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5HPX900MalfunctionAnalysisonPowerSupply
5.1CircuitDiagramofSMPS:
5.2MalfunctionAnalysisonSMPS:
Sequence
No.
Circuitto
check
MostProbablyFailures
1
LineFilterand
theSoft‐start
‐ The AC fuse on the rear panel was burnt when connected the
electricity:checktheRT1varistordeviceand theotherlinefilterdevice
toseeifthereisshortcircuit.
‐ RL1 Relay does not pull‐in and the thermistor NPTR1 is
burnt so the
amplifiercannotstart.
‐ The output‐stage circuit is burnt: therefore the input fuse was
destroyed.
‐ Connecting the jumper of 110V and ACI port, the double voltage
rectifierwillletthecircuitworkwith110Vand120Vmainsvoltage.
2
Self‐excited
Circuit
‐ TheamplifiercannotstartandtheInputfuseisburnt:mainlycheckif
the power switch transistor Q29 ~ Q36 is damaged or not. Any one of
transistors burnt will result to no output; then check also the zener
diode DZ10, DZ11, DZ12, DZ13 for
open or short circuit, it will also
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