Panasonic NN-ST250W / NN-ST250M / NN-ST250WZPE / NN-ST250MZPE Service Manual ▷ View online
5-15
(TROUBLE 3) Display shows all figures set, but oven does not start cooking while
desired program times are set and START pad is touched.
(TROUBLE 4) Oven seems to be operation but output power is low.
CONDITION
CHECK
RESULT
CAUSE
REMEDY
1.Setting time does
not count down
when touching
START pad.
when touching
START pad.
2. Fan motor or
oven lamp
do not turn
on.
do not turn
on.
No continuity.
continuity.
No continuity.
Continuity.
Check the con-
nection between
connector and
P.C.B assembly.
nection between
connector and
P.C.B assembly.
Defective
secondary switch.
secondary switch.
Replace
secondary switch.
secondary switch.
Defective P.C.B
assembly.
assembly.
Replace P.C.B
assembly.
assembly.
Check continuity
of secondary
switch (with
door closed).
of secondary
switch (with
door closed).
Check fan motor.
Check oven lamp.
Abnormal.
Abnormal.
Normal.
Defective fan
motor.
motor.
Defective oven
lamp.
lamp.
Replace fan
motor.
motor.
Replace oven
lamp.
lamp.
Loose connection.
Connection then
tightly.
tightly.
CONDITION
CHECK
RESULT
CAUSE
REMEDY
Output is low.
Lower than 90% of
rating voltage.
rating voltage.
Normal.
Normal.
Abnormal.
Abnormal.
Measure the
output power.
output power.
Disconnect the
wire leads from
relay 2 and check
on and off time
with multitester.
wire leads from
relay 2 and check
on and off time
with multitester.
Defective P.C.B
assembly.
assembly.
Replace P.C.B
assembly.
assembly.
Decrease in power
source voltage
with load.
source voltage
with load.
Suggest customer
contact local
electric power
utility co. or
qualified
electrician.
contact local
electric power
utility co. or
qualified
electrician.
Check the
power source
voltage.
power source
voltage.
Defective
magnetron.
magnetron.
Replace
magnetron.
magnetron.
NOTE: Refer to Page 5-3 for measuring of microwave power output.
5-16
CONDITION
CHECK
RESULT
CAUSE
REMEDY
No microwave
oscillation.
oscillation.
No continuity.
Continuity.
Defective P.C.B
assembly
assembly
Replace P.C.B
assembly
assembly
Disconnect the
wire leads from
relay 2 and
check continuity
of relay2.
(Operate the
unit)
wire leads from
relay 2 and
check continuity
of relay2.
(Operate the
unit)
Abnormal
normal
Defective high
voltage
transformer.
voltage
transformer.
Replace high
voltage
transformer .
voltage
transformer .
Check H.V.
transformer.
transformer.
normal
normal
Abnormal
Defective high
voltage Diode.
voltage Diode.
Replace high
voltage Diode.
voltage Diode.
Check H.V.
diode.
diode.
Abnormal
Defective high
voltage capacitor.
voltage capacitor.
Replace high
voltage capacitor.
voltage capacitor.
Check H.V.
capacitor.
capacitor.
Abnormal
Defective
magnetron.
magnetron.
Replace
magnetron .
magnetron .
Check
Magnetron.
Magnetron.
normal
Abnormal
Defective
Protector Diode.
Protector Diode.
Replace
Protector Diode .
Protector Diode .
Check
Protector Diode.
Protector Diode.
(TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run
(Display operates properly)
5-17
(TROUBLE 6) Oven does not cook properly when programmed for the set power level
(Operates properly on HIGH)
CONDITION
CHECK
RESULT
CAUSE
REMEDY
Output is full when
you set lower
power level.
power level.
Abnormal.
Disconnect the
wire leads from
relay 2 and check
continuity relay 2.
(Operate the unit)
wire leads from
relay 2 and check
continuity relay 2.
(Operate the unit)
Defective P.C.B.
assembly.
assembly.
Replace P.C.B.
assembly.
assembly.
OVEN CAVITY PARTS
INTERIOR PARTS
BASE PLATE PARTS
LATCH BOARD PARTS
CONTROL PANEL PARTS
DOOR PARTS
6-1
EXPLODED VIEW
INTRODUCTION
Click on the first or last page to see other NN-ST250W / NN-ST250M / NN-ST250WZPE / NN-ST250MZPE service manuals if exist.