19
 
(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
REMEDY
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
Replace
Check resistance of primary and 
secondary coil of high voltage 
transformer
0 Ω or ∞
Defective high 
voltage 
transformer
Replace
Check continuity of magnetron 
with wires removed
No
Continuity
Defective 
magnetron
Replace
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
15 VDC
Faulty
contacts or 
RELAY (RY1)
or open
relay coil
Replace