Daewoo KOR-137B Service Manual page 19

(TROUBLE 3) No microwave oscillation even though fan motor rotates.
CONDITION
No
microwave
oscillation
Check continuity of high voltage
rectifier in forward and backward
Check resistance of primary and
CHECK
Check continuity of high
voltage capacitor terminals
with wires removed
direction with DC megger
Connect megger leads to
magnetron terminal and
magnetron body
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
RESULT
Continuity
Defective high
transformer
Continuity in
Defective high
backward
voltage rectifier
direction
Continuity
0 Ω or ∞
Defective high
transformer
No
Continuity
No
Defective high
Continuity
transformer
0 V
Defective touch
control circuit
Approx
15 VDC
RELAY (RY1)
18
CAUSE REMEDY
Replace
voltage
Replace
Replace
Defective
magnetron
Replace
voltage
Replace
Defective
magnetron
Replace
voltage
Replace
Replace
Faulty
contacts or
or open
relay coil