LG MB-4342A Service Manual page 21

COMPONENTS
Disconnect the 8 pin
connector from P.C.B.
(Refer to schemetic diagram
on page 4-3)
RELAY 2, RELAY 3
OF P.C.B.
(Wire leads removed.)
Note: Relay
Relay 1: Fan motor
Turntable motor
Oven lamp
Relay 2: Microwave
Relay 3: Grill
FAN MOTOR
(Wire leads removed)
TURNTABLE
MOTOR
(Wire leads removed)
NOTE : • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON.
• MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION.
• WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE
CONNECTOR, NOT THE WIRES.
TEST PROCEDURE
1 3 5 7 8
Relay 3
Relay 2
Measure the resistance.
(Ohm-meter scale: R x 1)
A
B
C
Measure the resistance.
(Ohm-meter scale: R x 1000)
5-11
RESULTS
Cooking Start OFF
Cooking Start OFF
Normal:
A ~ B A ~ C
30 ~ 50Ω 300~500Ω
Abnormal: ∞ or several Ω
Normal: Approx. 100~200 Ω
Abnormal: ∞ or several Ω