LG RH7521W Service Manual page 72

Sled operating is abnormal
Is there sled
control signal output?
(LIC301 pin 126, 127)
YES
Is there
sled drive signal input?
(LIC502 pin 29, 30)
YES
Is there
sled drive voltage output?
(LIC502 pin 37~40)
YES
Is there
sled drive voltage output?
(LCN501 pin 1,2,3,4)
NO
Check the connection LCN501.
NO
Replace the LIC301
•Replace the IC102.
NO
•Check the LR532, LR533.
Is DRV-CTRL1
NO
(LIC502 pin35)
Replace the LIC502
YES
Replace the sled motor.
signal "H"?
YES