JVC LT-65N550A LED Issue

[RooTV]

Re: JVC LT-65N550A LED Issue

Interesting.

I tested each strip individually and there was one (half) strip that wouldn't light up at all. The rest were fine.

The interesting thing (to me anyway) was that if I reversed the probes on the dead strip, positive on negative etc, all the strips on the TV lit up, except the dead strip.

I tried the same thing on another strip and nothing happened? Is this because the dead strip is open or something?

[budm]

Re: JVC LT-65N550A LED Issue

Interesting.

I tested each strip individually and there was one (half) strip that wouldn't light up at all. The rest were fine.

The interesting thing (to me anyway) was that if I reversed the probes on the dead strip, positive on negative etc, all the strips on the TV lit up, except the dead strip.

I tried the same thing on another strip and nothing happened? Is this because the dead strip is open or something?

Can you shows us how you are testing them?

[RooTV]

Re: JVC LT-65N550A LED Issue

with the tv unplugged and the strips available, I found the + and - dots at the end of each strip and put the probes from the led tester on them. each strip, well half strip, lit up when it was good.

The tv is in pieces now so couldnt really photo it

[neilc6]

Re: JVC LT-65N550A LED Issue

Did you unplug the strips from the power supply before using the LED tester?

[RooTV]

Re: JVC LT-65N550A LED Issue

sorry I didnt have time to play around with it more, but I dont have a workshop or even an area I can work on these things.

As the photo shows, I live in a small place and have to wait till the other 3 people arent here before I can do anything on a fold up table in the small loungeroom.

I do what i can

[RooTV]

Re: JVC LT-65N550A LED Issue

Did you unplug the strips from the power supply before using the LED tester?

yes, all unplugged

[neilc6]

Re: JVC LT-65N550A LED Issue

What is the voltage on each of the two connectors measuring from the back? You can feed the connectors to the front to make it easier to observe.

[RooTV]

Re: JVC LT-65N550A LED Issue

Too late to check. Sorry.

[neilc6]

Re: JVC LT-65N550A LED Issue

I thought you wanted to learn how to use the LED tester to determine if you had bad LEDs by probing the back connector before taking apart the panel? You can reassemble the strips with the cables and connector. You don't need any boards for this test.

[RooTV]

Re: JVC LT-65N550A LED Issue

I do.

Before I stripped the tv down I did try putting the led tester probes on the connectors for the led's, with mixed results.

I mean that one of the connectors registered (I cant remember what) but the other one did not register at all, when I say that I mean it didnt change the led tester from what it registers normally.

I tried a few times but it didnt change.

Once I stripped the tv down and tested the strips themselves, and found one bad strip, I figured that was the issue and went ahead and pulled the rest apart.

Unfortunately where I am I dont have all day to work on it and I have to clean up before everyone else gets home.

I do want to learn, but I just have to really pick my times and this just wasnt the time.

Im sorry if you feel I have wasted your time or something, but I dont mean to come across as that.

[neilc6]

Re: JVC LT-65N550A LED Issue

Your results would have confirmed that one string was good (voltage and strips lighting up) and there was an open (no lights and no change in open voltage reading) in the second string. If one string had a short, it would have read lower voltage from the other one and would have lit up.

[RooTV]

Re: JVC LT-65N550A LED Issue

so because one connector didnt register, that shows you that it is bad?

[RooTV]

Re: JVC LT-65N550A LED Issue

I was expecting it to register but be a lower voltage than the good one.

I didnt remember what it registered coz I was looking for a difference.

[neilc6]

Re: JVC LT-65N550A LED Issue

LEDs typically fail short but can fail open circuit (less common). If you put your LED tester across an open circuit, there would be no change to the voltage reading and the LEDs won't light up. Would be the same as holding your probes up in the air. Same as measuring an open circuit with a multimeter.

[RooTV]

Re: JVC LT-65N550A LED Issue

yep, thats what it did.

Thanks for letting me know. I thought the probes just werent working or something

[neilc6]

Re: JVC LT-65N550A LED Issue

As an exercise, you should try to locate the open LED on the bad strip with your LED tester. If there aren't any test points, you will need to scrape the solder mask on one side of each LED to expose the copper. Since they are wired in series, the last LED typically has a long trace running along the edge to get back to the connector.

[RooTV]

Re: JVC LT-65N550A LED Issue

I think Ive seen that in a youtube video.

So you think it will just be one bad light in the strip?

Ive had others where it was just one or two that didnt work but didnt prevent the whole strip from working

[budm]

Re: JVC LT-65N550A LED Issue

If you still have the LED strips, I am sure we can walk you through step by step testing each LED strip and what to look for.

[RooTV]

Re: JVC LT-65N550A LED Issue

I do have them but the family is home now so will have to do that later

[neilc6]

Re: JVC LT-65N550A LED Issue

Some discussion in this thread.

https://www.badcaps.net/forum/showthread.php?t=83581