Daewoo KOC-9N2T7S, Service Manual, Page: 23 / 45

22
TROUBLE 3) No microwave oscillation even though fan motor rotates.
CONDITION CHECK RESULT
Check continuity of
high voltage capacitor terminals
with wires removed
Continuity
CAUSE
Defective
high voltage
transformer
Defective
high voltage
fuse
REMEDY
1
Replace
No
microwave
oscillation
Check continuity of
high voltage rectifier in forward
and backward
direction with DC megger
Continuity
in backward
direction
Defective high
voltage rectifier
Replace
Connect megger leads to
magnetron terminal and
magnetron body
Continuity
Defective
magnetron
2
1
Check resistance of primary
and secondary coil of high
voltage transformer
0 or
Defective
high voltage
transformer
Replace
Check continuity of
high voltage fuse
No microwave oscillation
No
continuity
2
Check continuity of
magnetron heater with wires
removed
No continuity
Defective
magnetron
Replace
1
Check continuity of filament
terminal of high voltage
transformer
No continuity
Defective high
voltage
transformer
Replace
Check D.C voltage
being supplied to
RELAY (RY1) coil
0 V
Defective
touch control
circuit
Replace
Approx.
24V DC
Faulty contacts of
RELAY
(RY1) or open
relay coil
Replace