LG MB-387W Service Manual - Page 24

CONDITION, CHECK, RESULT, CAUSE, REMEDY, TROUBLE 2, Oven does not operate at all ; Display window

Page 24 highlights

(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). RESULT Continuity. No continuity. Continuity. No continuity. CAUSE Malfunction of the monitor switch. REMEDY Replace primary and monitor switches. Shorted contact at the primary switch. Replace primary and monitor switches. Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit. Normal. Fuse blows again Defective high voltage capacitor. Defective high voltage transformer. Replace high voltage capacitor. Replace high voltage transformer. NOTE : All these switches must be replaced at the same time. Refer to page 5-6, 5-7 2. Fuse does not blow. Check continuity of magnetron thermostat. No continuity. Continuity. Check continuity of power supply cord. No continuity. Defective magnetron thermostat. Replace magnetron thermostat. Defective power supply cord. Replace power supply cord. 5-14

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5-14
CONDITION
CHECK
RESULT
CAUSE
REMEDY
1. Fuse blows.
Continuity.
No continuity.
Continuity.
Shorted contact at
the primary switch.
Replace primary
and monitor
switches.
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 primary
and monitor
switches.
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
(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.
Defective mag-
netron thermostat.
Defective power
supply cord.
Replace mag-
netron thermostat.
Check continuity
of magnetron
thermostat.
Check continuity
of power supply
cord.
Continuity.