LG 65UH5500 Momentary Flash Of BackLights

[budm]

Re: LG 65UH5500 Momentary Flash Of BackLights

Ohmigod!!! Ohmigod!!!

In an effort to confirm once and for all that the LEDs are not the problem, I hit on the idea of taking each pair of wires off of the DRIVER connector and place them on the DRIVER board one pair at a time..

Each pair gave me the same thing.. An LED strip/area came on then flashed off... So, that told me that the LED array is NOT the problem..

After I had tested the last pair, I put them back into the connector and then plugged the connector back into the DRIVER board...

Powered up the TV and, I'll be at some beach, the LEDs came on and stayed on!!!!

I thought to myself, I said, "Self!? Well, ya fixed the LED issue, but you still don't have an display.."

And, some beach again, I sure had a display!!!???

Apparently, it's all linked together.. You can't have a display if the LEDs aren't coming on and staying on...

So, not one to look a gift horse in the mouth, I am gonna count this one as a win!!

Thanks again to all who helped out...

That is good to know about these newer Samsung that it links the Video circuit to the backlights circuit, it still does not make sense why they need to to do that.. I also wonder if what they did is to kill the switched 12V to the T-CON if the backlights circuit fail. I usually see they kill the PS-on OR BL-ON if there is problem with backlights.

[Michale32086]

Re: LG 65UH5500 Momentary Flash Of BackLights

That is good to know about these newer Samsung that it links the Video circuit to the backlights circuit, it still does not make sense why they need to to do that.. I also wonder if what they did is to kill the switched 12V to the T-CON if the backlights circuit fail. I usually see they kill the PS-on OR BL-ON if there is problem with backlights.

Hope it's not a trend... Makes it that much harder to diagnose..

[Michale32086]

Re: LG 65UH5500 Momentary Flash Of BackLights

Well, I guess it WASN'T "fixed" after all..

After two days of sitting, turning on and off occasionally to admire the awesome graphics, the TV shut off and is now doing the same thing... Power up, get a flash of the LEDs and then they shut off and no display... And the TV cannot be turned off

Something different now, though. When I put the NEW Main Board in I had purchased and power up the TV, the TV stays off.. I push the power button and the power LED blinks, the LEDs come on bright, then dim then shut off and the TV turns off... Solid LED on the power light.. I push the power button and the power LED blinks a couple times, nothing happens on the backlights and the power LED goes back to steady...

This TV is simply too nice of a TV to give up on..

[Michale32086]

Re: LG 65UH5500 Momentary Flash Of BackLights

Received replacement LED DRIVER BOARD....

Same problem...

As much as I don't want to, I am thinking I have to pull off the display panel and access and check the LED strips directly..

NOT looking forward to that...

[Michale32086]

Re: LG 65UH5500 Momentary Flash Of BackLights

OK, got in the shop about 0200 and prepped the table to break down a 65" LG to the bare LEDs...

Wasn't fun, but I did get to use my handy dandy Harbor Freight Suction handles.. I had a friend pick me up a pair of the single suction ones. I had actually wanted the dual suction for less concentrated stress...

The single ones worked like a champ.. Was able to lift off the panel with ease and no major warpage..

So, that part of the surgery was a success..

OK, so I discover that a set of 4 LED strips are not coming on... They are linked to the DRIVER board all on the same paired connection. So I am immediately thinking a bad wire pair.. Especially since I check each strip with my LED power source and they all work.. Or so I thought...

So, after an hour of fiddling with the pair of wires, crimping here and testing connectivity there, I am stumped...

I figure, why not put that strand on a different set of LEDs and see what's what. Well, the wire pair worked fine on a different set of LEDs... So, that tells me the wire pair is fine..

So, I go back to thinking bad LED strip.. I start swapping out each LED strip (there are 4) to a different area of the array... First one I swap out, THAT set goes dark and the original set is fine.. Just to be sure, I test the other 3.. They are all good..

So, I am left with the only logical conclusion that I have a single bad LED strip.. Test it with my LED PS and, sure nuff, it's bad... Only thing I can think of is my brain hadn't fully woke up...

So, anyways, a replacement LED strip would be $60 and a week away... This 4K TV is obviously work another $60 outlay, but I don't want to wait a week.. Tear thru all my LED strips ( I have a ton of them) and find a similar one with similar LED positioning...

Hook it into the array (had to do some jury rigging) and 'viola!!

One each-type working LED Array!!

[dibsrepair]

Re: LG 65UH5500 Momentary Flash Of BackLights

Got an update on this tv?

[Michale32086]

Re: LG 65UH5500 Momentary Flash Of BackLights

Got an update on this tv?

Yea, and it's a sad story...

https://www.badcaps.net/forum/showthread.php?t=70131

[anthonystv]

Re: LG 65UH5500 Momentary Flash Of BackLights

Ground the fail pin and turn the tv on

[Splenker]

Re: LG 65UH5500 Momentary Flash Of BackLights

Have an LG65uh5500 same issue. If you disconnect the connector from the led driver board to the main board and connect your meter lead to one of the 80vdc connectors on the psu then reconnect the mainboard plug the tv in the psu momentarily flashes the 80vdc then returns to the lower,in my case 63.5vdc. I am wondering if the mainboard is seeing a defective led and returning to standby voltage. Also the led strips momentarily flash on on first powerup.

[neilc6]

Re: LG 65UH5500 Momentary Flash Of BackLights

Though this thread is a bit convoluted, a momentary flash of backlights on a LG LED tv is a symptom of bad and failing backlights. You can confirm with a LED tester or watching them flash with the panel removed. I would do a full replacement of all strips.

[jjanssen7]

Re: LG 65UH5500 Momentary Flash Of BackLights

100% agree, as replacing just the affected strip means the next one will fail weeks later.

Though this thread is a bit convoluted, a momentary flash of backlights on a LG LED tv is a symptom of bad and failing backlights. You can confirm with a LED tester or watching them flash with the panel removed. I would do a full replacement of all strips.

[Splenker]

Re: LG 65UH5500 Momentary Flash Of BackLights

Do you have to remove the scan drive boards at the bottom of the tv to access the backlights.

[neilc6]

Re: LG 65UH5500 Momentary Flash Of BackLights

https://youtu.be/5ir7mXun8KU

[Splenker]

Re: LG 65UH5500 Momentary Flash Of BackLights

Found one bad backlight strip. replaced and tested all the backlights reassembled TV same issue. Any suggestions

[Splenker]

Re: LG 65UH5500 Momentary Flash Of BackLights

GND the fail pin and turned the TV on same issue. Momentary flash of the backlights and the tv goes off.

[neilc6]

Re: LG 65UH5500 Momentary Flash Of BackLights

You probably still have a bad led or a bad connection. I always turn on the tv with the panel disconnected to check the backlights before reassembling.

[Splenker]

Re: LG 65UH5500 Momentary Flash Of BackLights

Would have to be a bad connection checked all the strips before reassembly. any other suggestions??

[nomoresonys]

Re: LG 65UH5500 Momentary Flash Of BackLights

Could be a bad connection, here's a reset to try:
Press and hold the Volume Down button and don't let it go.
Now, press and hold the Power key while holding down the Volume Down button.
Keep both keys held for 20 seconds or more.
When the logo appears, release both keys.

[nomoresonys]

Re: LG 65UH5500 Momentary Flash Of BackLights

These lgs have a pretty bad rep, just been reading where people replaced every board and strips with no luck, a few but not most had success with baking or heatgun reflows.

[Pitoniak]

Re: LG 65UH5500 Momentary Flash Of BackLights

Where is the main filter cap you are talking about on the ps bd?