lg 47le5400 powers up, black screen, no sound

[budm]

Re: lg 47le5400 powers up, black screen, no sound

You count the pins wrong, please upload good clear pictures of the connector and the pin labels as printed on the board, it helps to show pictures of your power supply board since there are more than one version of the boards used in this TV model.
https://www.shopjimmy.com/catalogsea...?q=lg+47le5400
The connector has odd column number pins and even column number pins.

[maxim22]

Re: lg 47le5400 powers up, black screen, no sound

In PowerOn mode all voltages seem to be OK except PowerOn voltage (pin 1) which is 3.23V instead of 20V (as written on the board).
In StandBy mode there is only 3.4 V on 2 pins (pin5,6), all others are 0V.

I got a light on the screen by 2 jumpers from 3.4 V pins to Drv ON and Power On pins. Previously disconnected power connector on the main board as visible on the picture.
Another picture shows voltages on the connector.

[maxim22]

Re: lg 47le5400 powers up, black screen, no sound

There is also 12.5 V on pins 2,3,4 in the 2nd row from top.

[budm]

Re: lg 47le5400 powers up, black screen, no sound

The exposed pins you see on the top side of the board are the odd number pins, pin 1 is marked with black arrow, the even number pins you you have to probe from the bottom side of the board or from the backside of the female connector.
So if you have all connector in place but you do not have DRV-ON which is from the main board then you need to troubleshoot the main board next.

[maxim22]

Re: lg 47le5400 powers up, black screen, no sound

The exposed pins you see on the top side of the board are the odd number pins, pin 1 is marked with black arrow, the even number pins you you have to probe from the bottom side of the board or from the backside of the female connector.
So if you have all connector in place but you do not have DRV-ON which is from the main board then you need to troubleshoot the main board next.

The picture with voltages is actually the bottom of the connector. Do you have any tips for the main board? I tried heating the board at 385F in the oven but no luck.

[budm]

Re: lg 47le5400 powers up, black screen, no sound

What you can do to see if other function of the main board, T-CON board, LCD panel are OK or not is to put all the connectors back in place then disconnect the DRV wire going back to the main board and then force on the backlights and see if you will get pictures on the screen, sound, and all the function or not, if not then you have more than just bad DRV control signal.
More likely the MCU needs to be reballed, baking in the oven may or may not work and it is usually go bad again.

[diif]

Re: lg 47le5400 powers up, black screen, no sound

Hi I HAVE THE SAME PROBLEM TV TURNS ON BUT NO BACKLIGHT NO PICTURE NO SOUND.I BAKING THE MAIN BOARD IN THE OVEN 200C ON 10 MINUTES BUT NO RESULTS.TV MODEL LG 42LE5500

It's not a cake, there is no baking involved, you are trying to get the solder balls under the processor to remelt and remake any broken solder connections.
Lead free solder melts at around 220c.

[tvtimmy]

Re: lg 47le5400 powers up, black screen, no sound

That around 428° farenheit. That temp will melt every plastic piece and cause most capacitors to explode.

[diif]

Re: lg 47le5400 powers up, black screen, no sound

That around 428° farenheit. That temp will melt every plastic piece and cause most capacitors to explode.

Probably, I wouldn't know having a BGA rework machine and only knowing centigrade.
The point I was trying to make is that baking at 200c/385f is kinda pointless.

[nomoresonys]

Re: lg 47le5400 powers up, black screen, no sound

Only a temporary fix if successful, trick is to melt the solder under the chip, OVERHEATING can kill the chip, lots of videos on youtube, one guy uses an old repurposed halogen floor lamp.

[diif]

Re: lg 47le5400 powers up, black screen, no sound

I watch some videos on YouTube they put the motherboard in the oven because Im not professionalI think that will help but nothing can I try with with hair dryer I dont have heat gun

If it gets hot enough yes a hair dryer can be used. I have also seen examples where a tea light candle was used.

https://www.geektechnique.org/projec...rd-repair.html
https://www.overclock.net/forum/69-n...-tealight.html

Probably safer than heating the whole board in the oven to 220c.

Perhaps it would be worth investing in a cheap thermometer/thermocouple so you know the correct temperature has been reached. Also don't forget flux.