View Full Version : Anyone know of a good product to eliminate EMI/RFI?

06-04-05, 08:12 AM
Basically, I took a new CRT I got at a local computer shop back to my apartment, hooked it up, and discovered that the black levels were awful and the screen shook violently at any refresh rate between 70hz to 85hz, but not at 60hz and not at >85hz (the monitor can do 100hz at 1280x960). I took it over to a friend's house and hooked it up to find that it was the most outstanding image I've ever seen on a computer monitor - the color was absolutely perfect, the image was rock solid. We brought his computer over to my apartment to test if it was my hardware causing the problem, but it wasn't - the monitor shook badly even hooked up to his computer, and the color was awful again.

Basically, there is a large amount of EMI or RFI (or both) on the line, which makes sense. I've never noticed it before because I've been using an LCD ever since I moved in here. Anyway, I picked up a surge protector ($25) at Best Buy yesterday and it really didn't help at all. So now I'm looking for a product (preferrably by APC) that will condition the line and eliminate the interference. Any of you guys know of a good one?

06-04-05, 08:40 AM
LOL, that's one of the reasons I got rid of my CRT - it was doing that pretty badly in the last place I lived @.

I use an APC Back UPS Pro. APC is pretty much the industry standard.

If you get a line conditioner on there and it still exhibits this behavior then I'd start pulling the plug on your appliances and other devices until you narrow down just WTF is causing this.

06-04-05, 09:44 AM
OK, just got back from Best Buy with a new APC Back-UPS XS series (BX800). It didn't do a damn thing.

06-04-05, 09:45 AM
Start turning things off in the house. It's the only way to find out what device is causing all that noise.

06-04-05, 10:42 AM
I turned off everything, unplugged everything, it didn't do a damn bit of good. :p

Oh well, I give up. I still have this nice LCD and I needed a good UPS anyway so I'll keep it. There is actually a rather large transformer grid right across the street so there's probably just some big magnetic field that's doing it (though my TV is fine). I'm just going to take the monitor back.

06-04-05, 11:20 AM
Back to the LCD eh? Ah well. Perhaps it's fate. :)

The next thing I was going to suggest was power line interference. Bummer that's probably the case then. FWIW I have a buddy of mine with the same problem. Can't use CRT monitors without interference and it just about has to be power lines because he's done the same testing you have. What else could it be eh??

06-04-05, 11:21 AM
Ah who knows. Well, I learned that CRTs are not an option, and got a nice new UPS backup system, so I'm no worse for wear. Thanks for your input.

06-04-05, 12:22 PM
It sounds more like you have a defective monitor

06-04-05, 12:57 PM
It sounds more like you have a defective monitor

If it works fine elsewhere it's definitely the power in his house.

I've experienced the same thing with literally DOZENS of crt monitors in my house. Any crt monitor will shake and vibrate unless it's on 60hz in this house. Take those monitors to another building and they are perfect on any refresh rate.

06-05-05, 03:06 PM
For one thing EMI and RFI travel in the air, not in you power lines.

Problem point's to bad soldering joint in monitor. When you took it to your friends house, It probably made a better connection.
Try wacking it. (not too hard lol) This whay you can tell if it's a bad joint. If the screen flickers when you do. You can either take it to a repair shop or buy a new one.

also weird unsuported resoulutions can do that too. Anything other than 800x600, 1024X768 or 1200x1024.
1024X 768 is standard res for desktop. It should handle this at 85hz.

to trouble shoot, enter safe mode or vga mode. Hold f8 during reboot.

If no flickering then no bad soldring joint (alternative to wacking). Then set it to 1024x768 at 85 see how that works.

Ensure you got the latest video driver installed as well.

06-05-05, 10:40 PM
Some more info...

We had a LAN party here this weekend. Everyone's CRTs did the exact same thing mine did, so I can rule out any problems with this monitor in particular. In addition, some of my friends that live in the same apartment complex have this same problem with their computer screens, and just got used to it. It seems there is a strong EM field around us, so back to LCD I go. :)

06-06-05, 12:57 PM
Are you sure your outlets are properly grounded?

06-06-05, 02:01 PM
For one thing EMI and RFI travel in the air, not in you power lines.

While that may be true, in my last apartment I had the same problem and I was able to significantly reduce it by moving the computer as far away from backside of the apartment as I could get. There were power lines, telephone lines and the A/C units that ran along the backside of the apartment complex. It was definitely some sort of interference causing it and not the monitor. The monitor was and is fine everywhere else I've been.

06-06-05, 03:49 PM
Unfortunately the power & telephone lines are very very close to my apartment so I can't move the monitor far enough away from them to get it to work properly.

Yes, my outlets are grounded properly.