LG LMH1017CVW Service Manual page 27

(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 operating 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˚C temperature rise is normal condition.
CHECK
Check continuity
of secondary
switch (with
door closed).
Check the con-
nection between
CN1 connector
and P.C.B
assembly.
Check fan motor.
Check oven lamp.
Check continuity
of primary switch.
CHECK
Check the
power source
voltage.
Disconnect the
wire leads from
relay 2 and
check on and off
time with
multitester.
Measure the
output power.
RESULT
No continuity.
Continuity.
Continuity
No continuity
Abnormal.
Abnormal.
Normal.
No continuity
Continuity
RESULT
Lower than 90% of
rating voltage.
Normal.
Abnormal.
Normal.
Abnormal.
5-16
CAUSE
Defective
secondary switch.
Defective P.C.B
assembly.
Loose connection.
Defective fan motor.
Defective oven lamp.
Defective primary switch.
CAUSE
Decrease in power
source voltage with
load.
Defective P.C.B
assembly.
Defective
magnetron.
REMEDY
Replace
secondary switch.
Replace P.C.B
assembly.
Connect them
tightly.
Replace fan motor.
Replace oven lamp.
Replace primary switch.
REMEDY
Suggest customer
contact local electric
power utility co. or
qualified electrician.
Replace P.C.B
assembly.
Replace
magnetron.