55LA6205UA LG with unusual issue

engyshe · 10-28-2020, 02:42 PM

TV works for 20 minutes. Then the screen goes black but the sound stays on. It comes back normal after 90 minutes (not seconds). If I turn off the TV and then back on again before about 90mins, it will flash the LG logo briefly then will be black again. Unplugging the TV and plugging it back in makes no difference.
I do not understand where this timeout of 90 minutes could possibly be coming from. Any ideas. Thank you

**neilc6** · 10-28-2020, 03:52 PM

https://techhometravel.com/lg-ln-ser...ed-backlights/

engyshe · 10-29-2020, 08:42 AM

Thank you

**jjanssen7** · 10-29-2020, 12:59 PM

I believe the center connectors on on the LED strips go bad on that model sometimes. Something worth checking when all the LEDS work and then BL shuts off after 60 minutes or so.

**budm** · 10-29-2020, 02:40 PM

Try turning down backlights level (not Brightness) to as low as possible to see if it will stay on longer than 90 minutes.

engyshe · 10-29-2020, 03:28 PM

Thank you all

engyshe · 10-29-2020, 03:38 PM

Thank you all. Now that I think about the suggestion of center connections going bad, it totally makes sense. That is the only thing that can explain 90 minutes off time after 20 minutes on time with LEDS being actually ok. With active heat it takes 20 minutes to stretch the led strip and 90 minutes to contract back to the original length and make contact again. This was cool. Thank you

engyshe · 10-31-2020, 09:42 AM

Here is a crazy idea. Would placing a 3/4" wide Kapton tape over the center connection be counter productive in any way. I do not see how (the tape is designed for high temperatures, it is not electrically conductive, it is ESD safe, holds well). If this is truly a failure mode, it means that LG failed in the design between the mounting of the LEDs and the strip temperature expansion, and help to re-enforce the joints would be a good idea.

**jjanssen7** · 10-31-2020, 11:58 AM

it only takes the slightest "tap" to reconnect the leds, so that suggests the problem may be with the electrical contacts themselves as well as thermal expansion. I think the only fix is to solder jumpers across the connections.

engyshe · 10-31-2020, 01:44 PM

Quote:

Originally Posted by jjanssen7

it only takes the slightest "tap" to reconnect the leds, so that suggests the problem may be with the electrical contacts themselves as well as thermal expansion. I think the only fix is to solder jumpers across the connections.

Again thank you for the help.

Cheers

10-28-2020, 02:42 PM	#1
engyshe New Member Join Date: Jan 2015 City & State: Kitchener My Country: Canada I'm a: Knowledge Seeker Posts: 14	55LA6205UA LG with unusual issue TV works for 20 minutes. Then the screen goes black but the sound stays on. It comes back normal after 90 minutes (not seconds). If I turn off the TV and then back on again before about 90mins, it will flash the LG logo briefly then will be black again. Unplugging the TV and plugging it back in makes no difference. I do not understand where this timeout of 90 minutes could possibly be coming from. Any ideas. Thank you

10-28-2020, 03:52 PM	#2
neilc6 Badcaps Veteran Join Date: Nov 2015 City & State: BC My Country: Canada I'm a: Knowledge Seeker Posts: 994	Re: 55LA6205UA LG with unusual issue https://techhometravel.com/lg-ln-ser...ed-backlights/

10-29-2020, 08:42 AM	#3
engyshe New Member Join Date: Jan 2015 City & State: Kitchener My Country: Canada I'm a: Knowledge Seeker Posts: 14	Re: 55LA6205UA LG with unusual issue Thank you

10-29-2020, 12:59 PM	#4
jjanssen7 Badcaps Veteran Join Date: Nov 2012 City & State: Chilliwack, BC My Country: Canada I'm a: Professional Tech Posts: 221	Re: 55LA6205UA LG with unusual issue I believe the center connectors on on the LED strips go bad on that model sometimes. Something worth checking when all the LEDS work and then BL shuts off after 60 minutes or so.

10-29-2020, 02:40 PM	#5
budm Badcaps Veteran Join Date: Feb 2010 City & State: S.F. Bay area My Country: USA Line Voltage: 120V 60Hz I'm a: Knowledge Seeker Posts: 39,043	Re: 55LA6205UA LG with unusual issue Try turning down backlights level (not Brightness) to as low as possible to see if it will stay on longer than 90 minutes. __________________ Never stop learning Basic LCD TV and Monitor troubleshooting guides. http://www.badcaps.net/forum/showthr...956#post305956 Voltage Regulator (LDO) testing: http://www.badcaps.net/forum/showthr...999#post300999 Inverter testing using old CFL: http://www.badcaps.net/forum/showthr...er+testing+cfl Tear down pictures : Hit the ">" Show Albums and stories" on the left side http://s807.photobucket.com/user/budm/library/ TV Factory reset codes listing: http://www.badcaps.net/forum/showthread.php?t=24809

10-29-2020, 03:28 PM	#6
engyshe New Member Join Date: Jan 2015 City & State: Kitchener My Country: Canada I'm a: Knowledge Seeker Posts: 14	Re: 55LA6205UA LG with unusual issue Thank you all

10-29-2020, 03:38 PM	#7
engyshe New Member Join Date: Jan 2015 City & State: Kitchener My Country: Canada I'm a: Knowledge Seeker Posts: 14	Re: 55LA6205UA LG with unusual issue Thank you all. Now that I think about the suggestion of center connections going bad, it totally makes sense. That is the only thing that can explain 90 minutes off time after 20 minutes on time with LEDS being actually ok. With active heat it takes 20 minutes to stretch the led strip and 90 minutes to contract back to the original length and make contact again. This was cool. Thank you

10-31-2020, 09:42 AM	#8
engyshe New Member Join Date: Jan 2015 City & State: Kitchener My Country: Canada I'm a: Knowledge Seeker Posts: 14	Re: 55LA6205UA LG with unusual issue Here is a crazy idea. Would placing a 3/4" wide Kapton tape over the center connection be counter productive in any way. I do not see how (the tape is designed for high temperatures, it is not electrically conductive, it is ESD safe, holds well). If this is truly a failure mode, it means that LG failed in the design between the mounting of the LEDs and the strip temperature expansion, and help to re-enforce the joints would be a good idea.

10-31-2020, 11:58 AM	#9
jjanssen7 Badcaps Veteran Join Date: Nov 2012 City & State: Chilliwack, BC My Country: Canada I'm a: Professional Tech Posts: 221	Re: 55LA6205UA LG with unusual issue it only takes the slightest "tap" to reconnect the leds, so that suggests the problem may be with the electrical contacts themselves as well as thermal expansion. I think the only fix is to solder jumpers across the connections.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode