LG 60LB7100 screen goes black seconds after start up

[tstew]

Re: LG 60LB7100 screen goes black seconds after start up

I'm guessing nobody else has any ideas?

[budm]

Re: LG 60LB7100 screen goes black seconds after start up

Can you leave the black probe on the chassis, and read probe on the connector P201 pin 4 (P-DIM) to see what DCV you have when the Bakclights come on for seconds? Notes: to get to the EVEN pins of the connector you will have to get to the bottom side of the board or through the wire entrance of the connector, you can get to all the ODD pins on the top side of the board.
Do the same on P-DIM2 pin.

[kudalski]

Re: LG 60LB7100 screen goes black seconds after start up

Problem is not coming from either of the boards. Main board tested in another TV and it works perfect. power supply board replaced twice...same problem existed unless both power supply board that I got from eBay have this problem. I doubt it.
I took the screen apart and all light work and look healthy for the 10 seconds they come on.
Tried disconnecting one of the LED strips to act an open LED the set only gave me about 3 seconds of LED illumination the cut off. That tells me LED current flow sensing circuit is working accordingly.

Its a damn weird ass problem! if anyone got any suggestion please post. Thank you.

[kudalski]

Re: LG 60LB7100 screen goes black seconds after start up

Went back one more time into the LED's and found the 2 upper strips tend to go out. going to replace then will come back and update

[kudalski]

Re: LG 60LB7100 screen goes black seconds after start up

Problem solved.
Weak or going out one of the LED Strips. Changed (replaced one surface mount LED on one of the strips). Set is perfectly fine now.

[Louie728]

Re: LG 60LB7100 screen goes black seconds after start up

Hey All I am having this same issue. The tv comes on show the picture bright for a few seconds then all goes black, sound is ok but it appears like no picture. If I take a flash light and shine on the TV I can see that the picture is there. I assume that it is the LED strips. I am by no means an expert but really woulk like to be able to replace myself if possible. Is this something that I could do? shopjimmy is out of stock on https://www.shopjimmy.com/lg-6916l-1...-12-strips.htm but it appears that I can get here http://www.tvpartscentral.com/lg-691...ips-12-strips/ .. Any help greatly appreciated.

[dskall]

Re: LG 60LB7100 screen goes black seconds after start up

Youtube has lots of videos on replacing backlights

[kudalski]

Re: LG 60LB7100 screen goes black seconds after start up

Hey All I am having this same issue. The tv comes on show the picture bright for a few seconds then all goes black, sound is ok but it appears like no picture. If I take a flash light and shine on the TV I can see that the picture is there. I assume that it is the LED strips. I am by no means an expert but really woulk like to be able to replace myself if possible. Is this something that I could do? shopjimmy is out of stock on https://www.shopjimmy.com/lg-6916l-1...-12-strips.htm but it appears that I can get here http://www.tvpartscentral.com/lg-691...ips-12-strips/ .. Any help greatly appreciated.

I'd say you'd have to be a bit advanced to do this. I been fixing TV's and computers since 1993.

You got to be very careful you can easily crack the screen taking it a part.
Once the screen is off you can turn the TV on and quickly look see which of the LED's is out. See the strip part # look and order it eBay or shopjimmy.

If you want to get more technical then replace the actual defective LED. Clip the LED lens of it, replacing actual LED requires some carful soldering skills (plastic tiny LED burns easily with excessive heat).

Once LED replaced and all LED's work and TV stays on what I would do is put back the LED lens using epoxy glue, line it up so the light is spread out or (you will see a shadow of light in the picture when done). Wait a few minuets for epoxy to dry

Reassemble TV.

[Louie728]

Re: LG 60LB7100 screen goes black seconds after start up

Thanks for the reply guys. I am just going to replace all 12 strips ..

I would say Im not total novice so I think I will be ok. To make sure I wont screw up the screen im gonna use this disassemble method
https://www.youtube.com/watch?v=5rwLDxKgZIA

Thanks

[budm]

Re: LG 60LB7100 screen goes black seconds after start up

That looks easy but sometime that glass LCD panel get stuck to the rubber cushion strips on the black plastic frame. Just take your times is the key.
Also re-solder the connector SMD pins that links the LED strip together, it comes loose from the board every easily.

[Louie728]

Re: LG 60LB7100 screen goes black seconds after start up

Thanks for your help guys. I ordered the whole array and only needed to replace one strip (determined by turning on while disassembled and I could tell the failing led). The whole job took about 2 hours because I took my time. TV is working fine now. I will probably keep 2 a strips and 2 b strips and put the rest on eBay.

[Louie728]

Re: LG 60LB7100 screen goes black seconds after start up

I had to do this again on another LED strip. This time I reassembled and there are lines down the middle of the tv and horizontal on the bottom. the lines move also if you move the tv. I didnt have time to take apart agai last night. Did I break something? Did I not assemble correctly? Im just wondering if I should waste my time.

[dick_barton]

Re: LG 60LB7100 screen goes black seconds after start up

Check the LVDS cable(s) from the Tcon to the panel very carefully and check that the fine gold contacts on the cable are not damaged, which can happen very easily.

[Louie728]

Re: LG 60LB7100 screen goes black seconds after start up

if the cable is damaged. is this replaceable? Worth it?

[dick_barton]

Re: LG 60LB7100 screen goes black seconds after start up

They are replaceable but I don't know what it would cost.

[Tws]

Re: LG 60LB7100 screen goes black seconds after start up

I'm having the same problem with same TV. My voltages are led=82v off=55 v. Vc_1=35v off=14.30v. Vc_2=28v off=4.6. vc_3=13v off=11.5v. Vc_4=13 off=11.5. vc_5=13.5 off=11.5. vc_6=13.5 off=11.5. any info would be greatly appreciated. Thanks