Mulja tv repair portal

Equipment Repairs => LCD TV forum => Topic started by: EVILMRB on May 11, 2020,22:29:28

Title: LG 42LN575V-ZE std by flashes 3 times
Post by: EVILMRB on May 11, 2020,22:29:28

Hi any help would be appreciated I have a LG 42LN575V-ZE and the problem is when i press the remote to come on the led flashes 3 times then blank no picture or sound so I have checked all the voltages on the power board and have the std by 3.5v two  12v and a 24v feed. I have read that people have been baking the main board due to the xd engine ic not having very good contact with the board but I don`t want to go that far yet until I have looked at other possibilities. Also I am getting the the right voltages from the led side of the power board as well..

Thanks Lee

Title: Re: LG 42LN575V-ZE std by flashes 3 times
Post by: downunder on May 12, 2020,03:23:01

Hi Lee, Do you have an LG service remote - an invaluable tool for recent LG TVs? Press the IN START button then if the menu appears, select POWER OFF STATUS. It will give a log of the power-offs and the cause.

Check the psu-main connector on the PSU and see if you're getting a 3V+ INV. ON signal at switch on and see if it stays there. If no signal, then the main board is faulty. In which case cooking will usually restore it, but this is seldom a permanent solution.

I'd also suspect the backlight LEDs. Common in LGs.                                Bruce

Title: Re: LG 42LN575V-ZE std by flashes 3 times
Post by: EVILMRB on May 12, 2020,16:36:38

On the psu connection there is Drv-On which is giving out nothing.. Here is a pic of the board.

Title: Re: LG 42LN575V-ZE std by flashes 3 times
Post by: downunder on May 13, 2020,03:10:32

Well there's your problem - main board is faulty. DRV ON = INV ON = BL ON. PSU is generating required voltages with the application on
P ON. So while the TV is "ON" connect a wire between 3.5V pin and DRV ON. The backlights should be seen to light up if the LEDs are OK.
You can then safely say the main board is faulty.                                           Bruce

Title: Re: LG 42LN575V-ZE std by flashes 3 times
Post by: EVILMRB on May 16, 2020,19:39:26

Hi The main board is at fault so I have now sent for a replacement.Thank you for your help and advice very much appreciated.

lee