DAEWOO ELECTRONICS KOR-637V, Service Manual

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20
(TROUBLE 3) No microwave oscillation even though fan motor rotates.
TROUBLE SHOOTING GUIDE
CONDITION
CHECK RESULT
Continuity
Continuity in
backward
direction
0 Ω
No
Continuity
No
Continuity
0 V
Approx
15 VDC
CAUSE
Defective
high voltage
transformer
Defective
high voltage
rectifier
Defective
magnetron
Defective
magnetron
Defective
high voltage
transformer
Defective
high voltage
transformer
Defective
touch control
circuit
Faulty
contacts or
RELAY
(RY1) or open
relay coil
REMEDY
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
No microwave
oscillation
Check continuity of high
voltage rectifier in
forward and backward
direction with DC
megger
Check continuity of high
voltage capacitor
terminals with wires
removed
Connect megger leads to
magnetron terminal and
magnetron body
Check resistance of
primary and secondary
coil of high voltage
transformer
Check continuity of
magnetron with wires
removed
Check continuity of
filament terminal of high
voltage transformer
Check D.C. voltage
being supplied to
RELAY (RY1) coil
Continuity
Check continuity of high
voltage fuse
No Continuity
Replace high voltage fuse
or oo