LG MB-339MB, Service Manual

Page: 25 / 38

5-15
CONDITION CHECK RESULT CAUSE REMEDY
1. Fuse blows. Continuity.
No continuity.
Continuity.
Shorted contact at
the primary switch.
Replace fuse,
primary, monitor,
secondary
switches, and
RELAY(RY2) of
P.C.B Assembly.
No continuity.
Normal.
Defective high
voltage capacitor. Replace high
voltage capacitor.
Fuse blows again
Defective high volt-
age transformer. Replace high volt-
age transformer.
Malfunction of the
monitor switch. Replace fuse,
primary, monitor,
secondary
switches, and
RELAY(RY2) of
P.C.B Assembly.
Check continuity
of monitor
switch (with
door closed).
Check continuity
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.
Replace fuse
Continuity.
Malfunction of
secondary switch.
Replace fuse,
primary, monitor,
secondary
switches, and
RELAY(RY2) of
P.C.B Assembly.
No continuity.
Check continuity
of secondary
switch (with
door opened).
2. Fuse does not
blow.
No continuity.
Continuity.
No continuity.
Defective power
supply cord. Replace power
supply cord.
Defective
thermostat. Replace
thermostat. Check continuity
of thermostat.
Check continuity
of power supply
cord.
(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 5-7, 5-8