Daewoo KOC-972T0S, Service Manual, Page: 27 / 53

TROUBLE SHOOTING GUIDE
(TROUBLE 3) No microwave oscillation even though fan motor rotates.
CON DITION
CHECK RESULT
No
Continuity
Continuity
Continuity in
backw ard
direction
Continuity
0 or
Ω
No
Continuity
No
Continuity
0 V
Approx
12 VDC
CAUSE
Defective
high voltage
transform er
Defective
high voltage
rectifier
Defective
m agnetron
Defective
m agnetron
Defective
high voltage
transform er
Defective
high voltage
transform er
Defective
touch control
circuit
Faulty
contacts of
RELAY
(RY1) or open
relay coil
REM EDY
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
N o m icrowav e
oscillation
C heck con tinuity of high
voltage fuse
C heck con tinuity of high
voltage rectifier in
forw ard and backw ard
direction with D C
m egg er
C heck con tinuity of high
voltage capacitor
term inals w ith w ires
rem oved
C onnect m egger leads to
m agn etron term inal and
m agn etron body
C heck resis tance of
prim ary and secondary
coil of high voltage
transform er
C heck con tinuity of
m agn etron w ith w ires
rem oved
C heck con tinuity of
filam ent term inal of high
voltage transform er
C heck D .C. voltage
being supplied to
R ELAY (R Y1) coil
R eplace high voltage fuse