LG MS-285SD Service Manual ▷ View online
A. PRIMARY INTERLOCK SWITCH
TEST
When the door release button is depressed slowly
with the door closed, an audible click should be
heard at the same time or successively at intervals.
When the button is released slowly, the latches
should activate the switches with an audible click.
with the door closed, an audible click should be
heard at the same time or successively at intervals.
When the button is released slowly, the latches
should activate the switches with an audible click.
If the latches do not activate the switches when the
door is closed, the swithces should be a adjusted in
accordance with the adjustment procedure.
Disconnect the wire lead from the primary switch.
Connect the ohmmeter leads to the common (COM)
and normally open (NO) terminal of the switch. The
meter should indicate an open circuit in the door
open condition.
door is closed, the swithces should be a adjusted in
accordance with the adjustment procedure.
Disconnect the wire lead from the primary switch.
Connect the ohmmeter leads to the common (COM)
and normally open (NO) terminal of the switch. The
meter should indicate an open circuit in the door
open condition.
When the door is closed, the meter should indicate
a closed circuit.
a closed circuit.
When the primary switch operation is abnormal,
make the necessary adjustment or replace the
switch only with the same type of switch.
make the necessary adjustment or replace the
switch only with the same type of switch.
B. SECONDARY INTERLOCK SWITCH TEST
Disconnect the wire lead from the secondary switch.
Connect the ohmmeter leads to the common (COM)
and normally open (NO) terminals of the switch. The
meter should indicate a open circuit in the door
open condition. When the door is closed, meter
should indicate a closed circuit. When the sec-
ondary switch operation is abnormal, make the nec-
essary adjustment or replace the switch only with
the same type of switch.
Connect the ohmmeter leads to the common (COM)
and normally open (NO) terminals of the switch. The
meter should indicate a open circuit in the door
open condition. When the door is closed, meter
should indicate a closed circuit. When the sec-
ondary switch operation is abnormal, make the nec-
essary adjustment or replace the switch only with
the same type of switch.
C. MONITOR SWITCH TEST
Disconnect the wire lead from the monitor switch.
Connect the ohmmeter leads to the common (COM)
and normally closed (NO) terminals of the switch.
The meter should indicate closed circuit in the door
open condition. When the door is closed, meter
should indicate an open circuit. When the monitor
switch operation is abnormal, replace with the same
type of switch.
NOTE: After repairing the door or the interlock
system, it is necessary to do this continuity test
before operating the oven.
Connect the ohmmeter leads to the common (COM)
and normally closed (NO) terminals of the switch.
The meter should indicate closed circuit in the door
open condition. When the door is closed, meter
should indicate an open circuit. When the monitor
switch operation is abnormal, replace with the same
type of switch.
NOTE: After repairing the door or the interlock
system, it is necessary to do this continuity test
before operating the oven.
Interlock continuity Test
5-8
WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION
EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY SWITCH
TYPE NO. SZM-V 16-FA-61 OR VP-531A-OF FOR MONITOR SWITCH
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH
TYPE NO. SZM-V 16-FA-61 OR VP-531A-OF FOR MONITOR SWITCH
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH
COMPONENTS
TEST PROCEDURE
RESULTS
SWITCHES
Check for continuity of the switch
(Wire leads removed)
with an Ohm-meter
Primary
Switch
Switch
Monitor
Switch
Switch
Secondary
Switch
Switch
NOTE: After checking for the continuity of switches, make sure that are
connected correctly.
Door
open
open
Door
close
close
COM
NO
COM
NC
COM
NO
COM
NO
Component Test Procedure
5-9
CAUTIONS
1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUT
CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF
WATER IN CONTAINER) IN THE OVEN.
COMPONENTS
TEST PROCEDURE
RESULTS
HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)
1. Measure the resistance.
(Multi-meter scale: R 5 1 and R 5 100)
●
Primary winding
Approx: 2
Ω
●
Secondary winding
Approx: 125
Ω
●
Filament winding
Less than: 1
Ω
2. Measure the resistance.
(Multi-meter scale: R 5 1000)
●
Primary winding to ground
Normal:
∞
.
●
Filament winding to ground
Normal:
∞
.
MAGNETRON
1. Measure the resistance.
(Wire leads removed)
(Multi-meter scale: R 5 1)
●
Between filament terminals
Normal: Less than 1
Ω
2. Measure the resistance.
(Multi-meter scale: R 5 1000)
●
Filament to chassis.
Normal:
∞
.
Filament
Winding
Terminal
Winding
Terminal
Filament
Winding
Terminal
Winding
Terminal
Secondary
Winding
Winding
Primary
Winding
Winding
Component Test Procedure
5-9
CAUTIONS
1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUT
CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF
WATER IN CONTAINER) IN THE OVEN.
COMPONENTS
TEST PROCEDURE
RESULTS
HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)
1. Measure the resistance.
(Multi-meter scale: R 5 1 and R 5 100)
●
Primary winding
Approx: 2
Ω
●
Secondary winding
Approx: 125
Ω
●
Filament winding
Less than: 1
Ω
2. Measure the resistance.
(Multi-meter scale: R 5 1000)
●
Primary winding to ground
Normal:
∞
.
●
Filament winding to ground
Normal:
∞
.
MAGNETRON
1. Measure the resistance.
(Wire leads removed)
(Multi-meter scale: R 5 1)
●
Between filament terminals
Normal: Less than 1
Ω
2. Measure the resistance.
(Multi-meter scale: R 5 1000)
●
Filament to chassis.
Normal:
∞
.
Filament
Winding
Terminal
Winding
Terminal
Filament
Winding
Terminal
Winding
Terminal
Secondary
Winding
Winding
Primary
Winding
Winding
Component Test Procedure
5-9
CAUTIONS
1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUT
CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF
WATER IN CONTAINER) IN THE OVEN.
COMPONENTS
TEST PROCEDURE
RESULTS
HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)
1. Measure the resistance.
(Multi-meter scale: R 5 1 and R 5 100)
●
Primary winding
Approx: 2
Ω
●
Secondary winding
Approx: 125
Ω
●
Filament winding
Less than: 1
Ω
2. Measure the resistance.
(Multi-meter scale: R 5 1000)
●
Primary winding to ground
Normal:
∞
.
●
Filament winding to ground
Normal:
∞
.
MAGNETRON
1. Measure the resistance.
(Wire leads removed)
(Multi-meter scale: R 5 1)
●
Between filament terminals
Normal: Less than 1
Ω
2. Measure the resistance.
(Multi-meter scale: R 5 1000)
●
Filament to chassis.
Normal:
∞
.
Filament
Winding
Terminal
Winding
Terminal
Filament
Winding
Terminal
Winding
Terminal
Secondary
Winding
Winding
Primary
Winding
Winding