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Anthony_Infotech
Anthony_Infotech, Technician
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i have a Sharp Aquos lc-42d62u that has audio, but no pict

Customer Question

i have a Sharp Aquos lc-42d62u that has audio, but no picture.
Submitted: 4 years ago.
Category: TV
Expert:  Anthony_Infotech replied 4 years ago.

Hello

Thanks for using this service

Welcome to JustAnswer

 

Is the screen completely black?can you bring a menu up at all?

 

Can you see if the screen is lit at all even if its feint you may notice more in a darkened room?

 

Anthony

Customer: replied 4 years ago.
It will come on for a second, but then goes black. I don't have input to it right now so it's sowing just "analog" in the upper right hand corner with just static on the rest of the screen. I don't have the remote, kids broke it awhile ago. Can I access the menu via a different pathway?
Expert:  Anthony_Infotech replied 4 years ago.

Hello

 

What I'm trying to establish is what fault you have

I only asked you to bring the menu up as a check it plays no further part

Are you saying this is an intermittent thing ie goes black?

 

You say now you have something on the screen?

 

What I need to know is exactly what is wrong with the set so if you just start from the begining when it started and if it comes and goes as i'm now confused!

 

Regards

Anthony

Customer: replied 4 years ago.

When I turn the set on it shows some static on the screen with "analog" in a blue box in the upper right hand corner. This happens only for a second then goes black. If I hook up a DVD player to it, the screen stays black, but for a second "Component" comes up in the blue box in the upper right hand corner. However, if I play the DVD, I get audio with no issue. Other than the second the screen comes on, it is staying black. This does not happen intermitently (sp?). When I have the back panel off and I look at the card that has the 2 HDMI, Optical input and Cable port I can see two very small red LED lights. They appear to be lights that are built right on the board, and one is on constant and the other is blinking. This, I have no idea, means anything but want to offer it up as more info. As of right now the set is sitting on my kitchen table with the back panel off and nothing hooked up, hence the static showing and "analog" coming up, but again this is only for a second.

We had a wind storm that came through over the weekend and power was lost for a split second, so I'm not sure if a surge occured. I'm hoping this helps and please let me know what other information I can offer.

Thanks!

Expert:  Anthony_Infotech replied 4 years ago.

Hello

 

OK its not the backlight out then which is what I initially thought

If the graphic is appearing on the screen it would appear as though you have an issue with the mainboard or LCD control board

I'm afraid with this technology its a board changing exercise, mainboard most suspect, this will be were you are seeing the blinking leds, I will consult the service manual and ask Sharp Technical if their is any bulletins so get back to you later

 

Anthony

Customer: replied 4 years ago.

Sounds Great! Swaping the board doesn't appear to be an issue. From looking at it, it looks as though you shouldbe able to unfasten and unplug, then swap. I look forward to getting more information from you.

Thanks again!

Expert:  Anthony_Infotech replied 4 years ago.

Hello

 

I'm just waiting on some info be back real soon

 

Anthony

Customer: replied 4 years ago.

Sorry, have been in meetings all day. Let me know when get more information or if you need anything else frommy end.

Thanks!

Expert:  Anthony_Infotech replied 4 years ago.

Hello again

 

Their are 2 different mainboards for this set

The cheapest I could find is from this pulling site, they are pulled from used sets

 

http://www.shopjimmy.com/sharp-duntkd934fm11-main-unit.htm

 

http://www.shopjimmy.com/sharp-duntkd934fm03-main-unit-for-lc-42d62u.htm

 

http://www.shopjimmy.com/sharp-cpwbx3520tpzd-lcd-controller.htm

 

You would have to check on your board the ref numbers as indicated for the mainboard

 

Good Luck with it

 

I would go for the mainboard first make sure you get the right one!

 

Regards

Anthony

Customer: replied 4 years ago.
Do you know where on the board I would find out the exact version of the board? Thanks for the links! The two there appear to be very close to the board that is in it, but mine is a different version and has a black mark on the "B" on the top where those have either an "H" or "C".
Expert:  Anthony_Infotech replied 4 years ago.

Hello Karl

 

I'm only aware of 2 different versions of this board in the link their is a reference to a label on the board that should tie up with the label on your board?

 

I have technical access to sharp with my employers and their is only 2 versions

 

Sorry but the info at the site simply doesnt give a clue neither do the bulletins

 

Anthony

Customer: replied 4 years ago.
As I look on the board it has a white label with "WE0368M M" printed on it. The two other boards that you sent the links have different info printed on the label in the same location as well as an additional wired connector that mine does not have. Do you think they are just updated versions?
Customer: replied 4 years ago.
I think i have figured it out. On one of the links you sent it references the board model KD 934 and also WE 03xx. Mine is KD 934 and WE 0368, so I am thinking that should be the one. Correct?
Expert:  Anthony_Infotech replied 4 years ago.

Hello again

 

To be honest I don't know

The two boards have different codings according to shopjimmy

 

Try www.partstore.com and www.encompassparts.com and input them part numbers it may direct you better

 

Anthony

Customer: replied 4 years ago.

After fooling around more this and reading more. If I hold a flashlight to the screen I can see the video. I'm not sure if this is a backlight issue? When the tv turns on, the video comes on for a second as if normal, but then goes dark. It is at that point that you can hold the flashlight close and see the video is indeed on, just dark. I can see on the back of the unit that there are two boards(while looking at the back with cover off), one on the left that has 10 connectors going to the LCD screen and one on the right with the same connectors, but the board is slightly different. Both are the same size, but the one on the left is marked "Master" and has more stuff on it, while the one on the right is marked "Slave" and doesn't appear to have as much too it other than the same amount of connectors going to the LCD screen. Would both boards be bad?

How do you know if it is a bad bulb or inverter? I can see the bulb lighting up for a couple of seconds both on the display and from the back of the set.

Thanks again for your help.

Expert:  Anthony_Infotech replied 4 years ago.

Hello

 

You did say that a graphic came on analog/component

Are you now saying the picture comes on for a second then goes off?

 

If so and is a common issue with the backlight going out

Usually its poor earthing on the inverter just tighten all the screws up attaching the inverter to the chassis as the inverter is earthed at them points, if it comes on this will be the issue

 

Anthony

Customer: replied 4 years ago.

I have taken the screws out of both of the master and slave boards, retightened both. I didn't see any oxidation at any contact points. With a DVD playing through one of the inputs, the picture will come on for a second. Without any feed it comes on with just static, again for just a second. It was upon reading about the flashlight trick that we noticed the picture was actually still there. Do you suggest using an eraser or sanding the contact points lightly, or do you have another opinion. Do you think that one of the inverter boards or backlight is bad?

Thanks!

Expert:  Anthony_Infotech replied 4 years ago.

Hello again

 

I see what you mean now

 

Yes the flashlight will light the pixels so proving that indeed the backlight is going out

You can try and clean them earthing points, most likely is either of the inverters being faulty or the backlight itself is faulty

Their is an insitu tool to check the backlight some companies have them

Other than cold dry joints on the inverters just about anything on their can shut off the backlight

The inverter supply from the powerpack usually 20 to 40 volts should also be checked to make sure this isnt disappearing but this is unlikely, the mainboard also has control on the inverter function and isnt ruled out either so in order of most suspicion, the inverter(s), the backlight (hopefully not),the powerpack supply,the mainboard control

 

Sorry its getting complicated

 

Anthony



Edited by Anthony Pr on 12/6/2009 at 12:15 PM EST

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