LG 42PQ30 Training Manual page 39

Switch Mode Power Supply Static Test
Switch Mode Power Supply Static Test
This test can confirm the proper operation of the SMPS without the need to exchange the board.
This Power Supply can operate in a No Load State. This means that by applying AC power to
SC101 and all other plugs disconnected, this power supply will function.
Simply removing P813 (Lower Right Hand Side of the PWB), will cause the "AUTO" Pin 22 to go
high from its normal low state allowing the Power Supply to go to full power on mode when
AC Power is Supplied.
discharged before reconnecting the supply cables.
For a "Stand-Alone" static test for the Power Supply, apply the usual 2 100Watt light Bulbs in series
test between Vs output and chassis ground for a simulated 200Watt load. If the Power Supply
operates in this condition, it is assured it can maintain its output power under load.
If the Y-SUS, Z-SUS and X PWBs are working normal, when the SMPS comes up to full power on,
"Display Panel Reset" will be visible. Shorting the Auto Pattern Gen. test points at this time should
result with test patterns on the screen.
If either Y-SUS or Z-SUS is causing the power supply to shutdown, unplug the Z-SUS.
(Remember, Vs is routed to the Z-SUS PWB P3 from the Y-SUS P206 pins 1 & 2.
This will allow the Y-SUS to function. Also, if you unplug the Y-SUS from the SMPS and
jump the 5V VCC line to any 5V location on the Control Board the Control PWB will function.
Be careful after this test and make sure the VA and VS lines have
Preliminary Information 42PQ30
39