LG MC-8082WRS Service Manual ▷ View online
5-15
CONDITION
CHECK
RESULT
CAUSE
REMEDY
1. Fuse blows.
Continuity.
No continuity.
Continuity.
Shorted contact at
the primary switch.
the primary switch.
Replace primary
and monitor
switches.
and monitor
switches.
No continuity.
Normal.
Defective high
voltage capacitor.
voltage capacitor.
Replace high
voltage capacitor.
voltage capacitor.
Fuse blows again
Defective high volt-
age transformer.
age transformer.
Replace high volt-
age transformer.
age transformer.
Malfunction of the
monitor switch.
monitor switch.
Replace primary
and monitor
switches.
and monitor
switches.
Check continuity
of monitor
switch (with
door closed).
of monitor
switch (with
door closed).
Check continuity
of primary
switch (with
door opened).
of primary
switch (with
door opened).
Disconnect one
side of the wire
lead connected
from transformer
to the high
voltage
capacitor and
operate the unit.
side of the wire
lead connected
from transformer
to the high
voltage
capacitor and
operate the unit.
Replace fuse
(TROUBLE 2) Oven does not operate at all ; Display window does not display any figures and
no input is accepted.
NOTE : All these switches must be replaced at the same time. Refer to page 5-6, 5-7
2. Fuse does not
blow.
No continuity.
No continuity.
Replace power
supply cord.
supply cord.
Defective mag-
netron thermostat.
netron thermostat.
Defective power
supply cord.
supply cord.
Replace mag-
netron thermostat.
netron thermostat.
Check continuity
of magnetron
thermostat.
of magnetron
thermostat.
Check continuity
of power supply
cord.
of power supply
cord.
Continuity.
5-16
(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 little heat is produced in oven load.
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 fan
motor.
motor.
Replace fan
motor.
motor.
Replace fan
motor.
motor.
Loose connection.
Connection then
tightly.
tightly.
CONDITION
CHECK
RESULT
CAUSE
REMEDY
Output is low.
Lower than 90% of
rating voltage.
rating voltage.
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: Simple test of power output-conducted by heating one liter water for one min. if available.
5-17
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.
(TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run
(Display operates properly)
5-18
(TROUBLE 7) Grill
CONDITION
CHECK
RESULT
CAUSE
REMEDY
1. Heater is not
operating.
Abnormal.
Normal.
Normal.
Heater.
Thermostat and
relay3.(Grill)
relay3.(Grill)
Abnormal.
Malfunction the
thermostat.
thermostat.
Malfunction the
heater.
heater.
Replace.
Wire connection.
No continuity.
Open or loosen.
Replace or
connect tightly.
connect tightly.
Replace.
1. Lower tempera-
ture the oven.
Abnormal.
Normal.
Heater.
Thermostat and
relay3.(Grill)
relay3.(Grill)
Abnormal.
Malfunction the
thermostat.
thermostat.
Malfunction the
heater.
heater.
Replace.
Replace.
(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.
NOTE: * Make sure the wore leads correct position.
* When removing the wire leads from parts be sure to grasp the connector not the wires.
* When removing the magnetron, be sure to install the magnetron gasket in the correct position and in
* When removing the magnetron, be sure to install the magnetron gasket in the correct position and in
good condition.
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