Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting TVs and Video Sources
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 01-26-2022, 06:13 AM   #1
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default LG55UB850V no picture or audio - flashing LED's help please?

Hi, I'm looking for some help with attempting to troubleshoot and hopefully repair my trusty LG55" TV.

I'm reasonably comfortable working with electronics, but far from expert level! I have more experience with auto-electrics than anything.

We recently had a power cut while the TV was on, and since then, when the TV is switched on at the wall, the red standby light comes on like normal. Then. when you press the power button on the remote or the TV to switch it on from standby, the standby light flashes 3 times and then goes out. There is no audio or video at all and no LG logo on the screen. The screen stays completely black. I've used a flashlight to check and there is no life on the screen at all.

The model is LG 55UB850V. I have taken the back off the set and observed the following internally.
The power supply board is model PCB: EAX65613901 (1.6), LG P/N: EAY63149401 REV 1.0 2014.01.27
The Main Logic board is model L#41V EAX65684604 (1.0)
The T-CON board is mode V14 TM120 UHD Ver 0.6, LG P/N: 6870C – 0502C

When the set is in standby mode, there are no LED’s lit up on either the power supply board or the main board. When I press the power button on the remote or the TV, the red standby led flashes 3 times and then goes out. The red led LD2300 on the main logic board is lit up solid and the red led LD1900 on the main logic board lights up briefly for around 1 second then goes out.

After 60 seconds in this state, the amber LED LD701 on the power supply board starts flashing a sequence of 5 flashes, and then 5 seconds off, then 5 flashes, then 5 seconds off etc. This carries on seemingly indefinitely.
During this time there is absolutely nothing on the screen.

If I leave the set in this state, as if the screen should be on, and with the amber LED LD701 repeatedly flashing it's 5 flash sequence, for around 20 minutes or so, then use the remote to put the set back into standby, then again use the remote to turn the set on form standby, it springs back into life.
It seems the set needs to have constant power, in the normal 'on' state for around 20 minutes or so before it will then start to work, once put into and back out of standby.

Can anyone suggest what might cause this behaviour? If I unplug the set form the mains, and then plug it back in again, it fails to work, until I have left it in the 'on state for 20 minutes or so.
Could this be cause by failing capacitors that are unable to keep their stored voltage once the mains power is cut? Could it take 20 minutes or so for them to get to full capacity in order to allow the set to start functioning correctly?
The 28 pin connector on the power board has all the correct ground, 3.5v, 12v, and 24v readings when tested, even when the screen isn't on or working.

Thanks for any help!

EDIT: My 20 minute theory has gone out the window - it must have just been a fluke that it started working. During this 'working' spell, the tv was still face down on my bed with the back removed while I was testing. After reassembling the back and putting the TV back on its stand, I couldn’t get it to switch on again, even after leaving it in standby as well as in what should be the 'on' state overnight.

After taking the back off again, I can see that what DOES happen after 20 minutes of being in the 'on' state, all LED's turn off, and the red standby light goes solid again - must be some sort of timeout or power saving setting, making it go back into standby mode.






Scoff is offline   Reply With Quote
Old 01-26-2022, 07:33 AM   #2
Diah
Badcaps Veteran
 
Join Date: Feb 2013
City & State: SA
My Country: Germany
I'm a: Professional Tech
Posts: 3,371
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

try unplug the wifi module / speaker socket and turn on.
athe sign of the tv working (as you will put the tv surface on yours bed )take always the Red LED on the audio SPDIF port if it lit on.
Diah is offline   Reply With Quote
Old 01-26-2022, 10:13 AM   #3
dskall
Badcaps Veteran
 
dskall's Avatar
 
Join Date: Oct 2016
City & State: Bakersfield ca.
My Country: usa
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 2,642
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Cutting power to tv can corrupt firmware.
__________________
I assume no responsibility for any stupid suggestions I might post.
dskall is online now   Reply With Quote
Old 01-26-2022, 11:10 AM   #4
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Quote:
Originally Posted by Diah View Post
try unplug the wifi module / speaker socket and turn on.
athe sign of the tv working (as you will put the tv surface on yours bed )take always the Red LED on the audio SPDIF port if it lit on.
You Sir are a genius! I unplugged the 8 pin connector going to the WiFi / Bluetooth module - LGSBW41 EAT62093301





and the TV screen powers up first time every time now! I'm not sure if this will cause any problems by being left unplugged, however I will put the back of the TV back on and see what happens.

Is this a common issue on this model? I imagine it will no longer be possible to buy a 'new' module, only other used ones.
I'm not sure if I can run an ethernet cable to the TV point to use instead, but I would like the WiFi to work if possible. Depending what is wrong with this board, i guess it may be possible to have the board repaired?
Scoff is offline   Reply With Quote
Old 01-26-2022, 11:12 AM   #5
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,358
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

i have seen a couple of wi fi modules fail like this i just purchased a used one from ebay and fixed the issue.
vinceroger69 is offline   Reply With Quote
Old 01-26-2022, 11:46 AM   #6
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Thank you, that's useful to know. When sourcing a replacement board, do you know if it is essential to match the board version number? For example, my board shows LGIT: TWCM-B001D V1.6
I have seen some versions of this board that show V1.7 and also V1.8.

Would I need to get another V1.6 board, or is the version not as important provided I get the identical part numbers? On the V1.7 and V1.8, all part numbers printed on the boards appear to be identical. The only visual difference seems to be that the V1.8 has several CNC-ID numbers printed on it in the upper right area, and the Brand just says LG, compared with LG Electronics on my V1.6 e.g

Scoff is offline   Reply With Quote
Old 01-26-2022, 11:53 AM   #7
Diah
Badcaps Veteran
 
Join Date: Feb 2013
City & State: SA
My Country: Germany
I'm a: Professional Tech
Posts: 3,371
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Quote:
Originally Posted by Scoff View Post
You Sir are a genius! I unplugged the 8 pin connector going to the WiFi / Bluetooth module - LGSBW41 EAT62093301

and the TV screen powers up first time every time now!
disconnection the wifi module its part to remove load on the mainboards.

at LG if you now send IN_STOP command(read about this command over this forum i explained it many time to make hard reset). after it go to reboot plug it out from wall... connect yours wifi again and see if it will assign it again so you can use this future on yours LG
Diah is offline   Reply With Quote
Old 01-26-2022, 11:57 AM   #8
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,358
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

if needed does this one match your board https://www.ebay.co.uk/itm/203443190...QAAOSwnOFgkohD

Last edited by vinceroger69; 01-26-2022 at 12:03 PM..
vinceroger69 is offline   Reply With Quote
Old 01-26-2022, 12:03 PM   #9
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,358
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

lg service remote apk
Attached Files
File Type: zip lgapk.zip (7.96 MB, 18 views)
vinceroger69 is offline   Reply With Quote
Old 01-26-2022, 12:06 PM   #10
nomoresonys
Badcaps Veteran
 
Join Date: Jan 2013
City & State: midwest
My Country: U.S.
I'm a: Knowledge Seeker
Posts: 7,628
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

If that don't work maybe clean it up, demonstration there: https://www.youtube.com/watch?v=xX9bB92UBbA
nomoresonys is offline   Reply With Quote
Old 01-26-2022, 03:34 PM   #11
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Thanks for all the responses and info provided. I'll see if I can knock up an IR Blaster and give that a try so I can send IN_STOP Command. Failing that I'll pick up a used replacement board like the one vinceroger69 kindly linked.
Scoff is offline   Reply With Quote
Old 01-27-2022, 04:37 AM   #12
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,358
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

lg service remotes have certainly dropped in price now i may order myself one
https://www.ebay.co.uk/itm/133978976...3ABFBM7LfTsdNf
vinceroger69 is offline   Reply With Quote
Old 01-27-2022, 05:10 AM   #13
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

I've had a look and can't find any IR LED's in my box of bits, so I'm going to order one of these service remotes instead - thanks for the link!
Scoff is offline   Reply With Quote
Old 01-27-2022, 05:26 AM   #14
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,358
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Quote:
Originally Posted by Scoff View Post
I've had a look and can't find any IR LED's in my box of bits, so I'm going to order one of these service remotes instead - thanks for the link!
that app works on a android phone too i think if you have one.
vinceroger69 is offline   Reply With Quote
Old 01-27-2022, 05:48 AM   #15
Diah
Badcaps Veteran
 
Join Date: Feb 2013
City & State: SA
My Country: Germany
I'm a: Professional Tech
Posts: 3,371
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

IN_STOP are very effective action in such cases as yours. but you can try the factory reset from the TV menu. when it go to start reboot plug out from wall and reconnect your wifi module.. if it come on and u can use the wifi every things mean fine.
Diah is offline   Reply With Quote
Old 01-27-2022, 07:41 AM   #16
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Quote:
Originally Posted by vinceroger69 View Post
that app works on a android phone too i think if you have one.
I have a couple of android phones, but not old enough to run the legacy version of the remote app required. Also they do not have IR Blasters built in.
Funnily enough ,I just came across an old Nokia 3200 phone which does have an IR blaster built in. Now if I can just figure out a way of using it for this application...
Scoff is offline   Reply With Quote
Old 01-28-2022, 01:50 PM   #17
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

OK so I gave up on the IR Blaster idea and ordered an LG Service remote from amazon which arrived today. With the WiFi/Bluetooth module left unplugged, I turned on the TV no problem and pressed the IN_START button just to see some stats and that service screen came up fine showing over 16500 hours of viewing!!
I pressed the IN_STOP button and entered the 0413 code and carried out the hard reset. Once the TV was back at standby I unplugged it and plugged the WiFi module back in, then turned the TV on and it switched on fine and allowed me to join my WiFi network and carry out the initial setup!
I switched it off and back on several times after setting it up and all seemed OK, so I switched it off again and put the back cover back on and mounted it back onto its stand.
Tried turning it on again and nothing, back to square one
So the IN_STOP command seemed to fix it and allow it to boot up with the WiFi module plugged back in, which it wouldn't do before, however it was short lived and now no longer boots again.

Does this confirm my WiFi module is faulty, or could it still be a problem on the logic board which is caused by the load of having a WiFi card connected?
Scoff is offline   Reply With Quote
Old 01-28-2022, 02:05 PM   #18
Diah
Badcaps Veteran
 
Join Date: Feb 2013
City & State: SA
My Country: Germany
I'm a: Professional Tech
Posts: 3,371
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Quote:
Originally Posted by Scoff View Post
then turned the TV on and it switched on fine and allowed me to join my WiFi network and carry out the initial setup!
I switched it off and back on several times after setting it up and all seemed OK, so I switched it off again and put the back cover back on and mounted it back onto its stand.
Tried turning it on again and nothing, back to square one
i think yours problem at the Bluetooth section not the wifi... if you were before to turn off the bluetooth will be fine,, or when it first time turn on and you finish with setting and did IN_STOP again while the module connected could be fine too to reset the module MAC.
Diah is offline   Reply With Quote
Old 01-28-2022, 02:40 PM   #19
Scoff
Member
 
Join Date: Jul 2017
City & State: South West
My Country: Uk
I'm a: Knowledge Seeker
Posts: 74
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Quote:
Originally Posted by Diah View Post
i think yours problem at the Bluetooth section not the wifi... if you were before to turn off the bluetooth will be fine,, or when it first time turn on and you finish with setting and did IN_STOP again while the module connected could be fine too to reset the module MAC.
Thank you. How do I disable Bluetooth and leave WiFi enabled on the module? Is there something within IN_START where I can disable Bluetooth? I can only see WiFi information within IN_START and no Bluetooth information? Here is a picture of IN_START with the WiFi module UNPLUGGED

Scoff is offline   Reply With Quote
Old 01-28-2022, 02:49 PM   #20
Diah
Badcaps Veteran
 
Join Date: Feb 2013
City & State: SA
My Country: Germany
I'm a: Professional Tech
Posts: 3,371
Default Re: LG55UB850V no picture or audio - flashing LED's help please?

Man.. IN_Start or E_Z adjust service menu not for you... never inter it...
now your mudule disconnected.. at normal menu setting the option will be gray ( because no mudule installed )
so just after you exit this service menu plug the TV out from wall socket ( dont turn off from RC )
plug yours module and after it turn on you can send in_stop again to reset MAC. later when every things fine.. go to the menu setting from there turn off bluetooth

Last edited by Diah; 01-28-2022 at 02:52 PM..
Diah is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums © 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 10:52 PM.
Did you find this forum helpful?