LG LMC1575BD Service Manual page 27

(TROUBLE 2) Oven does not operate at all, Display window does not display any figures, and no input is accepted.
CONDITION
1. Fuse blows.
CHECK
Check continuity of
monitor switch (with
door closed).
Replace fuse
Check continuity of
primary switch (with
door opened).
Check continuity of
secondary switch (with
door opened).
check inverter
(refer page 5-15)
Check magnetron
RESULT
Continuity.
No continuity.
Continuity.
No continuity.
Continuity.
No continuity.
Abnormal
normal
Abnormal
5-15
CAUSE
Malfunction of the
monitor switch.
Shorted contact at the
primary switch.
Malfunction of secondary
switch.
Defect inverter
Defect magnetron
REMEDY
Replace fuse,
Latch board assembly
and main PCB
Replace fuse,
Latch board assembly
and main PCB
Replace fuse,
Latch board assembly
and main PCB
Replace inverter
Replace magnetron