Samsung UN32F5500 with bad LEDs

[budm]

Got this one in today, the LED strings are connected in series, one had open LED, one has shorted LED. I bypassed them using 5 1N4007 in series to simulate LED, both LEDs are removed and replaced with 5-DIODE string.

[mmartell]

Re: Samsung UN32F5500 with bad LEDs

Good job bud, but why not just fit it with those leds from the D6000 ?

[budm]

Re: Samsung UN32F5500 with bad LEDs

I could not find them, I put them away some where.

[eklunge]

Re: Samsung UN32F5500 with bad LEDs

Good job, but how to determine the nos of 1N4007.

[mmartell]

Re: Samsung UN32F5500 with bad LEDs

Voltage drop 0.7v x 5 diodes roughly equals the voltage drop of the missing led at least the way I understand it..

[tom66]

Re: Samsung UN32F5500 with bad LEDs

Sigh, another Samsung with bad LEDs problem. Serious design flaw here.

[Dang]

Re: Samsung UN32F5500 with bad LEDs

This I need to do my self at some point, crappy Toshiba is suffering a similar fate.

[tom66]

Re: Samsung UN32F5500 with bad LEDs

I have to wonder, when two LEDs are already failed, is this really a fix. It seems like more will likely fail soon.

I see problems like this all the time due to cheap LEDs. If LEDs are designed and manufactured well, they last a very long time. But so many of them aren't -- there's a huge problem with fakes, too -- that we see early failures. I've seen LEDs fail intermittently, causing pulsing light sources (like a worn out fluro), I've seen colour mismatch after just hundreds of hours, I've seen package/bond failures, etc...

[tom thumb]

Re: Samsung UN32F5500 with bad LEDs

Interesting point tom66 I always tell my friends to stay away from LED tv's
and buy one with FL bulbs

[ammarben]

Re: Samsung UN32F5500 with bad LEDs

can we use white led 3.5v instead of 5 diodes?

[mmartell]

Re: Samsung UN32F5500 with bad LEDs

Yes

[budm]

Re: Samsung UN32F5500 with bad LEDs

I have to wonder, when two LEDs are already failed, is this really a fix. It seems like more will likely fail soon.

I see problems like this all the time due to cheap LEDs. If LEDs are designed and manufactured well, they last a very long time. But so many of them aren't -- there's a huge problem with fakes, too -- that we see early failures. I've seen LEDs fail intermittently, causing pulsing light sources (like a worn out fluro), I've seen colour mismatch after just hundreds of hours, I've seen package/bond failures, etc...

I am using that TV on my test bench for testing DVD player and such to see how long the TV will last before the other LEDs go out. I would not sell it due to the fact that the other LEDs will fail sooner or later. It is not worth the money to replace all the LEDs but for now it will extend the life of the TV for now, also not good to sell to the customer knowing that fact.

[martinm76uy]

Re: Samsung UN32F5500 with bad LEDs

Really thanks for your help. I have the same monitor with the same trouble. I have a single burned led. I replace it for other new one (another characteristics), but it burn out again. I will try to put the led and maybe a 1N4007 or two in series. And see what happen.

[budm]

Re: Samsung UN32F5500 with bad LEDs

The replacement LED may have lower current rating so it did not last.

[mrhappypants]

Re: Samsung UN32F5500 with bad LEDs

awesome post. after replacing my t-con board for no reason, testing/frying/fixing my inverter board, i found this post. cracked open and sure enough one stupid LED was all that was wrong. Replaced it with 5 series diodes and away she went. Not bad for a $30 tv off kijiji and oh ya 10 hours labor lol

[K2RJF]

Re: Samsung UN32F5500 with bad LEDs

Hi,
I have the same problem that was fixed by Samsung under warranty twice before but they refused the third time since it was out of warranty and don't recognize any "lemon law" service. Anyhow, I opened it up and probed around and after touching a wire jumper near the LED connector with a DVM probe the lights all lit. I watched it for about a half hour but started smelling a burning odor and then the LEDs went out. Since all the LEDs were working I thought that the PS board was bad so I orderd another. Replacing the board did not fix the problem so I opened up the LED panel and found one LED burned (the dome even fell off when I touched it). I pulled the strip out and saw some discoloration on 2 or 3 other LEDs. I started to test each LED but the PCB wiring seems strange and there are 3 pins on each LED (maybe they are just mounting points). The coating is tough and tried using a pin to push through but its hard to make contact. It looks like BUDM scraped away the coating and in his picture he put diodes across an area to the left of the open diode ... another reason to understand the pcb wiring. Has anyone tried putting a resistor across the terminals of one strip to simulate the voltage drop in order to test out the remaining LED strings? I appreciate any help to get this set working. Thanks.

[caphair]

Re: Samsung UN32F5500 with bad LEDs

I don't think a resistor would work unless it was set up as a voltage divide network, I assume it'd limit current to the LED before it but wouldn't drop voltage overall to the string.

I'm curious why those LEDs have three points? Merely for mounting?

[jts1957]

Re: Samsung UN32F5500 with bad LEDs

'Diode' has TWO solder joints.
'Lens' has THREE points securing.

[freakaftr8]

Re: Samsung UN32F5500 with bad LEDs

I just cracked open a UN75F7100 does the top LEDs, the top 6 strips on the top side were out. It uses the same LED backlighting and there's 12 horizontal strips in all and they attach in 4 different places across one strip as there are four separate strips are connected together in series across the panel. The beginning of the 6 rows of strips for the power connector is had four shorted LEDs. Found it on eBay that I need and its on its way here. I cannot sell this TV due to the fact that I'm worried others will fail prematurely. Oddly I think someone has swapped out boards because the timer says it is only two hours on the panel. This is not true the guy told me it failed a year after ownership so someone must have replaced the main board and the power supply because of the power supply was missing two screws. Here's what the inside of a 75 inch backlit LED Samsung looks like

[freakaftr8]

Re: Samsung UN32F5500 with bad LEDs

And some pics