View Full Version : twin monitors show strangeness

05-25-2001, 12:24 PM
So get this. I just set up my new monitors last night, two 17" NEC AccuSync 75Fs. They seem to be pretty decent monitors. My left monitor is running on an ATI VR Rage Pro (with Apple-only connector) and my right one is on an XClaim VR 128. I plugged both monitors in, using an old adaptor I had for the Apple port, booted up and they both came up right away. No problems whatsoever.

I went to the Monitors control panel to set their settings. I had them both set for 1024x768 at 85Hz. I thought about going with 1152x864@75Hz, but decided to wait until later.

After I went on the web for awhile, I noticed that my left monitor had a very faint very blurry dark band, not very big, that I would not have noticed if it hadn't been travelling down my screen, then starting over again at the top. Then I realized my left monitor had one too, but it was going up the screen and starting over at the bottom. Again, not very noticeable if it hadn't been for the fact that they were moving, at a moderate pace.

I tried degaussing several times, which it appeared the tubes badly needed, but it didn't change a thing. Then I went back into the control panel and set the left monitor for 1152x864, while the right monitor remained as is.

Suddenly it appeared that the bands were gone from both screens. As soon as I set the right monitor to match the left, though, the bands came back, this time a little darker and moving faster. So I set the left monitor back to its original 1024x768 setting. The bands were gone again.

I don't really want to have my monitors set at mismatching resolutions, and besides, when they didn't match I noticed that whichever monitor had the slower refresh rate had some faint flickering or pulsing going on the side of the screen next to the other monitor. So that's not really good either.

Yes, these monitors are set right next to each other. They are at a slight angle to each other with the corners of their cabinets touching. Is it possible that they are interfering with each other? Could I solve it by mounting some kind of metal plate or sheet between them to shield the interference?

05-25-2001, 12:42 PM
Yep, that's monitor interference. The things put out some pretty powerful fields. They are more likely to interfere with each other when they are set to the same frequency. You need to spread them further apart. On my desk, I keep the subwoofer of my speakers between the two monitors. Shielding might help but the fields extend out in a sort of sphere/cylinder thing, so you might need to shield a surprisingly large area between the two monitors.

My housemate's first monitor is about 18" from one of mine and whenever one of us turns our monitors on, the other's monitor does a little jig. The degauss is that powerful.

05-25-2001, 10:49 PM
Just for the record, 1/4" mild steel (A36) will shield the magnetic fields dispersed from monitors or speakers. I had the same problems and I remedied them by tweaking the refresh rates and positioning a piece of steel plate.

05-25-2001, 11:59 PM
I have used cookie sheets in the past just fine.

practice looking dumb before your wife asks if you've seen them!


05-26-2001, 11:54 AM
Mag- not married yet. That happens in September. Thanks for the tip, but I know better than to show my face in the kitchen, let alone make non-kitchen use of kitchen implements. I'll go buy some.

I did try using the removed side-panel from my PTPro this morning, slid between the two of them, and I did notice an improvement. I thought I could still make out the lines if I looked for them, but I had to REALLY look for them, and even then half the time I thought it was my imagination.

This will be a fun project, I was going to build a foam-core hood for the twin monitors anyway, spray-painted black, so that will be a good way to mount the cookie sheets at the same time.

05-26-2001, 06:05 PM
September....that's a good time. You miss the rush in July. I think I was married in late June.

yeah,that's it. Late June.

get firecrackers. Have the kids blow off LOTs of firecrackers, and send 'em up HIGH. (Call the sheriff first and invite him to the party so he knows what's going on and can run interference in case the city cops come rumbling in).


05-26-2001, 06:07 PM
Since it sounds like you have very mild interference, you might even be able to get away with using foil.

I have the inside of my desktop TV's case shielded with simple aluminum foil, and this eliminated the problem between the TV and adjacent monitor.

Of course I don't need to tell you that if you choose to line the inside, you need to be careful of both heats and electrical concerns...

05-28-2001, 06:29 PM
Dude, this is the_anarch's answer to the PressView.

Screw those guys anyway! Fight the power!!!

[insert monitor hoody graphic here...]

05-29-2001, 10:49 PM
Fire chaff every 6 seconds!