Samsung led tv UN55D7000LF power cycles on & off

[Rick7621]

I have a samsung led tv model number UN55D7000LF when I plug it into the outlet it power cycles on & off, the smart screen comes on & it shuts right back off & just keeps going over & over again. I've read every forum on here for the past two weeks I could find that was related to this TV & or the power supply tried a couple different things but non of them work. It was all a waste of time since the volt readings I took when I started is right where I'm still at here are the reading off the power supply on the 3 different connectors hopefully one of you guy's can help me out. I'm thinking the problem could be in the led lights cause of the readings i'm getting but I don't want to take the T.V. apart if I don't have to. Kinda hoping it's just a bad power supply.
So the only thing that stopped this cycling is when I unplugged the power supply from the main board. These readings are from the power supply unplugged from the main board. Also got you guy's pictures of the two boards and everything together.
Power supply number is BN44-00428A
Also no back lights when the main is unplugged from the power supply.

CNL802A
1. L2+ 0
2. L6+ 56
3. L2- 0
4. L6- 23
5. L1+ 0
6. L5+ 23
7. L1- 0
8. L5- 0
9. BLANK
10. BLANK
11. L8+ 33-45
12. L4+ 33-45
13. L8- 3-15
14. L4- 3-15
15. L7+ 23
16. L3+ 23
17. L7- 0
18. L3- 0
19.
20.
21.
22.

CNL802B
1. R7+ 124
2. R3+ 124
3. R7- 90
4. R3- 90
5. R8+ 90
6. R4+ 90
7. R8- 55.9
8. R4- 55.9
9. BLANK
10. BLANK
11. R1+ 124
12. R5+ 124
13. R1- 0
14. R5- 90
15. R2+ 0
16. R6+ 90
17 R2- 0
18 R6- 56

CNM803
1. OD LEVEL 5.1 1.2-5
2. P_DIM 4 0
3. OD ON/OFF 4.9 1.2-4
4. P_DIM 3 0
5. GND
6. P_DIM 2 0
7. B13V 12.6 1.2-10
8. P_DIM 1 0
9. B13V 12.6 1.2-10
10. B13V 12 1-10
11. VAMP 16.9 .9-13
12. BLU ON/OFF 4.5 1.1-4
13. VAMP 16.9 1-13
14. GND
15. GND
16. GND
17. B5V 5.2 1.3-5.2
18. A5V 5.2 stays the same
19. B5V 5.2 1.2-4.8
20. POWER ON/OFF 3.0 stays the same
21. N.C.
22. N.C.
Now on CNM803 on the right is readings I get after the power supply is plugged into the main board for a minute then unplugged last this way for about 2-5 minutes then goes back to regular readings. I also get these readings sometimes right when I plug in the power supply for the first time even without plugging it into the main board. I don't know if the LED light strip is shorted out that I'm not getting readings from & that's causing these off readings or if its just a power supply issue causing the whole thing. This issue also changes the power going into the led drive system from 124 to 109-115 then also goes back to 124.
Any input from here would be nice this is where I get lost & can't find a schematic to even check anything besides what the board tells me what some are supposed to read.

[budm]

Samsung led tv UN55D7000LF power cycles on & off

Here is the fast track. Do the backlights come on and stay when you do the force on test per fast track?
https://www.badcaps.net/forum/showth...ht=BN44-00428A

[Rick7621]

Re: Samsung led tv UN55D7000LF power cycles on & off

No they don't come on at all. No flash or anything from them.
I seen in all the forums I read about this tv and problems with the power supply that you were in everyone. Do the readings im getting seem right to you?

[budm]

Re: Samsung led tv UN55D7000LF power cycles on & off

The LED supply Voltages do not look right.
Will the TV cycle ON and OFF if the LED connectors are not in place?

[Rick7621]

Re: Samsung led tv UN55D7000LF power cycles on & off

Yes it still does even without them connected.

[Andrew F. Ali]

Re: Samsung led tv UN55D7000LF power cycles on & off

Looks to me like you have LED backlights failure.

[dick_barton]

Re: Samsung led tv UN55D7000LF power cycles on & off

Have you tried the solder fix as in an earlier thread on this PSU
https://www.badcaps.net/forum/showth...t=33767&page=2

Edit
You may also need to read SCN_0001.pdf also in that thread to turn on the backlights with the mainboard disconnected.

[Rick7621]

Re: Samsung led tv UN55D7000LF power cycles on & off

Thats what I was thinking to cause of the readings im getting on cnl802b

11. 124
13. 0
15. 0
17. 0
shouldn't 13 & 15 be 90v and 17 be 56v like the other sets?
So that would mean there's a problem in that set of leds right?

[Rick7621]

Re: Samsung led tv UN55D7000LF power cycles on & off

Yes I went thru that whole forum it's like every forum I read stops right where i'm at with no answer. I'm really thinking this led drive is my problem I just don't understand it completely but everything I have read tells me this is not right and may cause the tv not to power up. I have 124v going in but nothing on the other 3 lines coming back 13, 15, 17 on cnl802b they run next to the 124v. When I plug the main board in the voltage goes up like its supposed to on all 4 of these wires sending power into the led but the tv shuts right back off. The only thing I see not working right would be that one line of LEDs

[dskall]

Re: Samsung led tv UN55D7000LF power cycles on & off

(When I plug the main board in the voltage goes up like its supposed to on all 4 of these wires sending power into the led but the tv shuts right back off.)
So your getting voltages on each when you first power on?

[Rick7621]

Re: Samsung led tv UN55D7000LF power cycles on & off

I get voltage to each of the four when the main board is not plugged in and the backlights dont come on the voltage then is 124. when I plug the main board in the voltage goes up on all 4 but then the PS starts to cycle.

Yes I get voltage to all four when it first comes on but cycles always.

[Rick7621]

Re: Samsung led tv UN55D7000LF power cycles on & off

I know it's been a couple weeks but I finally got time to take the tv apart & found the led back light boards there are actual LEDs that have broke off the board mostly the top 4 inches on both sides of the boards. There's only two boards holding LED light's one on each side left & right. I'm not the best when it comes to leds like this but that would cause the issue i'm having? I do know that it is a problem just don't want to spend the money on these LED boards & have the same issue still.

[dskall]

Re: Samsung led tv UN55D7000LF power cycles on & off

Pictures might help to see problem

[Moreno83]

Re: Samsung led tv UN55D7000LF power cycles on & off

Leeds fail because most of the times people have the backlight option in the menu on full.

Put the backlight on 12 / 13. For example , if the backlight goes to 20 max , put it on 12.
The leds will last longer and the picture looks better also.

[mrdiy88]

Re: Samsung led tv UN55D7000LF power cycles on & off

Sorry to bump the thread here guys but I have a similar issue. The TV is a Samsung Smart UE55D8000YU

The Issue: The TV clicks and comes on with the smart TV logo showing, then will go off, and on, then off etc. Sometimes it will stay on for 5 minutes or more.

What I have done so far! Please bear with me, I'm new to looking at TV's so things may sound silly to you lol.

1) I have disconnected the main board from the power supply board expecting that the LEDs would remain lit. No LEDs stay lit but the on off cycling stops.

2) The TV was on long enough for me to flash the firmware to the latest version via USB from Samsungs website. (Didn't sort but wanted to try just in case)

3) Have changed all auto off settings (although I know now its nothing to do with settings)

4) Checked solder joints, no cold joints and all looks good across the board. All capacitors look good (visually) no spill etc.

Board Info: The main board is: BN94-04313T

PS Board is: PD55B2_BSM BN44-00428A

Also the forum will not allow me to create a new thread I have followed the welcome email to a t but to no avail hence why I am here on this thread (sorry)

Any help would be appreciated, I was tempted to purchase a power supply board to swap it over but scared in case it isnt that.

Also guys (bare with me) how do I go about testing the voltages that there should be at the pins. I have standard voltmeter but not sure of the method so any guidance would be highly valued.

Thanks
Ry

[dskall]

Re: Samsung led tv UN55D7000LF power cycles on & off

Check post #2

[mrdiy88]

Re: Samsung led tv UN55D7000LF power cycles on & off

Hi Thanks for this,

As per the fast track, when I remove the main board no led lights show. The TV was working yesterday and stayed on long enough for me to flash the latest firmware and it stayed on until I started to play a movie then it started cycling again. Logo on screen then off...repeat.

When I remove the main board the cycling stops and power supply comes on.

I am currently taking readings and noting these down.

Here are a few images of my TV.

Thank you for any help, it is much appreciated and I must say I am enjoying this challenge (might not be saying that at the end though).

Is it worth while me looking into resetting the TV or would that not be the correct next step?