CurtPalme.com Home Theater Forum

**Curt Palme**

So I inherited a very recent (2012 mode) Samsung 55" LED SMART TV from the recycler. It came out of a service center locally that's relatively reputable, I've dealt with them before, and the note on the set read 'bad panel', meaning LCD panel.

Symptom was that the LCD screen isn't cracked, displays the opening screen just fine, then the backlight flashes on and off, and the set dies. to me, that means that the LED light source was bad, the LCD screen was fine, and since it's impossible to get to the LED without spending an hour pulling the thing apart, I put the thing back in the box, and stored it outside against the garage. it's been sunny and overcast here, but last Weds it rained for 2 days. The Samsung box got wet, and fell over.

Being the lazy sort, I didn't bother picking the box up since it was all soggy anyway, and the set got rained on for 2-3 days. LAst night it dropped below freezing, and the raindrops froze on it.

For some stupid reason this morning, I got the urge to bring it back inside, to see if the LCD screen cracked with the thing falling on its back.

Still covered in water, I plugged the thing in. To my surprise, it's running FINE now, 5 hours after I powered it up. Go figure!

I can't sell this, but it's sure going to look good on my bedroom wall! I think I need another Irule system now.. Very Happy

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

You know, I would be more inclined to think that maybe the falling over helped the issue more then the rain but moisture can also do strange things. I would think that after at least 5 hours it would be all dried out though.

I hear so many guys claim a bad panel and when I hear the reason for their conclusion I am usually not convinced. As much as most people would like to think that repair techs must be correct when they tell them their set is not repairable, it is not always the case. I use to take stuff from local repair shops all the time that was left as non repairable and laugh at how simple the repair sometimes was.

**Curt Palme** · Posted: Sun Feb 02, 2014 12:36 am Post subject:

You know, that could be correct, never thought of that.

Also, what was interesting is that even though it's an LED TV, the wires between the panel and the light power source seem awfully thick and HV. I haven't done any reading on the newish LED light sources, but do they run on high voltage like the old fluorescent lights did?

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Well I have not had an LED for repair yet but from what other techs have said the led driver outputs anywhere from 200 to 600 volts. But it's DC. So it has some kick. CCFL is usually AC but at much higher voltage and less current.

I am really trying to avoid flat panel repair anymore. They are so cheap it is almost not worth the time unless it was free. Like you, a quick check of the PS and maybe a glance around and probe a few voltages and then that's it.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

I guess it depends on how many LEDs are to be driven. This is an edge lit tv so not a lot of LED's and is pretty self explanatory. 63v based on block size. I would guess the larger the block size the higher the voltage. Then current is calculated.

HD-DAVE · Joined: 16 Feb 2007 Posts: 225 Location: Delta, BC

Mac is on the money as usual - the backlights in these LED sets are just like the LED christmas lights; dozens of the damn things in series - xmas light led strings seeing 120 volts AC half wave rectified so they are turning on/off at 60 cycles. I am looking forward to when i scrounge my first dead LED set to open it up and see how its constructed. As for your set Curt I bet there was some wiring/build fault or wave solder blob that worked at first then raised its ugly head after a few hundred hours were on it... like a time bomb ...as a short in the backlight or its driver; when it started up the short caused an OVP or OCP to shut the PS down.... and when it fell over the jarring caused the short to be cleared ?!

**Curt Palme** · Posted: Wed Feb 05, 2014 6:26 am Post subject:

Well, it's still running fine so far. What I did see is that the upper right corner is slightly dimmer than the rest of the set. not bothersome, but to the point where I can't sell it, so I'll keep it. Now I just need to find the proper remote for it, the $3.00 universal won't let me do anything more than get to the internet access page, but I can't navigate it.

**AnalogRocks** · Posted: Wed Feb 05, 2014 6:32 am Post subject: