Replacement LED question - what will work?

[Kg74]

Hello: Need some help on replacement LEDs for my Westinghouse LD-3255VX. Bothered by a bright spot or dark spot on the panel, I decided to pull it apart and test every LED. A group of four or so, corresponding to the area that had uneven brightness, tested different than the others. Both with the VOM Diode mode, showing some at .853 and in brightness. Under power, visually, one only glows a single spot rather than both (plus some are dimmer).

My question is what type of replacement LED should I source. I am having no luck finding any data or specs. I read some of Budm's posts and they were very helpful, but left me a tad confused.

Here is what I know. The TV has two LED strips of 40 LEDs. The marking, I assume is the part number, reads “TV-31.5 L” for left side and “TV-31.5 R” for right side. I am only having issues on the left side. This makes sense as this was the side that had the MC34844 failure. The strips are branded Kenmos. On the other end of the LED, near the connector, there are two markings 94V-0 and 1002. These markings can be seen in my photos. The aluminum strip measures 5.15mm wide.

When I put a VOM to a single LED, in Diode Mode, it does not light and most of the LEDs read .792 v. When I try to power a single LED with a power supply it will just glow purple/blue at 4.7 v, and pure white at 6v. (I have done this test with scrap LEDs that are in the 2-3v range and they light dim with my VOW in Diode Mode).

With the LED strip laying flat with the numbers on top, connector end on left and LED40 on right, the cathode marking is on the right lower corner. The back of the LED has three pads, anode, cathode and center rectangle (which I assume is just a solder pad as when testing with VOM I get nothing to the other pads). For measurements I get 56 x 30 x .9-1mm (the thickness seems to vary).

Backing up, if I use the 94v marking and divide by 40 I get 2.35v, but if I apply this voltage to a single LED it will not light. So I think I have 6v LEDs and the 94v is meaningless. I took these ideas from Budm's posts, most likely incorrectly.

This TV is a labor of boredom and will power. I am willing to change out all 80 LEDs with a suitable substitute if need be, or preferably just the 4-5 that are bad. Looking at pricing on what could be suitable 5630 6v substitutes – replacing all 80 appears cost prohibitive. If I do just 4-5 with a different LED may leave me with strange results.

Any ideas or words of wisdom? I did order a used set of strips, but the pictures of them show some are brown. I can just swap those over, but if a better alternative which allows me to do all 80 for under $15 is available I would go that route. Plus I want to learn how this all works. Thanks

[budm]

Re: Replacement LED question - what will work?

I do not know what the replacement LED is. You probably can get the 5630 SMD LED from Aliexpress.
Per you post: "most of the LEDs read .792 v' that is the forward Voltage reading of the protection diode which is connected in anti-parallel with the 6V rated LED, your VOM is not capable of putting out enough Voltage to forward bias on the LED when you connect the VOM in the correct polarity to the LED.
94V-0 is the UL compliance of the PCB flammability rating.
If you are going to replace the strip, you should verify that the strips are made for the LCD panel model number.
https://www.aliexpress.com/wholesale...+led+backlight

You can also check post #2 on this thread: https://www.badcaps.net/forum/showth...light=5630+led

[Kg74]

Re: Replacement LED question - what will work?

Thanks budm. I looked through all the listings and could not find anything that looked the same. If you would answer some additional questions I would appreciate it.

1) What is the difference between a 3v and 6v 5630?
2) How many LEDs are within the LED? I read that there are two in some of them. Looking at mine it looks like it has two - is that the difference between 3V and 6V variants?
3) Generally what color does one look for - I saw mention of 5600k?
4) What about wattage? Can one mix and match here or do they all need to be the same. Expanding if they are all replaced with a different wattage what is the impact on the TV? What if only a few of different wattage are changed?

At this point I think I will just swap LEDs off the used strips I bought and should arrive Monday or Tuesday. I will test each one with the VOM and power supply picking out the best ones for the transplant.

I still want to try and figure this out so any additional information would be great.