LG MC-804AR Service Manual ▷ View online
5-15
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
keys.
pressing other than touch
keys.
Defective tact switch 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 tact switch key of
P.C.B.
P.C.B.
Test procedure tact switch
key of P.C.B.
key of P.C.B.
Test procedure secondary
switch.
switch.
Test procedure tact switch
key of P.C.B.
key of P.C.B.
CAUSE
TEST PROCEDURE OR
CORRECTION
Incorrect touch key.
Touch key again after
closing.
closing.
Loose connection.
Test tact switch key of
P.C.B.
P.C.B.
(TROUBLE 2) Oven does not at all even thought MOTOR and P.C.B program.
5-16
CONDITION
Oven does not go into a
cook cycle when START key
is touched.
cook cycle when START key
is touched.
Primary and secondary
interlock switches defective
or out of adjustment.
interlock switches defective
or out of adjustment.
Defective flat cable of
P.C.B.
P.C.B.
Test procedure flat cable of
P.C.B.
P.C.B.
Test procedure primary and
secondary switches.
secondary switches.
CAUSE
TEST PROCEDURE OR
CORRECTION
Defective tact switch key of
P.C.B.
P.C.B.
Test procedure tact switch
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.
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 food.
oven edges of turntable prevents
turning rearrange food.
1. Wrap the thinner part with
aluminum foil.
2. Use plastic wrap or with a lid.
3. Stir once or twice while cooking
3. Stir once or twice while cooking
soup, cocoa or milk etc.
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 2 of P.C.B.
High AC input voltage.
Use the microwave oven at
adequate line voltage.
adequate line voltage.
Test procedure relay 2 of
P.C.B.
P.C.B.
(TROUBLE 3) Oven does not operating microwave cooking
5-17
CONDITION
No microwave oscillation.
Defective relay 2 of P.C.B.
Defective high voltage
transformer.
transformer.
Test procedure high voltage
transformer.
transformer.
Test procedure relay 2 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 fuse
Check and repair wiring.
Check fuse
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
5-18
CONDITION
Convection indicator lights
but oven does not go into
cook cycle when START key
is touched.
but oven does not go into
cook cycle when START key
is touched.
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.
Defective Relay 4, 8.
Defective relay 3, 4 or relay
8.
8.
Defective convection heater
element.
element.
Defective grill heater
element.
element.
Defective circulation Motor.
Defective or disconnected
thermistor.
thermistor.
Defective Solenoid
Defective Rectifire ASM
Defective DAMPER of
Airduct
Airduct
Defective thermistor.
Test procedure thermistor.
Check and repair C-Motor wire
ass'y. (COM:YL, 24V:BN, 230V:BL)
ass'y. (COM:YL, 24V:BN, 230V:BL)
Check and replace
C-Motor.
C-Motor.
Test procedure relay 4, 8 of
P.C.B.
P.C.B.
Test procedure relay 3, 4 or
relay 8 of P.C.B.
relay 8 of P.C.B.
Test procedure convection
heater.
heater.
Test procedure grill heater.
Check the rotating of
circulation fan.
circulation fan.
Test or replace thermistor.
Test or Replace Solenoid
Check Diode(4pcs) or
Replace Rectifire ASM
Replace Rectifire ASM
Check or Repair Damper
Pin and spring.
Pin and spring.
CAUSE
TEST PROCEDURE OR
CORRECTION
(TROUBLE 4) Oven does not operate convection cooking
F1, F2, F5 is Fail display
Thermistor short (F1)
No sensing of
thermistor (F2)
thermistor (F2)
High initial temperature of
oven cavity. (F5)
oven cavity. (F5)
Replace thermistor
Wait until low temperature of
oven cavity.
oven cavity.
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