LG 42PQ20 Training Manual page 82

Circuit Interconnect Blowup Control Board Section
Circuit Interconnect Blowup Control Board Section
Note: Pins 9 & 10 of connector P813 on the SMPS, if the
supply is working, should have 5V which under normal
operation supplies the Control Board with 5V via the Y SUS Board.
By using 5V STB, the following test will confirm Normal operation of
the Control Board if that supply is missing.
82 January 2009 Plasma 42PQ20