LG55UB850V no picture or audio - flashing LED's help please?

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

Stencils are available for the LG chips but the last one I did I used a universal stencil and a bit of kapton tape to mask off the inner part where there are no balls.

Thanks for the info, good to know the stencils are available at least

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

this issue to me look like when you start the car but the starter keep on LOL... he had some kind of script repeat it self to take place.. however he tried to heat. and disconnect MICOM action. but i do suggest to freeze but he went to heat.. because the tv was turning on but not complete no panel vcc and optical ports still until now didn't lit on. i would start freezing instead of heating..

I see where you are coming from with the starter motor on a car analogy!

Are you able to provide any guidance for the freezing process - happy to try this but not sure how to go about it exactly?

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

This maybe a set that gets put aside for a while in the hope a replacent mainbord becomes available does the likes of shopjimmy etc list a alternative board?
i thinkk this forum has a for sale/wanted section maybe post in that thread too regarding a working mainboard needed.

Thanks, i'll check shopjimmy for any info on alternative boards to see if any exist for this model. I'll get an ad put in the for sale/wanted section on here too, thanks for the suggestion

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

Removed the heatsink from above IC2500 and the DDR chips

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

align and solder the marked cap

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

OK done



and I've also straightened out C2348

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

OK done ....and I've also straightened out C2348

good work.. please after any attempt for repair or corrector you need to test the TV.

this time if it remain same issue i would like you to feed the tv HDMI signal so we will know if the circuit of HDMI work video and sound.

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

Thanks, that tiny cap was tricky with a small basic magnifying glass and a steady hand!

OK I plugged the MB back into the TV and still exactly the same behaviour as before.
Oddly, I was seeing the LD1900 flickering on and off randomly at first, so I immediately thought "oh no I've introduced a new problem with my soldering"
Thankfully not - it turned out to be a bad connection between the LVDS cable and the T-Con board. Fiddled about and unplugged it a couple of times and back in again and now it is working solidly. I've tried getting it to fault again by poking it and moving it a little but it's working fine so must have just been a bad connection.

I have plugged an HDMI device into each of the 4 HDMI connectors and the TV displays both video and audio output on all 4 ports absolutely fine - just with the 2 second cycle of buzzing and bad picture still. So the HDMI side of the board seems to be fine.

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

okay.. good result with HDMI. the 2 seconds as i said before belong to script.. because only this part can repeat at exact time 2 seconds as you said.

IC2500 had the connection to LD1900 (page 52 SM ) and to the SPI Flash IC1901(page 55 SM ). so i think this 2 ICs are the suspected of the timing issue and they are now to me like enemy's LOL

so locate first IC1901 on boards.

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

after you locate IC1901, i would suggest you to focus on the SPI as need to try SW1901 URSA_RESET press keep press then turn on the tv... you can try too by press long pressing while the tv on.. also you need to have freeze air spray to freeze it and turn on.. we need to let it have action at any cost. all of these try always your eyes on Optical ports if it lit on.

[vinceroger69]

Re: LG55UB850V no picture or audio - flashing LED's help please?

If you have no freeze spray this is what i use good price from amazon https://www.amazon.co.uk/FREEZE-SPRA...1NBISVQ1&psc=1

[diif]

Re: LG55UB850V no picture or audio - flashing LED's help please?

If you have no freeze spray this is what i use good price from amazon https://www.amazon.co.uk/FREEZE-SPRA...1NBISVQ1&psc=1

It's over £2 cheaper to buy from ebay https://www.ebay.co.uk/itm/384666824914
Also butane (lighter gas) can be used if you're cheap/want it quick/like a bit of danger. Exercise caution though.

[vinceroger69]

Re: LG55UB850V no picture or audio - flashing LED's help please?

It's over £2 cheaper to buy from ebay https://www.ebay.co.uk/itm/384666824914
Also butane (lighter gas) can be used if you're cheap/want it quick/like a bit of danger. Exercise caution though.

amazon one is 600ml so worth the extra £2.00 in my opinion never tried butane before tried the cheap air duster though.

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

butane (lighter gas) !!!! MY GOSH i smell TERROR mind LOL... the biggest failure in life could start with just little spark. NO WAY to chose short DEATH WAY to safe small potato £ / $ / € either Chinese WON CNY

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

Thank you for the links to the Freeze spray - I don't have any so will get a can of that ordered today. I don't mind waiting a few days for it to arrive.

I have located IC1901 SPI Flash - winbond W25Q32BVSSIG



I have also tried the reset again - holding SW1901 before turning on the TV and also holding it down while TV is on for several seconds. This hasn't made any difference.
When testing using this reset button, I did notice the following. If TV is on and doing the 2 second cycle, as soon as I press SW1901 and hold it down, the buzzing stops and the LD1900 goes off, and if I keep SW1901 held down, LD1900 stays off, however after around 3 or 4 seconds the buzzing cycle starts again, even with SW1901 still held down and LD1900 off.

Likewise, if I hold SW1901 down and then turn on TV, this prevents LD1900 form lighting up, and the 2 second buzzing cycle carries on regardless.

During both above tests, still no sign of life at the optical audio port.

I will need to wait for the freeze spray to arrive, but when it does I will try freezing IC1901 and see what the results are.

Is it possible that IC1901 is stuck in a sort of 'boot loop' like a windows computer? Although in windows, you never actually get to the fully loaded desktop - it just keeps falling over and booting time after time.
Whereas with the TV, it does boot up enough for the TV to function in terms of menu's, HDMI etc, just with the cycling of buzzing and video issue.

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

do you have on IC1901 PIN 8 stable 3,3V

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

While the TV is in standby I have stable 0.138v at pin 8 of IC1901
While the TV is powered on I have stable 3.271v at pin 8 of IC1901, even during buzzing, it is stable.

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

I have stable 3.271v at pin 8 of IC1901, even during buzzing, it is stable.

good.. you need to check all USB ports if they are working to be sure the 5V exist.

EDIT: in case you have USB Ports working.. then

you can work on SW level for downgrade then update until you got freeze spray

this is version 04.30.16 from 9.2014
this is version 04.45.25 from 22.06.215

this is version 04.65.05 from 03.2015 for south Africa

search after Apache server for downgrade LG TV i wrote over here and you can find it on github too.

[Scoff]

Re: LG55UB850V no picture or audio - flashing LED's help please?

Ok all 3 USB ports are working correctly and recognise my USB flash stick. I am getting 5.115v on pin 1 at USB connections.

I will have a look for the downgrading of firmware instructions - thank you for those firmware links. I will report back with progress updates.

[Diah]

Re: LG55UB850V no picture or audio - flashing LED's help please?

this issue abnormal to me .... so for record only i searched my notebook which its 500 pages i used until now to write down set ( not only TV ) brand and the issue and causer.. to be easy for my brain later some how my memories become weak...
searching after buzzer on T-CON ... over all causes i faced at trouble shooting . 11 cases different sets (brand), all of them 100% caused by ribbon cable pins damage. OP said they are fine... !

EDIT if OP sure 10000000% all ribbon from both side are absolute fine... then you have pin soldering short under IC2500