Samsung UE32F5000 (UK model) with no display. Power supply is OK.

[flocko]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Now steep away from the tool box, turn down the back light sit back and enjoy. You got there in the end Flocko

[Chungalin]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

I've received one of these (Samsung UE32F5000AK, or UE32F5000AKXZT) with no backlight. I have 220VDC at LED power supply, so it seems that I'll have to open the panel and look for bad LED(s). I have a LG 24MN43D LED TV with broken LCD glass. With a bit of luck I'lle be able to get good LEDs from there. Will report progress.

Update: I've found 3 open LEDs and another one that reads a little higher than the others (under diode test, normally "770", and this one shows "805"). I'll try to replace all 4. They're covered with some kind of plastic lens.

[Chungalin]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Not so fast...

I’ve tested all them again with reverse polarity and all them but ONE faintly glow. I didn’t notice this glow before, because the room was very lit, but now with less light it’s clearly visible.

This brings me another thought: how could be possible that there were 3 open LED? They failed at the same time? Impossible! Since all 45 LED are in series, after one opens, there’s no chance for others to keep working and get open some time later.

So my conclusion is: there’s just one open, and perhaps 2 or 3 that show some wear and may fail sooner.

I’ve had the brilliant idea of replacing that LED with one scrapped from a cheap chinese LED light bulb. Well, it has worked... for a few seconds. The cheap LED has shorted, while the others still working. Same as puting a wire bridge...

I’ve discovered how hard is to unsolder these high power LED. I wonder how will I unsolder good LEDs from another panel and keep them usable. Hot air? Will they melt?

[ralphup]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Not so fast...

I’ve tested all them again with reverse polarity and all them but ONE faintly glow. I didn’t notice this glow before, because the room was very lit, but now with less light it’s clearly visible.

This brings me another thought: how could be possible that there were 3 open LED? They failed at the same time? Impossible! Since all 45 LED are in series, after one opens, there’s no chance for others to keep working and get open some time later.

So my conclusion is: there’s just one open, and perhaps 2 or 3 that show some wear and may fail sooner.

I’ve had the brilliant idea of replacing that LED with one scrapped from a cheap chinese LED light bulb. Well, it has worked... for a few seconds. The cheap LED has shorted, while the others still working. Same as puting a wire bridge...

I’ve discovered how hard is to unsolder these high power LED. I wonder how will I unsolder good LEDs from another panel and keep them usable. Hot air? Will they melt?

try looking at this vid:

https://www.youtube.com/watch?v=Bf5T2wwtydY

I did find some LEDS on Ebay but they werent the rigth colour / temp.

[budm]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Not so fast...

I've tested all them again with reverse polarity and all them but ONE faintly glow. I didn't notice this glow before, because the room was very lit, but now with less light it's clearly visible.

This brings me another thought: how could be possible that there were 3 open LED? They failed at the same time? Impossible! Since all 45 LED are in series, after one opens, there's no chance for others to keep working and get open some time later.

So my conclusion is: there's just one open, and perhaps 2 or 3 that show some wear and may fail sooner.

I've had the brilliant idea of replacing that LED with one scrapped from a cheap chinese LED light bulb. Well, it has worked... for a few seconds. The cheap LED has shorted, while the others still working. Same as puting a wire bridge...

I've discovered how hard is to unsolder these high power LED. I wonder how will I unsolder good LEDs from another panel and keep them usable. Hot air? Will they melt?

https://www.badcaps.net/forum/showthread.php?t=54202
This one has 38 LEDs in series, 12 are shorted, 2 are open.

[Chungalin]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

try looking at this vid:
https://www.youtube.com/watch?v=Bf5T2wwtydY

Thanks, good video.

I ordered two LED strips from AliExpress. Since I planned to use the "stacking" method (as explained by ReeceyBurger), I ordered those strips with best price/number of LEDs ratio, so I ended buying two 9 LED stripes (0.75€ per repair unit). There're others with same price but less LEDs per strip:

http://www.aliexpress.com/item//32640850145.html

Now I see there're other cheaper options. I'd try this lot of 5 strips with 10 LEDs, 0.48€ per unit:

http://www.aliexpress.com/item//32656826571.html

Well, after one month wait for the LED strips, I remove damaged LED, clean solder pads, put a piece of kapton tape over the soldering pads, apply thermal paste, cut a piece of replacement strip and solder with wires.

I think that some extra care has to be taken when cutting pieces of aluminium strip. Since copper tracks are closely printed over aluminium, I use a metal file to remove sharp irregular edges and prevent copper track from touching aluminium base in any way.

It works for a minute and darkness again. Why? Neighbor LED has shorted, and the next one doesn't test OK either. Replace these two and now it resists. I've lowered Backlight intensity from 12 to 8 (surprisingly, it wasn't set at maximum 20). Now I'm testing it before returning it to customer. I can't notice any color difference. In this sense, it's a success. My main concern is: how long will last remaining LEDs?

[mihu84]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Hello

I have the same problem with TV Samsung UE32F5000. Audio is works. No video, but I checked back lights, and it worked.

LCD panel or power supply for him is maybe damaged. Capacitators looks OK.
Could you tell me, where is problem?

Thank you very much for answer.

Sorry of my bad english.

[dick_barton]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Check the fuse on the Tcon for continuity
Check the voltages given on the Tcon
For example
VIN12V =
VGH =
VGL =
VCC3.3V =
VCC1.2V =

It appears as though these Tcon boards are troublesome.
https://www.badcaps.net/forum/showth...ighlight=runtk

[mihu84]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Thank you for fast answer. Fuse is OK.
Where I check whe voltages on Tcon?

Thank you

[dick_barton]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

The points are all marked on the Tcon and will be shiny copper pads.

[mihu84]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Do I understand this correctly?

IF yes, this are measured values.

VIN12V = 12.95V
VGH = 0.03V
VGL = 0V
VCC3.3=0.05V
VCC1.2=0V

I need change Tcon board?

[Chungalin]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Follow the link to the other thread that Dick has pointed out.

[dskall]

Re: Samsung UE32F5000 (UK model) with no display. Power supply is OK.

Do I understand this correctly?

IF yes, this are measured values.

VIN12V = 12.95V
VGH = 0.03V
VGL = 0V
VCC3.3=0.05V
VCC1.2=0V

I need change Tcon board?

Looks pretty dead. I kicked it but it didn't move