Samsung UN40F6300AF TV No Picture, Sound is working

[Wpbauer]

Hello! I have a Samsung UN40F6300AF LED TV that does not have a picture but does have sound. I do see the picture when I use a flashlight against the screen. From the web info I've read, I believe it is a backlight issue with either the power board (BN44-00645D) or possibly a bad LED light.

I'm not sure how to determine where the issue lies. I visually inspected the power board and don't see an issue. I tested the CNL802 LED outputs with the LEDs plugged in and unplugged, and show them below. I tested with a multimeter with the neg lead on the TV chassis and pos lead on the PIN (hope that's correct). The board diagram indicates CNL802 voltages of 136 and 182, but I'm not sure where those should be detected.

I also included pics of the TV configuration and boards.
Any guidance or suggestions would be greatly appreciated!!

CNL802 Unplugged:
PIN
1 NC 0V
2 NC 0V
3 0V
4 0V
5 0V
6 261V
7 NC 0V
8 NC 0V
9 0V
10 0V
11 0V
12 261V
13 NC 0V
14 NC 0V
15 0V
16 0V

CNL802 Plugged
PIN
1 NC 0V
2 NC 0V
3 0V
4 198V
5 198V
6 261V
7 NC 0V
8 NC 0V
9 0V
10 0V
11 0V
12 261V
13 NC 0V
14 NC 0V
15 0V
16 0V

[nomoresonys]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

With everything hooked up, do test #3 below on CNM803, don't forget to label the pins, so we know what they are.

[neilc6]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

Unplug the cable between the main board and power supply. Backlights should come on. If they dont, you likely have bad backlights.

[R_J]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

The voltages seem to indicate open led's in the panel, You should likely have voltage on 10 & 11 same as 4 & 5

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

With everything hooked up, do test #3 below on CNM803, don't forget to label the pins, so we know what they are.

Thanks for the quick response! This may be a stupid question, but I only can access 7 of the 14 pins of the connector that bridges from the power board to the main board. Short of turning the board over, not sure how to do that. I included a pic. Thanks.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

Unplug the cable between the main board and power supply. Backlights should come on. If they dont, you likely have bad backlights.

I unplugged the cable between the boards, and the backlights did not come on. Sounds like they are bad. Can you replace individual light strips or should I get a full set for the tv? Thanks.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

The voltages seem to indicate open led's in the panel, You should likely have voltage on 10 & 11 same as 4 & 5

Thanks for your reply. So backlights seem to be the problem here. I'll dismantle the tv to get to them. Can the light strips be tested individually to determine which one is bad?

[nomoresonys]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

Best practice is a full set because usually if you have one bad one others will fail very soon BUT if you don't mind tearing it back down you might save a few bucks with only one strip replacement. After you fix it be sure to turn your backlights down as far as you can tolerate, always avoid any vivid picture settings they drive the backlights to hard and kill them off prematurely.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

Best practice is a full set because usually if you have one bad one others will fail very soon BUT if you don't mind tearing it back down you might save a few bucks with only one strip replacement. After you fix it be sure to turn your backlights down as far as you can tolerate, always avoid any vivid picture settings they drive the backlights to hard and kill them off prematurely.

Thank you. I'll tear down the tv and see if I can get the lights ordered.

[nomoresonys]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

Let us know how you make out.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

I manged to get the TV apart and quickly discovered where the problem was. The first led light on the first strip burned out badly and actually fried the strip. It looks like it also may have damaged the strip that supplies power to the LED strips. Can someone tell me which set of numbers on the LED strips is the part number that I can use when ordering a set?

I think I should also order the strip that supplies power, and can I assume this is the part number - BN96-25336A?

I attached pics of the light strips and the power strip.

Thanks for any help you can offer!

[R_J]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

That looks like the correct number for the distribution board. it might be ok, clean it up, if the contacts on that end that connect to the strip are ok, it is likely just the led strip that needs to be replaced.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

That looks like the correct number for the distribution board. it might be ok, clean it up, if the contacts on that end that connect to the strip are ok, it is likely just the led strip that needs to be replaced.

Ok. What about the part number for the LED strips? I wasn't sure which set of numbers were actually the part number.

One other question, once I get the LED strips replaced, what is the best way to test them prior to putting the tv back together? Is it advisable to hook up the tv to power with it being apart?

[nomoresonys]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

BN96-25304A/BN96-25305A do you have those numbers on your strips? Yes good to test before putting everything back together to make sure they're working right.

[neilc6]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

https://www.shopjimmy.com/samsung-cy...face-board.htm

If you search the alternate part numbers, you can probably find for lower price on ebay or aliexpress.

You can do the backlight test on Samsungs with the panel removed before reassembling.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

BN96-25304A/BN96-25305A do you have those numbers on your strips? Yes good to test before putting everything back together to make sure they're working right.

Thanks so much for the reply. No, I don't have those on the LED strips. No BNxx numbers at all. I searched online with these codes that are on the strip and I found it on aliexpress.com:
2013SVS40F L 8 Rev1.9 130212 (left side)
2013SVS40F R 5 8 Rev1.9 130212 (right side).

The power strip (LED Interface SF) has number BN96-25336A. It has been a little harder to find a replacement for this.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

https://www.shopjimmy.com/samsung-cy...face-board.htm

If you search the alternate part numbers, you can probably find for lower price on ebay or aliexpress.

You can do the backlight test on Samsungs with the panel removed before reassembling.

Thank you! I did find the LED strips on aliexpress. I am working with shopjimmy to see if they have the LED Interface strip. Thanks for the confirmation that it's OK to test with power, since I don't have an LED tester.

This site is awesome.

[neilc6]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

That distribution strip I sometimes see sellers bundle with used strips on ebay. It is rare to see those damaged so would be difficult to find as a standalone part. I wouldn't salvage one out of a cracked TV. I would look for Aliexpress store Zhengbai or ZBLED. Same as a trusted seller I have used on ebay but about 10% less buying off Aliexpress.

[Wpbauer]

Re: Samsung UN40F6300AF TV No Picture, Sound is working

That distribution strip I sometimes see sellers bundle with used strips on ebay. It is rare to see those damaged so would be difficult to find as a standalone part. I wouldn't salvage one out of a cracked TV. I would look for Aliexpress store Zhengbai or ZBLED. Same as a trusted seller I have used on ebay but about 10% less buying off Aliexpress.

Thanks for the tip. I'll do some searches and see if I can come up with something. The folks at shopjimmy said they don't carry the distribution strip and said it could be hard to find.

Agian, I appreciate the help.