Klipsch SW12-I - Troubleshooting Guide; Fuse Blows Without Output; Low Output Level from Speaker Inputs

Klipsch Subwoofer Amplifier Service Manual KSAMM-002a
TROUBLE SHOOTING GUIDE
CAUTION!
Lethal voltages are present and exposed when cover is off of amplifier.
1
Only qualified service technicians should attempt to repair or align subwoofer amplifiers.
PROBLEM
POSSIBLE CAUSE
1
Blows fuse with nothing connected 1 Check output transistors on power board.
to the output. Replace transistors that are shorted.
2 Check driver transistors on filter/driver board.
Replace transistors that are shorted.
3 Check U7 and U9 for shorts.
4 Check bridge rectifier in power supply circuit.
5 Check transformer.
6 Check filter capacitors. C21,C22, C23, C24, C44, C45,
C46, and C47.
7 Check for pinched wires going to and coming from
the transformer.
2 Low output level using speaker level 1 Check inputs for correct polarity from source.
inputs. If polarity is not correct, the signals will be 180° out of phase
and will cancel each other out causing a low output.
2
Check R79 and R80.Should read 91K:.
3 Check U13.
4 Check for proper signal flow using schematic.
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