Sony KDL-46NX720 4 Blink error (with pictures)

[icethecold]

Hey Guys,

First time posting, my problem is with a Sony Bravia KDL-46NX720.

Problem:
The TV powers on for a few seconds seems to work fine (sound/picture/backlight/etc), then the whole display turns off and what I believe is the standby light turns on(Red LED) and blinks 4 times.

I found a post by user tibimakai in this thread that seems to describe the exact same issue. I purchased a new LD board (ST4055YL-S01) as was the described fix from ebay, and I still have the same issue.

Does anyone have a clue what to do about this? I don't want to just throw parts at it and hope it works. I'm not too familiar with TV repair, but I have a background in DC electronics and could do some diagnostics if anyone had suggestions.

I have also tried a factory reset, which didn't seem to make a difference. (Process: While TV is on, point remote and hold up arrow, press and release the power on the panel. TV will turn off then back on, release the up arrow) It did seem to perform the factory reset, but that doesn't fix the issue.

Here are some pictures:
https://drive.google.com/folderview?...Ws&usp=sharing

Thanks,
Sean

[zomi]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Need some clearer pics of the psu

also read here https://www.badcaps.net/forum/showthread.php?t=48346

[tibimakai]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Did you test those points first, on the "bad" board? My TV still works great, I'm watching it now.
Maybe, you have bad LED.

[icethecold]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Need some clearer pics of the psu

also read here https://www.badcaps.net/forum/showthread.php?t=48346

Hey zomi,

Thanks for the quick reply. I uploaded some better pictures of the PSU board in the google drive link.

zomi & tibimakai,

I did not test the points, I guess I was just hoping that board would solve the issue. To test the points, I should just test the voltage between that point and ground?. The thread zomi linked to discussed bad LEDs, would the picture be so clear when the TV turns on if the LED strips are bad?

Thanks again for the quick replies! I'm off to bed for the night, I'll see what I can do tomorrow.

-Sean

[zomi]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

bad led would appear as in the pic attached.

[zomi]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

https://www.badcaps.net/forum/showpo...5&postcount=14

[zomi]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

On the circled connectors are any of these labelled

BL-err

If u have bl error wire
You can gorund this to bypass the error and see what happens..

[icethecold]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Alright, I grounded BL-ERR, I attached a better picture of which pin it was and how I grounded it, though it wasn't on either of the connectors you circled.

Here is a video of what happened also:
https://drive.google.com/open?id=0Bw...nVGdFcyc2tSRDg

Basically it turned on like normal with sound, sound disappeared before the picture (also normal), then the screen goes blank (also normal), but the TV stays on and does not produce the 4 blink error code. So what does this tell me?

I also tested all of the fail test points on the LD board. All the test points read 2.82V-2.83V when the screen was lit and 0.077V-0.078V after the screen goes dark.

Also, I'll start using the bad caps file attachments for historical purposes, so in case the links to my google drive get broken, people can still see what the discussion is all about.

Thanks again for all the help so far guys.

[budm]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Service manuals.
http://elektrotanya.com/sony_kdl-40n.../download.html
There are 4 LED strings, so it is either one or more of the LED strings are bad or bad LD board.
Check the output Voltage of the LED string feeder before the backlights go out, you will have to do it four times (turn the TV on and off four times and monitor each pin to see which one reads out of place).

[zomi]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

My hunch is bad ld board. in this case the power supply

but you need to rule out the leds first..

[zomi]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Ps normally to ground the error wire
you remove it from the connector and take it out of the circuit.

[icethecold]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

<snip>
There are 4 LED strings, so it is either one or more of the LED strings are bad or bad LD board.
Check the output Voltage of the LED string feeder before the backlights go out, you will have to do it four times (turn the TV on and off four times and monitor each pin to see which one reads out of place).

My hunch is bad ld board. in this case the power supply

but you need to rule out the leds first..

I've replaced the LD board already with one from Ebay, I suppose it is possible I bought a bad board, but I kind of doubt it. Does that leave the LED strips then?
I've tried unplugging all the LED connectors one by one, they all seem to lighten and darken appropriately. Could it just be one individual LED out in a strip causing this issue?

Could someone elaborate on how to access LED strips and test them? From reading through the other threads, it sounds like I'll have to dismantle a lot behind the tv to access them, then take a multimeter to each LEDs contacts in diode mode for testing?

Thanks,
Sean

[zomi]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

No sorry I ment to write psu

On this one its combined unit

Where as on the 55" you have 2 power boards ..

And one of those is responsible for the the leds powering up as well
On the set you have Its combined into the psu as one unit and no sub board

To get to the leds you have to dismantle the lcd panel itself

[icethecold]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Hmm, alright. I'll take it apart tomorrow I guess. Thanks!

[tibimakai]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

If those points are all the same, then I would assume, that the LD board is good.
Pay very close attention, while the TV is on, if you see any darker spot at the edges of the screen, that would indicate the bad LED. As zomi pointed out above.

[kneeman]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

So we have the same problem, check my thread here.
Zomi gave me the same advice, read where I am at.

[kneeman]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

https://www.badcaps.net/forum/showth...t=48346&page=2

[icethecold]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Hey guys,

Sorry I vanished for about a month, I got caught up with some other projects and life. I started to disassemble the TV to get to the LED strips, but I chickened out and put it all back together, I'm not sure I have the proper space cleared for disassembling that right now. I don't think the LED strips are bad, the lighting looks very even while the TV is on. Does anyone have a suggestion on what the issue could be supposing the LED strips are good?

Thanks,
Sean

[icethecold]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Hmm, so I took off the psu board and tested a few components(apparently my multimeter doesn't do capacitance...) they do seem to give the correct values taking into account the components are generally hooked up in parallel, and are charging capacitors due to the meter being in ohm mode and the circuitry.

I think I've come to terms with spending money on this and just buying the boards(now that they are up on ebay)...could someone give me some reassurance, or some tests I could perform that would give me reassurance that even if I do buy a replacement board for every board in this tv, that it will eventually work?

Thanks,
Sean

[icethecold]

Re: Sony KDL-46NX720 4 Blink error (with pictures)

Hey guys,

I wanted to update you all, I got the TV working! Thanks so much to all of you for your help and feedback. It turns out that the first LD board I bought was not working.

I bought a new PSU board, and it luckily came with a new LD board too. I installed just the PSU board assuming the LD board I bought first was good. However the problem persisted. So I put in the new LD board that came with the PSU, and it all worked!

The first LD board came in bubble wrap, so I figure if the board did work before the seller shipped it, it might have been fried by ESD. The PSU and second LD board came in an anti-static bag.

I suppose it is possible that the original PSU board was faulty and fried both the original LD board, and the first LD board, but I kind of doubt that.

tl;dr: The problem was the LD board.

Edit: I couldn't find anything to make this thread as solved, maybe an administrator could do it.

Thanks again,
Sean