of the power transistor open?
1k Ω
Is other transistor trouble?
Is other resistance trouble?
Turn on the power, check that voltage of the section is normal and that idling electric current is
owing.
Replace the power transistor.
Replace the transistor.
Replace the resistance.
Replace the emitter resistance.
Replace the base resistance.
Replace the trimmer potentiometers.
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES