Switch Mode Power Supply Static Test - LG 50PG20 Training Manual

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
CN101 and all other plugs disconnected, this power supply will function.
Simply removing P803 (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. Be careful after this test and make sure the VA and VS lines have
discharged before reconnecting the supply cables.
If either Y-SUS or Z-SUS is causing the power supply to shutdown, unplug the Z-SUS.
This will allow the Y-SUS to function. If you unplug the Y-SUS from the SMPS, and
jump the 5V VCC line to the Y- SUS for Control Board Power the Z-SUS will function.
If the Y-SUS and Z-SUS 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 not check for 16V and VA to the X Boards).
For a "Stand-Alone" static test for the Power Supply, apply the usual 2 100Watt light Bulbs test on
the Vs output line for a simulated load. If the Power Supply operates in this condition, it is
assured it can maintain its output power under load.
Plasma Spring 2009
41
50PG20