LG MS-1146SQP Service Manual page 24

(TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired
program times are set and START pad is touched.
CONDITION
1.Setting time
does not count
down when
touching START
pad.
2. Fan motor or
oven lamp do
not turn on.
(TROUBLE 4) Oven seems to be operation but little heat is produced in oven load.
CONDITION
Output is low.
NOTE: Simple test of power output-conducted by heating one liter water for one min. if available.
Minimum 8.5 o C temperature rise is normal condition.
CHECK
Check continuity
No continuity.
of secondary
switch (with
door closed).
Continuity.
Check the con-
Continuity
nection between
CN1 connector
and PCB
No continuity
assembly.
Check fan motor. Abnormal
Check oven lamp. Abnormal
Normal
CHECK
Lower than 90% of
Check the
rating voltage.
power source
voltage.
Normal.
Disconnect the
Abnormal.
wire leads from
relay 2 and
check on and off
Normal.
time with
multitester.
Measure the
Abnormal.
output power.
RESULT
Defective
secondary switch.
Defective PCB
assembly.
Loose connection.
Defective fan motor.
Defective oven lamp.
RESULT
Decrease in power
source voltage
with load.
Defective PCB
assembly.
Defective
magnetron.
5-14
CAUSE REMEDY
Replace
secondary switch.
Replace PCB
assembly.
Connection then
tightly.
Replace fan motor.
Defective oven lamp.
CAUSE REMEDY
Suggest customer
contact local
electric power
utility co. or
qualified
electrician.
Replace PCB
assembly.
Replace
magnetron.