Sharp LC-26SB14U White Screen

[CleanSC]

Fellas!

I have here in front of me a friend's Sharp LC-26SB14U that does nothing but power up to a white screen.

I cracked it open and the PSU doesn't have any obvious bloaters.

Changing the input does nothing, channel does nothing. Raising the volume does raise the no signal noise a little bit.

I am guessing the PSU is not powering the logic board, or the logic board is just dead. There seems to be power reaching everywhere else on the tv.

Anyone have any suggestions or typical fixes for this?

I attached some pics so you get an idea of what's going on inside.

Just wondering if anyone has had any experiences with these tv's. It died 3 days after the warranty period expired.

[retiredcaps]

Re: Sharp LC-26SB14U White Screen

I have here in front of me a friend's Sharp LC-26SB14U that does nothing but power up to a white screen.

I am guessing the PSU is not powering the logic board, or the logic board is just dead.

Post a picture of the logic board. I'm pretty sure it is hidden underneath that aluminum shield. Try to get in as close as possible with the highest resolution.

[70JUDGE]

Re: Sharp LC-26SB14U White Screen

Have you tried to reseat the cable that goes to the screen?Does your screen turn black afterwards,or have sound?I saw the exact model on Ebay that powers on to a white screen,then turns black.I hope this helps.Thank You very much!
Tyler

[Wizard]

Re: Sharp LC-26SB14U White Screen

T-CON or mainboard. Unplugged LVDS cable always is black LCD even backlight is lit.

White LCD is all pixels are on letting light through, and that requires power and command from mainboard. Or defective mainboard or bad T-CON.

Cheers, Wizard

[Agent24]

Re: Sharp LC-26SB14U White Screen

While troubleshooting an AOC 17" I found that disconnecting power to the logic board and powering up would result in a white screen.

The overall fault was just bad capacitors in the PSU.

[CleanSC]

Re: Sharp LC-26SB14U White Screen

Below are the requested pics. I hope they are good enough.

Judge, yes, I have tried to reseat all the cables, and still the same result. No black screen, always white. No sound, except for the faint hiss of the amplifier being on, but with no signal input.

Let me know what you all think.

Thanks, fellas!

[Agent24]

Re: Sharp LC-26SB14U White Screen

You said that you suspected no power to the logic board, did you check this?

[CleanSC]

Re: Sharp LC-26SB14U White Screen

You said that you suspected no power to the logic board, did you check this?

No, because I have no idea how.

The connectors to the logic board have 23 pins each and I have no idea which one does what. They are not labeled on either board and I don't have any electrical diagrams.

Is there a way to find this information?

Thanks, Agent!

[CleanSC]

Re: Sharp LC-26SB14U White Screen

Here's some shots of the PSU. I'd love to know what the pinouts are of connector CP401 so I could check if the logic board is getting proper power.

Any clues on this?

I can take any close ups of any particular areas on request.

Thanks, fellas!

[CleanSC]

Re: Sharp LC-26SB14U White Screen

SCORE I found the service manual online. This will obviously help tremendously.

If anyone can help lead me in the proper diagnostic direction using these schematics, I'd be very appreciative.

I have checked the power outputs of CP401 on the bench and most seem to be in order. The rest, I'm not sure if the PSU needs to be connected to the other boards and the TV turned on to get the proper voltages. I haven't done this yet.

I have uploaded the service manual to my own server for your convenience.

Thanks in advance!

Right click, Save As... (Doesn't read right in browsers)

[mbates14]

Re: Sharp LC-26SB14U White Screen

rip it all apart and check the SMD fuse on the T-CON panel driver board. I once had an older olevia do the "white screen of death" and replacing this fuse fixed it. Maggies were known for a mosfet failing on the mainboard causing white screen of death, because no power would reach the panels t-con

But i had an AUOptronics panel in an HP monitor have the same white screen of death, same blown fuse, but it re-blew, and i found the DC-DC converter that was built into the panel driver/t-con was shorted.

my 2 cents

[CleanSC]

Re: Sharp LC-26SB14U White Screen

Good idea... Would you happen to know which component this would be from my pics? Or generally what area this should be in?

And checking is simply seeing if there is continuity thru it like any other fuse, correct?

[Agent24]

Re: Sharp LC-26SB14U White Screen

Good idea... Would you happen to know which component this would be from my pics? Or generally what area this should be in?

And checking is simply seeing if there is continuity thru it like any other fuse, correct?

I personally have no idea where any fuses may be but if there are any fuses they should be in the schematic in the service manual you downloaded.

From there, you should be able to find them on the PCB.

Yes, you would want to check for continuity. Good fuse should read almost 0 ohm, blown fuse will be infinite.

[retiredcaps]

Re: Sharp LC-26SB14U White Screen

And checking is simply seeing if there is continuity thru it like any other fuse, correct?

Just a caveat with using the continutiy (beep) feature on multimeters. This varies greatly between different multimeters. On mine, continuity is 25 ohms +/- 10 ohms. When measuring a picofuse it beeped good, but in reality at 19 ohms it was a bad fuse.

On some really cheap multimeters, I read their manuals and continuity is anything less than 1.5k ohms.

So I suggest just using 200 ohms if you have a manual multimeter and looking for 0.3 ohms.

[CleanSC]

Re: Sharp LC-26SB14U White Screen

I have confirmed (I think, hah) the logic board is getting all the voltages it should need to work. The 30v and 5v lines are all reading their respective values.

As far as I can tell, the logic board has no fuses on it. I'm pretty sure I have confirmed this using the diagrams.

So, in my very inexperienced opinion, the logic board is fried.

Being that this may very well be the case, where do you all usually source these boards? Just googling the part numbers?

Thanks, fellas!

[Dgtech]

Re: Sharp LC-26SB14U White Screen

For some, there are sites that sell boards like that and yes google will find you those sites. For me, I use ebay to try and keep the price low however..... there are lots of people that sell faulty stuff on there too. Knock on wood, I have only gotten about two defective things out of about 90 things bought on ebay. Sometimes people sell good cards out of units that have had physically damaged screens. These should have no problems.

Good luck with your search.

[Dgtech]

Re: Sharp LC-26SB14U White Screen

I just seen one on ebay for $69.00. This was taken out of a 24 inch unit. That has the same board number. I dont know if there is any difference in firmware/eprom (if any) programming for the different sizes. I'd need some of the more skilled techs to confirm that.

[mbates14]

Re: Sharp LC-26SB14U White Screen

the board I am referring to is the board that your LVDS cable is going up to on the LCD panel itself. This board usually causes the white screen of death. in most cases. not all...

You cant see the board, because its up under the metal frame that seperates all your boards from the panel. Youll see a square "buldge" thats at the top center of your metal frame plate. thats the board you need to get to.

[CleanSC]

Re: Sharp LC-26SB14U White Screen

the board I am referring to is the board that your LVDS cable is going up to on the LCD panel itself. This board usually causes the white screen of death. in most cases. not all...

You cant see the board, because its up under the metal frame that seperates all your boards from the panel. Youll see a square "buldge" thats at the top center of your metal frame plate. thats the board you need to get to.

Okay I have located this board... It runs along the top of the panel and is about one inch wide by 21 inches long. I scoured the whole board and only found one component, FP1, which looks like it could be a fuse. It's an SMD white square with a K on it. Not sure if that's it, but it measured .1 ohms so it's not broken. Couldn't find anything else on that board that looked anywhere remotely fuse-like.

Thanks for the direction!

Any other ideas before I trash this thing? Now accepting offers!

[retiredcaps]

Re: Sharp LC-26SB14U White Screen

It's an SMD white square with a K on it. Not sure if that's it, but it measured .1 ohms so it's not broken.

K = 1.5A according to

http://forums.xbox-scene.com/index.php?showtopic=658938