LG MC-783RC Service Manual ▷ View online
24
CONDITION
No input can be
programmed.
programmed.
Some inputs can not be
programmed.
programmed.
Display fixes some figure and
can not accept any input.
can not accept any input.
Set time does not count
down when touched START.
down when touched START.
Display shows a number or
figure different from one
touched.
figure different from one
touched.
Random programming when
pressing other than touch
pads.
pressing other than touch
pads.
Defective membrane key of
P.C.B.
P.C.B.
Loose connection.
Connect them tightly.
Defective secondary switch
or out of adjustment
or out of adjustment
Defective membrane key of
P.C.B.
P.C.B.
Test procedure membrane
key of P.C.B.
key of P.C.B.
Test procedure secondary
switch.
switch.
Test procedure membrance
key of P.C.B.
key of P.C.B.
CAUSE
TEST PROCEDURE OR
CORRECTION
Incorrect touch pad.
Touch pad again after
closing.
closing.
Loose connection.
Test membrance key of
P.C.B.
P.C.B.
(TROUBLE 2) Oven does not at all even thought MOTOR and P.C.B program.
25
CONDITION
Oven does not go into a
cook cycle when START
pad is touched.
cook cycle when START
pad is touched.
Primary and secondary
interlock switches defective
or out of adjustment.
interlock switches defective
or out of adjustment.
Defective relay 1 of P.C.B.
Test procedure relay 1 of
P.C.B.
P.C.B.
Test procedure primary and
secondary switches.
secondary switches.
CAUSE
TEST PROCEDURE OR
CORRECTION
Defective membrane key of
P.C.B.
P.C.B.
Test procedure membrane
key of P.C.B.
key of P.C.B.
Open or loose wiring to
above components.
above components.
Check and repair wiring.
Ouput power is too low.
Defective fan motor.
Low AC input voltage.
Use the microwave oven at
adequate line voltage.
adequate line voltage.
Test procedure fan motor.
Food temperature is too low.
This may not be a defect.
It is possible that the food
should be cooked for a
longer period.
It is possible that the food
should be cooked for a
longer period.
Defective relay 3 of P.C.B.
Test procedure relay 3 of
P.C.B.
P.C.B.
Uneven cooking.
Inconsistent intensity of
microwave by their
characteristics.
microwave by their
characteristics.
Food does not turn during
cook cycle.
cook cycle.
Food or cookware extending
oven edges of turntable
prevents turning rearrange
oven edges of turntable
prevents turning rearrange
1. Wrap the thinner part with
aluminum foil.
2. Use plastic wrap or with a lid.
3. Stir once or twice while
3. Stir once or twice while
cooking soup, cocoa or milk
Turntable motor does not
operate.
operate.
Refer to preceding turntable
motor problem.
motor problem.
Output is too high when you
set lower power level.
set lower power level.
Defective relay 1 of P.C.B.
High AC input voltage.
Use the microwave oven at
adequate line voltage.
adequate line voltage.
Test procedure relay 1 of
P.C.B.
P.C.B.
(TROUBLE 3) Oven does not operating microwave cooking
26
CONDITION
No microwave oscillation.
Defective relay 1 of P.C.B.
Defective high voltage
transformer.
transformer.
Test procedure high voltage
transformer.
transformer.
Test procedure relay 1 of
P.C.B.
P.C.B.
CAUSE
TEST PROCEDURE OR
CORRECTION
Defective high voltage
capacitor.
capacitor.
Defective high voltage
diode.
diode.
Test procedure high voltage
diode.
diode.
Test procedure high voltage
capacitor.
capacitor.
Defective magnetron.
Low AC input voltage.
Use the microwave oven at
adequate line voltage.
adequate line voltage.
Test procedure magnetron.
Open or loose wiring to
above components.
above components.
Blown H.V. Fuse
Check H.V. Fuse
Check and repair wiring.
Spark occurring.
Using metallic ware and
allowing it to touch the
oven wall.
allowing it to touch the
oven wall.
Ceramic ware trimmed in
gold or silver powder is used.
gold or silver powder is used.
Do not use any type of cook
ware with metallic trimming.
ware with metallic trimming.
Do not use metallic ware for
cooking except where noted
in the cookbook.
cooking except where noted
in the cookbook.
Grill rack is using in no load
condition.
condition.
Do not use the oven at
microwave and combination
mode with the grill rack
placed in the cavity when
the oven is empty.
microwave and combination
mode with the grill rack
placed in the cavity when
the oven is empty.
(TROUBLE 3) Oven does not operating microwave cooking
27
CONDITION
Convection indicator lights
but oven does not go into
cook cycle when START
pad is touched.
but oven does not go into
cook cycle when START
pad is touched.
F1, F2, F3 is fail display
Temperature in the oven
cavity is lower or higher than
preset.
cavity is lower or higher than
preset.
Defective circulation motor
wire ass'y.
wire ass'y.
Defective circulation
MOTOR.
MOTOR.
Check and replace
C-Motor.
C-Motor.
Check and repair
C-Motor wire ass'y.
C-Motor wire ass'y.
CAUSE
TEST PROCEDURE OR
CORRECTION
Defective thermistor.
Defective Relay 2, 4, 5.
Thermistor short(F1)
No sensing of thermistor(F2)
Key switch short(F3)
Test procedure relay 2,
4, 5 of P.C.B.
4, 5 of P.C.B.
Replace thermistor
Repair key switch
Test procedure thermistor.
Defective relay 2 or relay 5.
Defective convection heater
element.
element.
Test procedure convection
heater.
heater.
Test procedure relay 2 or
relay 5 of P.C.B.
relay 5 of P.C.B.
Defective grill heater
element.
element.
Defective circulation Motor.
Check the rotating of
circulation fan.
circulation fan.
Test procedure grill heater.
Defective or disconnected
thermistor.
thermistor.
Defective Solenoid
Defective Rectifire ASM
Defective Damper of Air
Duct
Duct
Test or replace thermistor.
Test or Replace Solenoid
Check diode(4pcs) or
Replace Rectifire ASM
Replace Rectifire ASM
Cheek or repair damper pin
and spring
and spring
(TROUBLE 4) Oven does not operate convection cooking
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