vertical LCD screen lines

[mpolo]

Curious if anyone here knows what is going on...

My work had a busted LCD monitor here (Syncmaster 206BW). I replaced the capacitors on the power supply, and brought it back to life... well sort of.

The monitor has vertical lines across the whole screen, with varying intensity.

Here is a link to how it looks.

Updated image link

The caps I used were the correct ratings... So did I do something wrong, is it something else?

Thanks in advance.

 

[SecurityTheatre]

If you look closely, can you tell if it is a single row of pixels that is not lighting? Is there any pattern (like are they uniformly distributed, or random)?

 

[mpolo]

If you look closely, can you tell if it is a single row of pixels that is not lighting? Is there any pattern (like are they uniformly distributed, or random)?

Not sure what you mean by single row of pixels, as it affects the whole screen from top to bottom.

There is a sort of pattern, the lines seem to be grouped in an alternating inch wide darker band of vertical lines that start off about 1.5 inches in width, grow to about 2.5 inches in width at the center, then back to 1.5 inches and the right side.

The pattern feels a bit logarithmic to be honest.....

 

[Chrishuff1]

Tried another cable?

 

[Matt1970]

I can't get your image to load.

 

[mpolo]

Strange, maybe I posted a link that only I could access. OP has been updated.

Thanks!

 

[PottedMeat]

have you tried different video cards, also have you tried both interfaces - VGA and DVI?

 

[C1]

Looks like noise. It is possible that there is more wrong with the power supply section (than you supposedly repaired) and that what you are seeing on the LCD screen is electrical noise superimposed on the supply lines.

Normally one would check the power noise using a scope. The number of lines on the LCD tell you something about the frequency of the noise. (Been long time since my TV repair days.)

Ensure that the replaced capacitors are of the same type (eg, metal shielded with same kind versus ceramic). Ensure all PS shielding involved with the repair(s) is in place. If possible, temporarily substitute PS line from a known good source such as from an external power supply.

 

[Matt1970]

I am thinking the screen it'self is a little out of whack. Can you push on one of the areas with the lines and see if it goes away?

 

[bryanl]

I agree with C1 since problems in the LCD panel itself tend to be sharp and focused, like dead or bright pixels or vertical or horizontal lines. If the patterns change with the video source or resolution, it's not the panel.

If the replacement capacitors have much lower impedances (or ESR values) than the originals, they can make switching power supplies put out more noise.

 

[mpolo]

Looks like noise. It is possible that there is more wrong with the power supply section (than you supposedly repaired) and that what you are seeing on the LCD screen is electrical noise superimposed on the supply lines.

I agree with C1 since problems in the LCD panel itself tend to be sharp and focused, like dead or bright pixels or vertical or horizontal lines. If the patterns change with the video source or resolution, it's not the panel.

If the replacement capacitors have much lower impedances (or ESR values) than the originals, they can make switching power supplies put out more noise.

Excellent advice guys. I picked up the caps from a local electronic supply store and I have a feeling they were general purpose, rather than the lower impedance types. I guess that means I need to break out the soldering iron again! Not sure when this will happen, but when I do I will update this post with the results.

Many thanks for the expert knowledge!