LG LMVM2277ST Service Manual page 28

(2)CHECKOUT PROCEDURES FOR RELAY.
-PROBLEM (A)-
FAN motor turns on without touching START key when
the door is closed.
NO
Remove the mate connector of I/O
GOOD
CON from the circuit board.
Does the unit still operate?
Replace the
circuit board
-PROBLEM (B)-
FAN motor turns on When the door is closed and
START key is touched.
YES
Measure the voltage at pin NO.
GOOD
1, 5 of CN1
Voltage reading:120 V AC
Replace the
circuit board
YES
NO
Defective
Wire Assembly
Replace
Wire Assembly
NO
NO
Defective
FAN motor
Replace
FAN motor.
Oven lamp turns on without touching START key when
NO
GOOD
YES
Oven lamp turns on When the door is closed and
YES
GOOD
YES
7-18
-PROBLEM (A)--
the door is closed.
YES
Remove the mate connector of I/O
CON from the circuit board.
Does the unit still operate?
NO
Replace the
circuit board
-PROBLEM (B)-
START key is touched.
NO
Measure the voltage at pin NO.
1, 7 of CN1
Voltage reading:120 V AC
NO
Replace the
circuit board
YES
Defective
Wire Assembly
Replace
Wire Assembly
YES
Defective
Oven lamp
Replace
Oven lamp