LG 42LH90 Manual page 36

Power Supply Board Low Voltage Test 1
Power Supply Board Low Voltage Test 1
AC Should not be applied at any time while adding resistors or while
unplugging connectors as damage to the circuit Board may occur.
a) When AC is applied, the SMPS "MUST" be producing STBY 5V on
pins 7, 8, 9 or 10 of P201.
If 5V Standby is not being generated, the SMPS is defective and
must be replaced. There is no need to continue with the next test.
But, make sure the Main Power Switch is On.
(b) Unplug P700 on the Main Board to make insertion of the Resistors much
easier.
TEST 1:
(1) Add a 100Ω resistor between (5V STBY) pin 7, 8, 9 or 10 and Pin 2
(PWR). Apply AC. This will turn on the power supply.
a) Check that the 24V and 12V power supplies are
turned on,
•
P201 (24V pins 17 and 18)
•
P201 (12V pins 13 and 14)
•
P203 (24V pins 1 through 5) to the Inverter.
(2) Remove AC power.
No Backlights during this test
36 February 2010
Use P700
Side to insert
resistors
LCD DV 42LH90