ue46d8000 power cycling, bottom LED issue

[Bobbydazzler77]

It turns on and sometimes it will stay on for a few minutes and I can see the smarthub and play a movie from a USB stick for a few minutes.
Sometimes it cycles constantly we just the samsung logo flashing up.
I pulled the capacitors off the power board and and checked them and they are fine. I have checked for dry joints and unable to find any.
Originally I though the main IC might be bad sdp1002 on the main board as it gets quite hot but following advice from another thread I diconnected the main board
and shorted pins 3 and 4 and the panel lights up and cycles constantly.
I tested the voltages on the main plug and they look OK.

I removed the screen and inspected the led (side light led strips). One was loose I attempted to solder it back (hot air) on and failed so tried to jumper the ledout using a thin piece of wire.
When I power the TV I noticed that the bottom half of the LED's are not powerng up on both sides.
I tested the LED's in diode mode and they all lit up.
I am a noob and not sure what's going on!














Main Plug Reading


1-5.3V

3-4.8v
5-GND
7-12.8v
9-12.8v
11-12v (keeps dropping and rising)
13-12v
15-GND
17-5.3 (keeps dropping and rising)
19- 5.3v

10-13v
12-4.73
18-5.3v
20-3.4v

Any knowledge /help appreciated
Thanks

[R_J]

Re: ue46d8000 power cycling, bottom LED issue

The problem is with the bad led. you can NOT just jumper it out. the power supply will go into protection.
If you have not damaged the led or the board yet, you need to apply new flux to the led and the board so the solder will reflow properly

[Bobbydazzler77]

Re: ue46d8000 power cycling, bottom LED issue

The problem is with the bad led. you can NOT just jumper it out. the power supply will go into protection.
If you have not damaged the led or the board yet, you need to apply new flux to the led and the board so the solder will reflow properly

Yeah I will give it another go. I appled new flux and lead solder but was worried I was going damage the board.
So the led's only lighting half up is typical protection behaviour. One faulty LED will do this? Excuse my ignorance! If I can't fix it I will try and get a replacement led side strip.

Thanks.

[R_J]

Re: ue46d8000 power cycling, bottom LED issue

The power supply led driver monitors over and under voltage as well as current, so it does not take much of a change to go into protection.

[Bobbydazzler77]

Re: ue46d8000 power cycling, bottom LED issue

So I have ripped the board a little and hope I can repair it and solder another LED on.
I have continuity from + on D2 to the edge D1 so I can solder another LED onto the - of the new LED and keep the series going?
What will I do with the + on the last LED?

I am looking for 5630 smd led is that right? The one I saw on Aliexpress had a different anode and cathode connection but I was thinking as long as the driver can measure the correct power the TV will work even if it's not pretty!

Thanks

[R_J]

Re: ue46d8000 power cycling, bottom LED issue

You destroyed the traces and heat dissipation contact for the led. You need a new led strip. Where did that large solder area for D1 come from?

[Bobbydazzler77]

Re: ue46d8000 power cycling, bottom LED issue

The shiney bit for D1 is what was under the trace . The heat dissipation must be that black covering? That will glue back down. So it's impossible to repair the strip. I'm not sure the TV is worth the cost of new led bars, you have to buy x2. I understand it would be deemed a sub standard repair but its my TV and just a hobby to learn a bit.

One of the traces would have connected the + of d2 to negative of D1 led right? so where would the other trace go? Any ideas.
If I can prove the TV works buy repairing the board then I might be inclined to buy a set of led bars and repair properly.

Thanks

[nomoresonys]

Re: ue46d8000 power cycling, bottom LED issue

looks like a mess, best to replace all backlights, prolly the only problem, they shouldn't be too much on ebay, just go with a seller with good feedback.

[Bobbydazzler77]

Re: ue46d8000 power cycling, bottom LED issue

How do people go about repairing these bars? They are quite thick aluminium so can you use hot air station on them or do you use a fine tip iron to try and get the legs on the LEDS? The only other way would be to heat the whole bar up and pluck off with tweezers maybe?

Also if I was to try and buy some of these LEDS what would I look for? I'm not sure the 5630 is right?

Thanks