Power supply output voltage

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Check the various voltages coming from the power supply board and see if they are all ok, there is a legend on the power supply board to show what voltages are at what pins on the connectors,the 5 volt standby we know is good as long as the set has sound, but check the others

LG 47LN5400 no backlight repair Part 1
Have you tried some Youtube suggestions about this model ? LG is a special brand most difficult to do something without an service manual , control for bad solderings (special on active components with heatsinks) , bad fitted fcc sheets connectors power supply In safety mode because of an failure somwhere.

This is a common problem for LG 42LN5xxx & 47LN5xxx LED TVs, the problem is defective LED back lights strips, it has nothing to do with main power supply & the main board.

You need to use a ESR meter to check capacitors

tried to disconnected the 24v supply connectors going to the power inverter board which may the cause of voltage drop. after you disconnect then if still no output 24v dc coming from the power supply board the cause will be bad power supply board. check for an open resistance or bad regulators going to the 24vdc out. by the way you should connect all the connectors going to the main board to turn on the processor and the inv_on voltage going to the inverter board.

tried first to disconnect the supply connector going to the inverter board for back light just to ensure if their is no shorted component here. and then turn the power on again if the light stay then the inverter board was the cause why won't power on. by the way did you make a voltage checking at the power supply board does it have correct output voltages 5v,12-16v and the 24v.

First, inspect the electrolytic capacitors on the power supply board. The top of a burned-out capacitor is often domed instead of flat. You may measure proper voltage with no load, but the bad capacitor will not support a load. (Note: the voltages are usually printed on the board next to the output connector.) The page linked below includes a nice illustration of both good and bad capacitors. Also, check the LED driver board for the same problem. If you don't see anything like that, add a comment to the post to that effect, and we'll look at other possibilities.

CapacitorLCDPARTS net

I'd try the main, its about all that is left if the rails are all good on the power board.

Good day!!!!

I need to know if the LED lights ON or blinking if that so how many blinks?

If you have multimeter kindly try this procedure:

1. Open the back cover.
2. Look at the power supply board.(it is usually connected directly to the power cord)
3. Get your multimeter (range in DC).
4. measure all output to the power supply such as 5vdc,3.3vdc,12vdc,etc..It is usually indicated on the power supply output connector.
5. Place your black test probe to the ground and the red one is for the positive voltage as stated above and also measure VS and VA voltage..

Then let me know what are the readings of all voltages together with the original voltage marked on those voltages..