LCD screen cloud marks

[almoodie]

I have a working Samsung 215tw monitor which has "cloud marks" on the display. If I display a white page on scree the marks appear like water marks on paper which has been wet. The cloud marks are in the middle of the screen and annoying.
I have another Samsung 215tw which does not work. The panel itself or the board that drives the panel (fused to the panel) does not work, shuts down the inverter.
I have this non working monitor panel apart, with 3/8" thick heavy diffuser, and 4 or 5 clear or clouded thin plastic sheets, etc.

My question: If I use the 3/8" thick heavy diffuser, and 4 or 5 clear or clouded thin plastic sheets from the non-working monitor in the working monitor will it cure the "cloud marks".
I'm not sure the screen from the non-working monitor is "cloud mark" free but looking at the condition of the whole monitor there a very good chance that it is.

Is this a worthwhile venture.

[seanc]

Re: LCD screen cloud marks

I would just swap the LCD panel from the dead monitor to the cloudy monitor and see what happens.

[almoodie]

Re: LCD screen cloud marks

I would just swap the LCD panel from the dead monitor to the cloudy monitor and see what happens.

Tried that, the LCD panel from the dead monitor still no backlight even when all other components are known to be working.

[freelander]

Re: LCD screen cloud marks

Be very careful when you are taking these apart since I killed one of my first repair attempts by separating the tape carrier by accident. To answer your question, yes you can swap components but remember that these are put together in a clean room environment. Any dust, oily fingerprints, etc will show up when you are done. Can you post a picture of what it looks like?

[almoodie]

Re: LCD screen cloud marks

Be very careful when you are taking these apart since I killed one of my first repair attempts by separating the tape carrier by accident. To answer your question, yes you can swap components but remember that these are put together in a clean room environment. Any dust, oily fingerprints, etc will show up when you are done. Can you post a picture of what it looks like?

Freelander, you are correct, exactly as you said, one of the solder joints at the end of one of the CCFL tubes had failed, presumably leading to arcing. Images are attached.

For those who have never seen the guts of a panel here goes:

Image 1: Essentially a metal tray with a sheet of white glossy plastic in the bottom. The angled pieces (wires attached) lying to the side each carry 3 CCFL tubes. These angled pieces slot in top and bottom in the tray creating a wall of light

Image 2: One of the two angle pieces which carry the CCFLs

Image 3: A 3/8 inch slab of clear plastic which sits in the main panel tray. On top of this sit 3 layers of plastic sheet (not shown). I guess they are polarizers, diffusers, or the like.

Image 4: The failed CCFL return wiring

Image 5: A bank of 3 CCFL tubes with wiring

Image: 6 Closeup of CCFL ends with charring. White end piece is rubber and broken up somewhat with the charring.

All the pieces are quite robust but I had to get my 17 year old daughter with her small hands to disassemble to CCFLs from the angle pieces. Have to go get some wire fine enough to rewire the CCFLs tomorrow, together with a can of compressed air and a microfiber cloth, the poor man's answer to a clean room.

This is all very interesting but probably an uneconomic exercise. Plus the big question is whether I can put this thing back together in an acceptable state of cleanliness such that I get a usable monitor.

[freelander]

Re: LCD screen cloud marks

I was thinking a picture of the cloud effect on your assembled monitor.

By the way, I had one monitor that had a smashed panel but good bulbs. When you take this apart, you can easily move the panel between your good and bad units leaving the glass and bulbs in place. Removing the glass and bulbs is a delicate task that can introduce dust and debris so limit how long you leave this exposed. I used the exact same routine of compressed N2 in a can and microfiber to clean glass that had residue on it.

You will immediately see any dust particles, hair, etc if it is still on the glass when you re-assemble but the good news is that it is easier to identify the location to clean!!

[Krankshaft]

Re: LCD screen cloud marks

These cloud marks sound like someone may have disassembled the panel before you.

If you use any type of cloth you will introduce these marks not only that it will create static electricity that when discharged can fry the LCD driver board.

If you must remove dust use compressed air only.

I've made a impromptu DIY clean room with box fans and HEPA filters in the past. A clean room is nothing more than a room devoid of dust with filtered air.