Monitor Interference

[RedGreenBen]

I bought myself a nice big monitor in the January sales, plugged into my laptop as an extended desktop. However, there are horizontal 'wavy lines' on this second display.

This seems to be caused by interference from the laptop (wireless card is off) as the further I move the monitor from the laptop (at great risk to life and limb) the better it gets. At lead-stretching distances it is a perfect image. Turning the monitor around 180 degrees also does the job, but the back panel is of limited interest. No other electrical items close to the laptop.

Any thoughts/ideas/experience? My distance vision isn't good so having the monitor 8 feet away from my desk isn't an option!

Thanks in advance,

Ben

 

[MrGecko]

have you tried changing the frequency of the 2nd monitor? I have no idea if it will work, but it sounds like you have some superposition / resonance type scenario...

GL

 

[RedGreenBen]

Thanks to both for useful suggestions which I tried but still no joy (I'm *almost* missing having "IT Support"). Tried the monitor on a separate PC in separate location and was fine so now pretty convinced this is interference, also looks a lot like when a mobile rings near monitor.

Going to try some amateur electronics to improve the VGA cable shielding.

Any further suggestions welcome.

Ben

 

[RedGreenBen]

I'll answer my own question for the benefit of anyone now or in the future with the same problem (and to save the many hours research it took me)...

It is EM interference from the laptop power supply, this can be proved by running the machine from battery for a few moments and the problem disappears. This is especially a problem where the power-in and VGA-out are in close physical proximity.

Solution? Buy a properly shielded VGA cable (these are ~£20 so you can see why you will get cheap ones supplied with the monitor). Orientate the two cables to minimise interference by placing them at right-angles.

Ben

 

[RedGreenBen]

Do I get half a bonus point for the fact that my answer contained the words 'power' and 'cable'?

Close, but no cigar

And it took me 11 days to respond, there is just no gratitude on T2W any more