Samsung TV keeps blowing LEDs. What to look for ?
Good day folks. I'm in a bit of predicament here and would like some thoughts: I've got what seems a new-generation Samsung TV which keeps blowing the backlight LEDs (I shall post pictures and the exact model tomorrow, but for now I'll hopefully receive some general guidelines so I don't mess it up even more). LONG STORY WARNING 
The scenario seemed very simple: it's your typical "sound but no picture" deal, so I opened up the panel like always, got to the LEDs and quickly noticed something indeed went very wrong in there. Two LEDs must've gone out with quite the fireworks, because part of the traces is absolutely charred and burnt to a crisp and the white reflector sheet that covers the strips has holes in it in those areas, as if putting a lighter up to the thing. The lens of one of them is completely black as well - definitely unusable (I shall post a picture of this as well). I thought I'd just be able to get away with just replacing the burnt LEDs, but upon popping the lens on one of them, I ran into trouble: this new generation of LEDs are TINY, unlike everything I've seen so far, so not only I didn't have them on hand, but it would also be impractical/impossible to replace them.
I moved on to finding and ordering whole strips then. With considerable effort, I was able to locate a set of 3 recovered from a similar TV. They aren't brand new in the box, but definitely not worn out either. Before installing them, I DID check the rest of the LEDs one by one like I always do just to rule it out and amazingly only the one with the black lens which went up in flames is busted - the other one which SEEMED dead, came on just fine (despite having a big friggin' hole in the trace...). I thought I'd replace just the strip with the charred LED (so I'd have the other 2 remaining if need be), so i did that, left the two original ones in place, plugged the set in and after turning on for a VERY brief moment, I heard a pop and saw a spark flying out of the newly installed strip and everything died......great
So like what the hell ? :| One thing that bugs me is that these strips also have a diode next to each LED and it is this diode which actually popped back there (it's completely obliterated - couldn't even find its remains, just the pads were left of it !). Haven't seen this setup before and it seems so stupid and useless...So now I was stuck and didn't know what to do: I certainly didn't want to try out another replacement strip, for fear it'd blow as well. I'm pretty sure it had something to do with that punctured trace on the strip I left in, but my meter did not register any shorts on any of the LEDs, and it certainly would've picked it up, since those diodes are reverse-biased in parallel with the LEDs, so if they were shorted, the meter would've told me so upon measuring the LED. I shall now attempt to mix and match the strips, hoping that it was a one-off incident and it was a bad diode there (I didn't check the strips once I got them, since I've never had issues with them).
Could something be going on with the PSU as well ? :| I've NEVER had LEDs failing because of the PSU, much less so on Sammies. Must admit I haven't done any in-depth measurements, but upon startup with no strips connected, I see around 120v on the rectifier diode after the small transformer, which should be slowly going down...can't recall if it does so or not. I shall measure more carefully, but for now: does this seem like a strip issue or a PSU issue ? Has anyone successfully repaired one of these newer sammies which (hopefully) match my description ? Am I gonna be a pioneer ?
The scenario seemed very simple: it's your typical "sound but no picture" deal, so I opened up the panel like always, got to the LEDs and quickly noticed something indeed went very wrong in there. Two LEDs must've gone out with quite the fireworks, because part of the traces is absolutely charred and burnt to a crisp and the white reflector sheet that covers the strips has holes in it in those areas, as if putting a lighter up to the thing. The lens of one of them is completely black as well - definitely unusable (I shall post a picture of this as well). I thought I'd just be able to get away with just replacing the burnt LEDs, but upon popping the lens on one of them, I ran into trouble: this new generation of LEDs are TINY, unlike everything I've seen so far, so not only I didn't have them on hand, but it would also be impractical/impossible to replace them.
I moved on to finding and ordering whole strips then. With considerable effort, I was able to locate a set of 3 recovered from a similar TV. They aren't brand new in the box, but definitely not worn out either. Before installing them, I DID check the rest of the LEDs one by one like I always do just to rule it out and amazingly only the one with the black lens which went up in flames is busted - the other one which SEEMED dead, came on just fine (despite having a big friggin' hole in the trace...). I thought I'd replace just the strip with the charred LED (so I'd have the other 2 remaining if need be), so i did that, left the two original ones in place, plugged the set in and after turning on for a VERY brief moment, I heard a pop and saw a spark flying out of the newly installed strip and everything died......great
So like what the hell ? :| One thing that bugs me is that these strips also have a diode next to each LED and it is this diode which actually popped back there (it's completely obliterated - couldn't even find its remains, just the pads were left of it !). Haven't seen this setup before and it seems so stupid and useless...So now I was stuck and didn't know what to do: I certainly didn't want to try out another replacement strip, for fear it'd blow as well. I'm pretty sure it had something to do with that punctured trace on the strip I left in, but my meter did not register any shorts on any of the LEDs, and it certainly would've picked it up, since those diodes are reverse-biased in parallel with the LEDs, so if they were shorted, the meter would've told me so upon measuring the LED. I shall now attempt to mix and match the strips, hoping that it was a one-off incident and it was a bad diode there (I didn't check the strips once I got them, since I've never had issues with them).
Could something be going on with the PSU as well ? :| I've NEVER had LEDs failing because of the PSU, much less so on Sammies. Must admit I haven't done any in-depth measurements, but upon startup with no strips connected, I see around 120v on the rectifier diode after the small transformer, which should be slowly going down...can't recall if it does so or not. I shall measure more carefully, but for now: does this seem like a strip issue or a PSU issue ? Has anyone successfully repaired one of these newer sammies which (hopefully) match my description ? Am I gonna be a pioneer ?
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