Seiki SE40FY27 Bad LED Strip help..

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

Oh, I also need the pictures of the LED connector to see how many wires it has on them and which pins are being used to verify the LEDs connections.
8 wires?

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

47uf 100v

So 80V is about right without the load.

[Louis82]

Re: Seiki SE40FY27 Bad LED Strip help..

I think they are parallel. I haven't opened the screen yet.

[Louis82]

Re: Seiki SE40FY27 Bad LED Strip help..

Yes there are 8 wires. Are we narrowing this down to a possible LED issue?

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

OK, tracing out the LED connector to the + leg of the 100V caps, you are correct, they are connected in parallel (all 4 Anode of each LED strings are connected the + leg of the cap).
So you did not see the backlights even flash on for second then since not all 4 strips can be all bad.

[Louis82]

Re: Seiki SE40FY27 Bad LED Strip help..

That doesn't sound good. Yes, backlights do not even flash.

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

I got to think about this a little bit, 4 LED strings connected in parallel and it has 80V applied for seconds but none light up for second.
I think we need to check the Cathode return for the LED strings which should be connected to current sensing resistors on the board close to the LED connector.
Check the resistance of those resistor R7, R8, R9, R10, R11 which are connected in parallel, I can see a diode connected in parallel with the resistors.
One end of those resistors are connected to GND.

[Louis82]

Re: Seiki SE40FY27 Bad LED Strip help..

Cathode is 0v for all 4 sets.

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

What resistance do you get on those parallel resistors?

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

Cathode is 0v for all 4 sets.

Did you monitor it with the probe connected to the Cathode when the TV is turned on and the Voltage rises up to 80V?

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

BTW, what is the P/N of that 8-PIN IC (PU2?) by the USB jack?

[Louis82]

Re: Seiki SE40FY27 Bad LED Strip help..

Hey Budm, So I decided to just open the screen (which I just learned that is not that difficult and screen is not as fragile as the ones that Element tvs use) and I found 12 brown/burned led's. I should have just done that from the beginning. I was just too afraid of breaking the screen.

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

Hey Budm, So I decided to just open the screen (which I just learned that is not that difficult and screen is not as fragile as the ones that Element tvs use) and I found 12 brown/burned led's. I should have just done that from the beginning. I was just too afraid of breaking the screen.

It is always best to verify that we do not have problem with the LED driver first since taking screen apart is kind of dangerous if we are not careful on the LCD panel.
Can you show the pictures of the LED assembly?
So bad LEDs on ALL 4 strips? That may explain why you have 0VDC on the Cathodes.
Driving LEDs in parallel is bad design, when one string goes open circuit, the other 3 strings will have more current flowing to them since it is constant current source driven to maintain the set current.

http://www.ledsmagazine.com/articles...-magazine.html

[Louis82]

Re: Seiki SE40FY27 Bad LED Strip help..

Yes. It was really bad. Every single strip had like 3 to 6 brown looking led's. Not worth it.
Sorry I can't provide picture. I closed that tv right after I saw the problem. I felt dumb making you troubleshoot the power board when problem were led's.

Thanks for you time Budm.

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

No problem, luckily not too many TVs use parallel drive for the LEDs.
I hope you have better luck with the SAMSUNG with C102 replacement but still clicking.

[beingsolvent]

Re: Seiki SE40FY27 Bad LED Strip help..

Great thread guys! I recently joined BadCaps because my SE40FY27 went black/dim while still carrying sound. I broke down the unit all the way to the diodes, and found a few strips were completely out. I wrote Seiki about replacement strips and they would not reply to my attempt to acquire them. Also betting that something on the board itself caused the lights to burn out. So I connected the strips individually to each output and they all act the same at all times. Anyhow having a hard time finding the strips, if you know of any shops that carry the LED strips all as one package could you please post the stores link? Thanks for your troubles guys.

[SLK001]

Re: Seiki SE40FY27 Bad LED Strip help..

Forget trying to find replacement strips. Get the LEDs and replace the bad ones. You will have to map out the PCB pads for the diodes to get the right ones. The Seikis that I have worked on had 3528 LEDs with the big pad as the CATHODE.

[ozzy214]

Re: Seiki SE40FY27 Bad LED Strip help..

I just took apart a Seiki last night and was going to put the strips on ebay. But I dont remeber what model I pulled them from. Got pictures of yours so I can compare?

[beingsolvent]

Re: Seiki SE40FY27 Bad LED Strip help..

Here are the led strips. Found them in China or Japan, forgot. Well here's the link.
http://www.sekaimon.com/us/163768/TV.../222079792397/

[budm]

Re: Seiki SE40FY27 Bad LED Strip help..

http://www.ebay.com/itm/like/2723426...&ul_noapp=true