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Old 04-07-2020, 04:23 PM   #1
Trevtron
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Default Samsung UE65H8500 wet inverter board

This apparently 'dead' set was given to me to "have a look at" but the owner had already replaced it so wasn't much interested in getting it back. Nice!
Almost immediately after plugging it in I could hear the speakers popping quietly so presumed something was overloading the power supply causing it to trip.
After finding a large piece of foam for the bench (I didn't fancy laying a curved screen on a flat hard surface) I took the back off & looked for any suspect cap's etc. but there was noting obvious. Unplugging the inverter board appeared to bring the set to life, so out it came.
The solder side of the board appeared to be wet. Not 'water' wet, but more like that clear stuff you sometimes find if a battery has leaked. This seemed strange as it had been in my (dry) workshop for a good couple of weeks prior to me opening it up. I'd heard the the owner was a bit of a w*nker so I assumed someone had perhaps poured some beer or something down the back of it. There was visible corrosion damage around some of the transistors.
So a replacement board was duly ordered. When it arrived I made sure the insulating plastic sheet that sits between the board and the metal backplate of the display was completely cleaned of any residue. Fitted the replacement board & the set fired up first time. Joy! A 65" curvey for less than 30!!
So up to the living room it came, replacing an older but perfectly good 55" Sammy.
But it didn't last for long. About 10 days later it refused to start up again, this time I could clearly hear the mains relay clicking away as it tried & tripped.
So back onto the bench it came, same scenario again, inverter board disconnected and away it went. To my surprise the back of the board was soaking wet again with some horrible corrosion around one of the transistor legs. Unfortunately I'd disposed of the original board or I would have tried some swapseys. So another board is now on its way. However in the meantime I had taken out the black plastic sheet and cleaned it up and left it at the side of the bench. About a week later I happened to look at it and it's soaking wet again.
So. (A) What is that evil stuff oozing out of it and why?
And (B) Is it really necessary?
If it were a CFL inverter I'd be wary of high voltages arcing across to the aluminium backplate but this is a LED set with somewhat tamer voltages so I'm tempted to not bother with one.
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Old 04-07-2020, 07:33 PM   #2
ngth82
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Default Re: Samsung UE65H8500 wet inverter board

What does the insulator material feel like it's made of?

Rubber like materials tend to get "sticky" / "gooey" over time. (Although i've never seen insulators made out of anything else other than plastic sheets).

As an alternative, maybe double stick tape a pink ESD bag on the back side of the panel chassis to prevent any gross shorts between the board and the chassis?
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Old 04-08-2020, 02:16 AM   #3
Trevtron
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Default Re: Samsung UE65H8500 wet inverter board

It's definitely not that rubbery stuff that goes sticky, it's quite a firm card.
Good call re. ESD bag, it's just the sort of thing I don't throw away so I may have one kicking about somewhere.
I've just moved house/workshop so my stock of "things that might come in handy some day" is at an all time low right now - hence the binning of the old inverter board .
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Old 04-16-2020, 01:29 PM   #4
Trevtron
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Default Re: Samsung UE65H8500 wet inverter board

Update: Well the new board arrived, I fitted it along with an alternative insulating layer between it and the LCD backplate and the set fired up no problem.
I left it on most of the afternoon playing 4K Youtube videos before buttoning the back on hopefully for the last time.
Having already had it in my own living room, a unanymous decision was reached by the other half that it is too big!
A friend had expressed more than a passing interest in it so he took it away and rang me later on to tell me how thrilled he was with it.
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Old 04-16-2020, 03:40 PM   #5
ngth82
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Default Re: Samsung UE65H8500 wet inverter board

Thanks for the update!

Too bad -- a 65" TV would be fantastic i think

I have a 55" TV above our fire place as a Chromecast picture frame TV.
50" TVs else where in the house .
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Old 04-17-2020, 02:28 PM   #6
Trevtron
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Default Re: Samsung UE65H8500 wet inverter board

Got too excited too soon! Said friend took the set away, loved it then this happened:
https://www.badcaps.net/forum/showth...765#post955765
I call it the curse of leaving the workshop
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