LG 55LE5400 Flashing and buzzing

[jason123]

Hi,
I would greatly appreciate any insight of what this issue could be before I open it up and start the typical troubleshooting. I have and LG 55LE5400 TV, that turns on beautifully, backlight ok, steady picture (logo), then when it fully boots you start hearing a buzz / high pitch, then the picture starts flashing - you can still see the prompts on the TV (like input source selected and so on ) just the buzzing stays and picture continues to flash. I included a short 27 second video since it's difficult to describe this. Any thoughts?
Thank you

[freakaftr8]

Re: LG 55LE5400 Flashing and buzzing

First thing that comes to mind is LG and failing leds. I would disconnect the LED backlighting from the power supply and then power up the TV and see if the buzzing still occurs. When the picture comes up before it shuts down do you see any dark areas?

[jason123]

Re: LG 55LE5400 Flashing and buzzing

Thanks Freakaftr8 - I will try that a bit later.. it's good start. I wouldn't have thought of it, because the backlight comes on steady while the logo is showing.. it's only when "Other things" start coming on that the flickering starts

[freakaftr8]

Re: LG 55LE5400 Flashing and buzzing

This era of main boards present a problem with bad BGA soldering connections on the nvram for the processor. It will represent themselves in various different fashions that could also be looked at

[jason123]

Re: LG 55LE5400 Flashing and buzzing

So I opened it up and the buzzing was actually coming from the speakers. Disconnecting the LED power from the LED Driver board didn't have any effect.. disconnecting the speakers took care of the buzz, but the picture is still shaky / flickering. Any thoughts?

[freakaftr8]

Re: LG 55LE5400 Flashing and buzzing

Have a look at this post and try the methods within and tell us if you have results

https://www.badcaps.net/forum/showthread.php?t=61321

[dskall]

Re: LG 55LE5400 Flashing and buzzing

With buzzing speakers could be a bad cap on mainboard. Possibly power board. You could go around and check across caps with meter set on ac and see if any measure higher than others.

[jason123]

Re: LG 55LE5400 Flashing and buzzing

Thank you.
dskall, am I looking for higher ESR or Shorted? higher ripple?
Thanks

[dskall]

Re: LG 55LE5400 Flashing and buzzing

Might have a look at this :https://www.youtube.com/watch?v=LvXe0bOF_mk

[jason123]

Re: LG 55LE5400 Flashing and buzzing

Thanks Dskall. Good video. I've done something similar, but given most capacitors are on different regulators, I don't have something to compare to. Here is some more info:
- The Ethernet port is not powered (when connected to a network switch - no activity)
- Firmware upgrade through USB results in no activity. Though I see the USB being powered up, for some reason, the system doesn't detect the presence of a USB flash drive.
- Menus for Network have Network config and Network status greyed out.
-Only power coming into the board is 24 V and that seems to be solid (24.16 V)
- I checked many capacitors on the main card, and they all read either 11.9, 3.3, 1.5, 1.8.. which is typical from what I recall.. one set of caps is reading 7.8 V which is odd.. I don't remember that voltage rail on other board. These are the C9114 and C9115 (assuming someone has a schematic for this EBU60884404)

Thoughts?

[jason123]

Re: LG 55LE5400 Flashing and buzzing

Just to note.. as the TV warms up.. the buzzing noise quiets down quite a bit.. and the flashing stops.. but still no Network or USB access

[freakaftr8]

Re: LG 55LE5400 Flashing and buzzing

Like I said suspect BGA rework on the NV Ram modules around the processor try heating them up and see if the problem goes away as a TV starts up cold..... these are located underneath and around the black heat sink

[jason123]

Re: LG 55LE5400 Flashing and buzzing

Thanks Freakaftr8.. I have access to a reflow machine and technician.. it's going through that now.. I'll update shortly.

[freakaftr8]

Re: LG 55LE5400 Flashing and buzzing

Sounds good but I wouldn't not go through the process and Reflow unless necessary. A simple hair dryer will do the trick while the TV is on cold

[jason123]

Re: LG 55LE5400 Flashing and buzzing

Thanks Freakaftr8 .. great success with Reflowing the processor. I'm getting almost all functionality back, except the Network!
This unit has Ethernet port and it's "WiFi" ready. The Ethernet port is not showing any activity what so ever. Options in Menu still greyed out, LEDs on the connector stay off even when there is a good link... any suggestions? I updated the Firmware using a USB drive - so that was great..

[freakaftr8]

Re: LG 55LE5400 Flashing and buzzing

Interesting. Ethernet internally is not getting powered. Can you factory reset? It's in the settings menu.

[jason123]

Re: LG 55LE5400 Flashing and buzzing

I did.. then I upgraded firmware and tried again.. still greyed out for some reason