Interferences on NEC 2690WUXi

H

_HU_

Weaksauce
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Oct 21, 2008
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OK guys, I posted this before but, due to problems with the web database, my post was lost.

My problem is I see (faint) horizontal lines running from bottom to top under certain conditions: mainly with grey and blue backgrounds and only in the left corner of the screen (in the right corner I've noticed nothing).

Somebody told me the issue could be generated by the quality power. The quality power is good (as far I know). My monitor is using the shipped cables (power and data cables). I've tested the monitor with DVI-I, DVI-D and DSub connections (with shipped cables) and the result is the same, but with DSub connection perhaps these lines are less visible. This annoying effect is more noticeable when brightness is near to 0%.

I have to say too that the monitor was repaired at the Technical Service in France, therefore the unit should be OK and the problem could be my graphics card, my electrical installation or whatever, who knows. What do you think?

Thanks very much for your help.
 
The "quality power" phrase refers to how "clean" the power is coming out of your electrical outlet. The amperage and voltage coming out from an electrical outlet can fluctuate which can cause some issues with electrical equipment if that fluctation is too much. I know this is an issue with some high-end audio equipment (audiophile level stuff) which are sensitive to this type of issue and can cause sound coming out of the speakers to fluctuate.

Try connecting your PC and monitor to another outlet in a different room, preferably a one that is connected to a different circuit breaker.
 
When you say "horizontal lines running from bottom to top" you mean the lines run from side to side, and form a pattern vertically right? This is a known issue with all monitors using that panel, and apparently some units show the defect worse than others. My DS-263N shows the lines on the entire panel, but they are only visible on greyish colors at a distance of 8 inches or less.

It seems to be an effect of the gaps between the pixels, which is why raising the brightness makes them harder to see.
 
When you say "horizontal lines running from bottom to top" you mean the lines run from side to side, and form a pattern vertically right?
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Yes.
This is a known issue with all monitors using that panel, and apparently some units show the defect worse than others. My DS-263N shows the lines on the entire panel, but they are only visible on greyish colors at a distance of 8 inches or less.
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Yes, I'm agree with you but only it's visible on blue and grey backgrounds and not always.
It seems to be an effect of the gaps between the pixels, which is why raising the brightness makes them harder to see.
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Aha, thanks for the tip but, why this effect is NOT noticeable on the right side of the monitor? (only on the left side).

@JaguarSKX:
Ok, thanks for your fast reply. But I must say this issue is not affecting my other monitor, a NEC 20WGX2 plugged to the same source power. Is it possible this issue only affects *certain* models?

I don't understand why a TOP CLASS monitor as this has this annoying effect. I payed for it more than 1000€... :(
 
Well, a friend of mine told me that the problem is generated by the power supply of the monitor, therefore, this would explain why lines are only visible in the left side and not in the entire screen. The monitor has a power switch in the rear left side, the same place where the power supply is located (probably). The theoretical explanation for this is the power supply is generating a frequency multiple of the refresh rate, generating signal harmonics ("interferences"). I've PARTIALLY solved this issue changing the refresh rate to 63Hz instead of 60Hz standard. Now lines are subtle, but the problem is not solved.

I need your help in configuring my graphics card (NVIDIA 6600GT) optimally to get rid of these lines. Thanks again.
 
_HU_ said:
I don't understand why a TOP CLASS monitor as this has this annoying effect. I payed for it more than 1000€... :(
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Everything can have defects, even brand new top class gear, unfortunately.

If this is new or under warranty, send it away... I don't think you state if it's always done this or if it developed after a long period of working properly.
 
_HU_ said:
Well, a friend of mine told me that the problem is generated by the power supply of the monitor, therefore, this would explain why lines are only visible in the left side and not in the entire screen. The monitor has a power switch in the rear left side, the same place where the power supply is located (probably). The theoretical explanation for this is the power supply is generating a frequency multiple of the refresh rate, generating signal harmonics ("interferences"). I've PARTIALLY solved this issue changing the refresh rate to 63Hz instead of 60Hz standard. Now lines are subtle, but the problem is not solved.

I need your help in configuring my graphics card (NVIDIA 6600GT) optimally to get rid of these lines. Thanks again.
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Ohh, by 'running' you meant the lines move. If they go away at high brightness it's more likely the backlight modulation itself producing the waves, not an outside source of interference.. That would be a defect in the display. If they're still visible at high brightness, just less so, that's two defects. You should try to get the monitor replaced under the warranty.

If that's impossible, panel blocking can reduce brightness without pushing the backlight out of its comfort zone. This will also reduce the contrast ratio, and therefore overall image quality, so it's not a great solution. To do this with your video card, lower brightness in the nVidia Control Panel.
 
Thanks for your replies.

The monitor was repaired at the Technical Service in France, as I said in a previous post. The entire panel (LM260WU1) was replaced due to green tints in a corner (not produced by the A-TW polarizer, these tints were visible in front of the screen). Therefore, the unit has been revised in the service center.

What do you think about the signal harmonics commented above?

Thanks again
 
_HU_ said:
Please, give me some inputs... Thanks
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I believe that we have. It sounds like it's under warranty, and the problem started after it was repaired for something the first time. Get it fixed again. Keep going back until it works properly. Escalate directly to NEC if the repair center keeps screwing it up.
 
Well, it seems the problem is intermittent. I have made some tests more at the morning and I cannot distinguish any waves at all under the gray background even in a dark room. Therefore, I have mailed again to the technical support and they told me is a "electric interference problem. Verify all machines plugged in your house and in your neighbours houses ".

I really think it's not a problem of the monitor itself, but any electrical appliance perhaps (?)

What do you think about this last comment? Thanks
 
I wouldn't want to personally say "impossible". CRT technology is vulnerable to electric and magnetic fields and can cause analog rippling effects like this. This simply isn't a factor for LCDs with all-digital inputs. I wouldn't believe it for a second.

Couldn't rippling in the CCFL itself (like a marginal or burnt out fluorescent bulb) cause exactly this issue? Not having ripped apart a pro-grade LCD myself, I don't know a lot about the CCFL system.
 
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