LG 50UH5530/5500 backlights test good with LED tester....BUT!

[DXseekerMO]

A few months ago I traded an LG 50UH5530 for services from a friend of mine. It had the single backlight logo flash then no picture at start-up. The diagnostic led to the replacement of one LED strip, sourced from fleabay and out of a new freight damaged TV.

Fast forward to this weekend....when my friend tells me the backlights went out again, same backlight logo flash then no picture. Based on his description and to save him time I went ahead and pre-ordered all new backlight strips from ShopJimmy.

So last night I went and got the TV, opened it up, pulled the panel and checked each backlight strip with the LED tester. I was puzzled when all the strips lit up and tested at about the same parameters.

It took me a bit to figure it out, but I found the backlight strip I installed a few months ago had failed.

When I change out LED strips I've been leaving the boards on back hooked up so once the panel is out I can still turn the TV on and see the backlights driven at full power. This is how I found the bad strip. The 30mA my LED tester puts out wasn't loading the LED's enough to make the weak link fail, it took the full power of the LED output on the PSU to make it show up. You just have to remember to pull the FFC's out of the T-Con so when the set is powered on there is no chance of shorting that signal to ground....and it goes BOOM.

These LED testers are great and will find bad LED's 99% of the time, but sometimes they don't have enough power to make some LED failures show up. It's just something to keep in mind when using one of these testers....they are a good answer but sometimes not a perfect one.

Used LED strips from Fleabay may also not be a perfect answer. The bottom line from now on is when backlights go out the best answer that leads to the least amount of future trouble is to buy them all new, install them new and keep the backlights turned down after.

Since the LED strip I installed 3 months ago is what failed I didn't charge him for the new strips or labor. I mean what kind of prick would I be to charge him for my mistake? I wouldn't do that to a friend...or anyone. If one can't be trusted with a little then they can't be trusted with a lot.

Any job worth doing is worth doing right. I believe new LED strips are the way to go when originals fail.

[petehall347]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

i have read manuals that say replace them all at the same time . makes sense but if replacing one strip in a low value set saves the set for a year or two when its value is surely going to be scrap then why not ?

[budm]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

A few months ago I traded an LG 50UH5530 for services from a friend of mine. It had the single backlight logo flash then no picture at start-up. The diagnostic led to the replacement of one LED strip, sourced from fleabay and out of a new freight damaged TV.

Fast forward to this weekend....when my friend tells me the backlights went out again, same backlight logo flash then no picture. Based on his description and to save him time I went ahead and pre-ordered all new backlight strips from ShopJimmy.

So last night I went and got the TV, opened it up, pulled the panel and checked each backlight strip with the LED tester. I was puzzled when all the strips lit up and tested at about the same parameters.

It took me a bit to figure it out, but I found the backlight strip I installed a few months ago had failed.

When I change out LED strips I've been leaving the boards on back hooked up so once the panel is out I can still turn the TV on and see the backlights driven at full power. This is how I found the bad strip. The 30mA my LED tester puts out wasn't loading the LED's enough to make the weak link fail, it took the full power of the LED output on the PSU to make it show up. You just have to remember to pull the FFC's out of the T-Con so when the set is powered on there is no chance of shorting that signal to ground....and it goes BOOM.

These LED testers are great and will find bad LED's 99% of the time, but sometimes they don't have enough power to make some LED failures show up. It's just something to keep in mind when using one of these testers....they are a good answer but sometimes not a perfect one.

Used LED strips from Fleabay may also not be a perfect answer. The bottom line from now on is when backlights go out the best answer that leads to the least amount of future trouble is to buy them all new, install them new and keep the backlights turned down after.

Since the LED strip I installed 3 months ago is what failed I didn't charge him for the new strips or labor. I mean what kind of prick would I be to charge him for my mistake? I wouldn't do that to a friend...or anyone. If one can't be trusted with a little then they can't be trusted with a lot.

Any job worth doing is worth doing right. I believe new LED strips are the way to go when originals fail.

Yep, you just learn something about the weak point of the LED tester, it is good for telling you if it has open circuit or not.
The thing is, why did the new LED strip fail already, is it used LED strip?

[DXseekerMO]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

i have read manuals that say replace them all at the same time . makes sense but if replacing one strip in a low value set saves the set for a year or two when its value is surely going to be scrap then why not ?

I see your point, and on lower value TV's I agree....I guess it's all about risk really. The way I feel about it, for every so many dollars someone spends on a TV it needs to last so long without any more trouble for it to be a good value to the buyer. On an LG 50" like this one with a local value around $300 I'd say the good value point is three years of further reliable service. On something like that I should have installed new backlights. On the other hand if this 50" Toshiba with a local value around $100 needed LED's I'd likely install single beads on existing strips if they were otherwise functionally OK and explain to the buyer why I did it that way.

Ultimately I don't want to sell or be known for selling junk. One dissatisfied person has an average of 250 people in their circle, and that's a heckuva lot of folks who could hear about it. I'd rather take the safe route and satisfy the buyer than entrust my reputation to the cheapest parts on fleabay. Believe me I've had to humble myself, keep my mouth shut and go the extra mile. Most people are reasonable, but sometimes this is what it takes. I don't mind....there isn't a thing wrong with humble.

Yep, you just learn something about the weak point of the LED tester, it is good for telling you if it has open circuit or not.
The thing is, why did the new LED strip fail already, is it used LED strip?

Yes it was used, allegedly from a new freight damaged TV. Once I got the backlights in I checked and it seems voltage/amps from the PSU are within range. I still had the other LED strip that came with the one that failed, once I put it in the backlights came on OK. I put my sunglasses on and looked at all the other LED's at two angles. They were evenly lit and the same color. I've noticed stressed LED's seem to light up dimmer and emit a different color than those that are good. All the other LED strips showed the same voltage and amps on the tester when I tested them, given it's limited ability.

The backlights were also turned all the way up. They didn't understand how backlight settings change with picture settings. I showed him that and how to apply backlight settings to all inputs.

I'm pretty sure the strip I put in caused the problem, that and the backlight setting.

[nomoresonys]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

Isn't it amazing how many items on "fleabay" come from "brand new tvs with cracked screens" me thinks some of them folks are being dishonest.

[budm]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

BTW, if you at the back side of the LED strips, do you see any brown tint where the LED are? If you do, that is the sign of LED have been running hot, you can also look through the LED LENS for sign of over heat also.

[DXseekerMO]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

Isn't it amazing how many items on "fleabay" come from "brand new tvs with cracked screens" me thinks some of them folks are being dishonest.

Methinks you are right!

BTW, if you at the back side of the LED strips, do you see any brown tint where the LED are? If you do, that is the sign of LED have been running hot, you can also look through the LED LENS for sign of over heat also.

There are no signs like that of overheating on the suspect strip or any of the others I removed.

[AFVet]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

Guys,
I am new here but not new to the electronics repair. I have the same model number LG TV and wished I had schematics of the power board. 50E6000-6L60N. I went through the trouble of checking the LED strips thinking that caused my problem, No video or sound, short flash when turning on 2 Red blinks. All the strips were good by my LED tester. Started to concentrate issue on Power Board after not reading any voltage on STB pin going from power board to main board.

Any recommendations or help appreciated.

[nomoresonys]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

may still be a backlight issue, testers are very good but have limitations, try unplug backlights and mainboard from poweboard then see if you have standby voltage and if its steady.

[neilc6]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

Flash of backlights is bad backlights. Replace them all with new. Led tester runs too low current to determine which ones are causing shutdown. On this model (UH series) both the backlights and tv shutdown with backlight error so you are not going to read any voltages in shutdown mode.

[truep]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

I always tell people to turn the backlights down to 75-80% to prevent led failure.

[handsworth]

Re: LG 50UH5530/5500 backlights test good with LED tester....BUT!

I just did 2 of the 50UH5530 tvs. 1 tv came on and played for days the other did not come on at all, just red led blinked. So one would think that the power board was bad since it would play for days at a time. All leds in both tvs tested good with a tester. The problem was that the leds were not under full power with the tester. Bought 2 sets of new leds and both tvs are fine now. So the tester will only tell bad, short or open circuits. BTW The place I got them from had mfg date of 3/2022, not the 2015 date we used to get