LG 42LH20 - Test 2: Backlight Test

February 2009 42LH20
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Continue if the 1
st
test was successful. Leave original 10K resistor in
place.
(3) Add another 10K resistor between (5V) pin 7, 8, 9 or 10 and
Pin 20 (INV On).
(4) Apply AC Power. This simulates a Power On and Backlight On command.
Observe the Backlights.
a) If normal, the backlights should turn on.
b) If the do not, recheck connectors P401 and P401.
(Warning: Disconnect the AC Power first).
These pins carry 1.2Kv when active.
c) Confirm the INV On/Off line Pin 12 is going to at least 3V.
d) If no backlight activity, SMPS is defective.
TEST 2 Power Supply PWB Backlights Test
TEST 2 Power Supply PWB Backlights Test
P700 Connector disconnected from the Main PWB.
Apply AC after adding jumpers.
Use P700
Side to insert
resistors