Could large amp be causing screen problem

  aca 19:58 02 Dec 2010

Son has Acer monitor with Xbox/PC going to it via VGA switch box.
The picture both in windows and Xbox has faint wavy distortions visible on dark background. Have tried:

Changing cables and changing switch box
Swapping monitor (same model and in different room the monitor is fine, but replacement monitor starts getting dame problem)
Swapped video card

So it looks like there is something affecting the screen in my sons room. He has 3 amps, 1 large gig bass box. All about 2m away.

Is this a likely cause?

  Nontek 20:12 02 Dec 2010

Could well be the Amps - have you tried with the Amps switched off/disconnected to see if any difference?

  Fruit Bat /\0/\ 20:13 02 Dec 2010


  aca 20:59 02 Dec 2010

Amps switched off but will move them out to see if makes a difference


  woodchip 21:20 02 Dec 2010

What's it like without the switch box?

  aca 21:59 02 Dec 2010


still the same, tried going direct

  mooly 07:45 03 Dec 2010

Is the monitor an older CRT one ?

"Wavy distortions" on a dark background sounds like an analogue signal being affected by stray 50/60hz (depending on country) pickup or ground loops caused by the way it's all connected and earthed.
Can be very hard to pin down sometimes. You need to connect things one by one, PC and monitor, then start adding.

Is it worth altering and checking the frame refresh rate on the monitor...

  aca 08:09 03 Dec 2010


Srry should have said the monitors are LCD.

Will try reconnecting all again, and also removing the amps from room.


  grey george 11:34 03 Dec 2010

If you have a long extension lead you could try powering the monitors from another room. It may be there is something causing noise on the sockets only in this room.

  Bris 16:38 03 Dec 2010

This may sound like a daft solution but I have known it to work in the past. Find a carboard box larger than the screen and cut the front out of it then line the top, sides & back with kitchin foil and place the box around the monitor making sure that no foil comes into contact with any live cables or parts. The effect of this is to screen the monitor from any stray interference. You obviously wont want to keep the box in place but can move it around until you identify the device causing the problem. If you still get the interference then it could be the coming via the feed cable.

  aca 22:21 04 Jan 2011

tried most of things and still no good, so any further thoughts appreciated

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