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Help with a dead Samsung 46" LED model (UN46C6300SFXZA)

post #1 of 19
9/29/12 at 12:48pm
Thread Starter 
Hi all,

A relative has given me a dead 46" LED-lit Samsung (UN46C6300SFXZA). He wasn't sure what exactly killed it. He had a service tech come by who may have assumed it to be a surge, as it was plugged directly into the wall.

It won't power on. If you hit power, the screen just remains black and you can hear a relay clicking off and on attempting to bring it up.

The tech gave him an estimate, and from what I can make of it, he tried replacing two boards, but stated that it would need a third, which he must not have had on hand. With all three plus service, the estimate was then too high to justify fixing it. From the receipt he left, it looks as if he brought the mainboard and power supply boards with him, so the T-Con is all that would have been left, though I'm not sure about how far into it he got.

According to a web post I found about a similar TV, if the T-Con board was at fault and its ribbon were then disconnected from the mainboard, the clicking should stop and the TV should power up. If not, there is likely a problem with the mainboard. Unfortunately, disconnecting the T-Con changed nothing here and it kept clicking.

Does that procedure sound valid for this particular model, and if so, where would I go from there? The post I saw went on to describe a way of simulating a "turn on" command by jumping some pins together, as well as checking for a standby voltage, but again, it was for a different model.

FWIW- All three boards look to be in perfect condition, as do all electrolytic caps on the power board. They're too high voltage for my ESR meter, but I'm guessing its not one of the simple Samsung cap failure deals. frown.gif

If anyone can offer any assistance on this, it would be much appreciated.

-Thanks!

George

PS- Don't ask me why the tech would estimate and bill him for three replacement boards after determining that the first two weren't the cause of it. It didn't make any sense to me either, but that's also why I'm not certain that he actually swapped in the first two or that the mainboard can definitely be ruled out as a culprit.
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post #2 of 19
10/2/12 at 2:09pm
Thread Starter 
Bump on this as a last resort. I may try to post to that web thing I found next.

Also, if anyone knows of a service manual archive or has a copy of the one for this set, please let me know.

-Thanks!
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post #3 of 19
10/3/12 at 10:57am
Thread Starter 
Post three (sorry).
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post #4 of 19
10/3/12 at 10:57am
Thread Starter 
Post four (sorry again)
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post #5 of 19
10/3/12 at 11:01am
Thread Starter 
Fifth post (and explanation)-

Apologies for that garbage. Someone had offered to help, and the forum software refused to let me reply to him, as I had reached a two PM maximum. I think if the post count is too low it figures I'm a bot or something.

Hoping five works.

If that's against a rule, feel free to delete the posts - and sorry again.

Take Care
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post #6 of 19
10/3/12 at 2:56pm
Since your set has been out of service, the following step doesn't apply, but may be useful to others.

First, the power supply and processor on the main board run 24/7 and the EPROM can get corrupted by spikes and surges. Try unplugging it from the AC outlet for about an hour to see if the TV will reset itself to factory settings.

The power supply has Standby 5vdc (this is a MUST have before anything else will work, when this voltage is not present, there will be no any indicator light on the front panel) which is always on the minute the TV is plugged into the AC outlet, so it is on 24/7 and that is why the power supply will fail even though you may use the a TV not very often. It will see all the voltage spikes and surges 24/7.

This 5vdc is used to power the Processor and the Infrared remote receiver module which will be waiting for the command from the remote control or from the power switch, when the Power on command is received, the Processor will send the turn on signal (3.3~5vdc) to the power supply module (PSON pin) to the switch on the main 5vdc for the rest of the logic and Tuner circuits, the sound amplifiers and for the T-CON board (interface board between the LCD panel), the Logic board) and the Back lights inverter board .

Main Logic board (It has Processor, Tuner, Sound Processor, Sources selector, Power amplifiers for speakers, interface port to the T-CON board for pictures).This logic board sends out the turn on signals (3.3~5vdc) to turn on the rest of the Power supply module (Switched & main 5vdc, 12~16vdc etc.), Backlight ON (if no back light on command then there is no back lights), Logic board supplies 5 or 12vdc to T-CON board B+ pin through switched transistor if T-CON board does not get the voltage from the logic board, you will get white/gray glowing screen without pictures, Back lights Dimming (PWM) control signal.

Long story short, if you have a multimeter, the very first thing to check is for Standby 5V and then to see if all of the other required voltages are present on the power supply board.

The power supply board for your UN46C6300SFXZA is here:

http://www.shopjimmy.com/samsung-bn44-00356a-power-supply.htm

Note: You can mouse over picture to zoom in.

The power supply board has at lest 3 fuses on it, first check that none of them have blown (opened up).

Then, check the voltages at the CNM801 power connector located at the top right of the PCB. The voltages and pin assignments for the CNM801 connector are silk screened on the PCB, to the left of the bar code sticker.

Good luck, that is a nice set and worth repairing.
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post #7 of 19
10/3/12 at 7:46pm
Thread Starter 
Thanks Thiao for all the info,

As mentioned, I've got someone helping me on it, but this stuff might save him a minute.

My power board appears to be a BN44-00356B rather than 'A'. The pinout labels were on the bottom. The fuses were something I looked at when I first opened it. They're all OK, and the standby circuit (from observation) seemed to be doing its thing. I get the red standby light while it's plugged in, and the IR & front panel power switches both respond, sending the relay into that clicking state. Nothing appears to be telling the backlights to come on, as the screen remains black through everything.

I'll have to rig up a safe way to check some of those mainboard pins without zapping anything. I'm guessing much of it requires that the main and power boards are still connected and communicating. How do you guys typically handle that? I'll look around and see if there are any convenient places nearby to tap into those lines otherwise.

Thanks again for the help!

George
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post #8 of 19
10/4/12 at 12:46pm
You're welcome George.

Also agree about having to many cooks in the kitchen.

With understanding the theory of operation and a few multimeter checks on the power board e.g. standby, power on and primary voltage rails), it should not be difficult to isolate the problem to either the main or power board.

Note: Since the relay (RL801) is repeatedly turning on and off, you will not be able to perform the other voltage output checks I mentioned in my initial reply, since it is what turns on the additional primary power supply rails.

However, the relay can easily to overridden (e.g. close its normally open contacts) to either determine if its the mail processor at fault (e.g.not providing the proper level to turn on the rest of the power supply circuits) or an issue on the power board.

One caution while working with the TV is to careful not to put unusual forces on the panel bezel area while handling. The TCON board sends row and column pixel date groups to the driver ICs on the other edge of the panel, and the connections (a.k.a. Tabs) are somewhat fragile (e.g. bad connections will produce vertical and/or horizontal lines).
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post #9 of 19
11/5/12 at 10:18am
Thread Starter 
Pinouts White.jpg 231k .jpg file thiao and all,

I hope somebody's still around on this. I had to put the set aside for a few weeks to take care of some other stuff at home, and am going to try to bring everything back out tonight if I can remember where I was on it.

Before it was put away, I had done the voltage checks you recommended, most of which get sporadic readings which I guess is from the board being powered on/off and failing to come up. The standby line does however stick at 5.34V and appears to be working perfectly for the remote and power button circuitry as mentioned. While the boards were out, I also had taken the opportunity to solder two short jumpers to the switch pins of the relay, so I've got easy access to those if I want to "short it on" as you suggested. Is there any chance that in forcing it to stay on like that, I may run the risk of damaging circuitry which was being protected by that auto shutdown thing it's now doing? I'd obviously rather not break any additional parts.

Thanks also for the tip on how fragile it is. I'll be extra careful. When I first started with it, it already slid off a chair and took a nice bump, but it was more around mid-screen and not enough to physically damage it.

Some minor concerns- The pinouts don't match up 100% between different diagrams I've seen and even what's printed on the PCB silkscreening. I'll attach an image I took of what's on my two boards. Also, as someone suggested, I've tried unsuccessfully to power on with the mainboard disconnected to bring the backlight on and make sure that was working. I don't know if they've changed something in how the circuitry behaves or if that procedure is only relevant for a different model, but in my case, it stays totally dead with AC power connected and the mainboard out of the circuit. I get no ability to turn anything on AND no backlight. Hope that's not a bad sign.

Thanks,

George
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post #10 of 19
11/16/12 at 9:39am
Thread Starter 
bump (still wondering what to do on this one)

thanks
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post #11 of 19
11/24/12 at 5:26pm
Thread Starter 
weekly bump

-Thanks
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post #12 of 19
12/1/12 at 7:14am
Thread Starter 
bump again
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post #13 of 19
12/17/12 at 8:54am
Thread Starter 
two week bump

Anybody?
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post #14 of 19
1/3/13 at 12:17pm
...go to the UNXXC6300, 6400, 6500 thread....the person Squishy Tia may be able to assist you...good luck...I own the 2010 UN55C6400 model~version SQ02 and its a jewel...I hope this helps!
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post #15 of 19
1/22/13 at 9:29am
Thread Starter 
Beerhunt-

Just checking back as I sort of gave up on getting any further replies on it. Set's been leaned up against the wall behind me dead for a month or two.

Thanks for the tip on the thread! I'll go look that up. I think, more than anything, I wanted to get it back up for its ability to run movie files over USB,etc. Very convenient.

Take Care
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post #16 of 19
1/26/13 at 10:17am
@Jidis...good luck ...its a shame to not be able to use that TV
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post #17 of 19
1/28/13 at 7:58am
Thread Starter 
Agree. Also a shame that it probably needs just one of the three boards to get it back up, but I'm not really into buying six hundred bucks worth of them to needlessly replace the good ones. Wish I had a working donor set here to narrow it down.

Take Care
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post #18 of 19
2/11/13 at 6:11pm
any resolution to this? i have un46c8000 that has the same issue. I wasn't positive on how to narrow down to what component is causing the issue so I just bought a new power board online. I haven't received it yet though. I am looking for any reason to return it
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post #19 of 19
2/11/13 at 6:17pm
actually, my power board is completely different than this one. I will still take suggestions if you have any
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