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LCD Flatscreen - Burning smell; flickers then dies.


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3 replies to this topic

#1 HungryEyes

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Posted 17 November 2013 - 07:09 PM

Hey guys,

A week ago, my HP LCD flat monitor had some issues, and I replaced it.

With the intent of salvaging it, I kept it in hopes that I could repair it.

The problems: Upon turning on the computer (thus powering the monitor) the screen lights up and displays like normal for approx. 5 seconds.

After a few seconds, the screen fizzles, the monitor makes an electrical hissing sound, and a faint burning smell manifests. Then, the screen goes dark.

If I turn the monitor off and on again, this repeats itself.

Also, about the screen going dark:
When the screen "goes dark", I mean the backlight. In good lighting, I can still see the faint display in the darkness, there is just no backlight lighting it up.

From the info I gave, does anybody have a clever clue on what the problem may possibly be, or if it's salvageable?


Thank you,

Adam B

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#2 Platypus

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Posted 17 November 2013 - 07:59 PM

Likely candidates would be fractured solder joints on the HV transformer/s that supply the backlight lamps, a bad/arcing connection to a backlight lamp, a failed series HV capacitor on the output to a backlight, or a failed HV transformer or drive transistor/mosfet. A failed transformer would require board replacement, other causes may be able to be repaired by a service center or someone with electronics (hobbyist) capability, ie soldering, component knowledge, understanding electrical safety.


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#3 HungryEyes

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Posted 19 November 2013 - 04:14 PM

Update:

So I have now separated the monitor into two parts (not including the plastic framework).

I now have the LCD panel, and what I believe is the power board, which is still attached to it's metal framework.

I had to disconnect a series of wires to separate the panel from the power board. 

One large connection from the board to the LCD, which was detachable on both ends.
Two small lookalike connections that came from the inside of the LCD panel.


Upon examining one of the small pink and white connections, I noticed that the pink wire was blackened, and had black ash on the metal frame and panel. I believe this is what was causing all of the issues.

I used a flashlight to examine the still-attached power board in the metal frame, and none of the capacitors had a bulging top, although many were tilted a little.

Below are some pictures of the burnt wire coming from the LCD.

Is this fixable? 

Thanks!

 

CAM00338_zps3e6feea5.jpg

 

CAM00336_zpse1f12f0d.jpg


Edited by HungryEyes, 19 November 2013 - 04:14 PM.


#4 Platypus

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Posted 20 November 2013 - 03:57 PM

Yes, looks like there has been a bad contact that has been overheating. Unless another dead monitor can be found to raid, it would be a challenge to find the right connectors to replace those melted. As long as this event hasn't done damage to any electronic components, the most practical repair is probably to eliminate the plug/socket and solder the good section of the wire directly to the solder pads on the board. With the high voltage this line operates at (up to about 1100V to strike the CCFL tube) any charring or carbon deposits need to be cleared away to eliminate arcing. What does the corresponding socket area of the board look like?


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