Bleg for Help with Wavy Monitor:

My home computer setup has a Samsung SyncMaster 213T LCD monitor. For no reason that I can discern, a couple of days ago I started to get pretty major "wavy" interference on the monitor. I unplugged it and hooked it up to my wife's computer, on a desk a few feet away, and it worked fine, which I suppose must mean that the monitor is okay, but something nearby is causing the problem. I moved it back to my desk, and promptly got the waves again. I haven't moved any electronics around lately that I can remember. Any ideas? Thanks.

Romach (mail) (www):
Try testing another monitor on your computer (preferbly with the same and with different cables) to figure out if its your video card or something in the area.

Out of curiosity, do you like your 213T? I'm looking at the 204T right now...
9.5.2006 10:46pm
Liam (mail):
Monitors and interference problems:
Flourescent lights, transformers (like power blocks for electronics, halogen lights, etc).

Try moving your computer to a different location and see if you have the same problem. If you do, you probably have a bad graphics card.
9.5.2006 10:46pm
DavidBernstein (mail):
Good suggestions. I like the 213T just fine, and I spend a lot of time in front of it. I highly recommend buying the biggest monitor you can comfortably afford, if you use the computer a lot.
9.5.2006 10:55pm
dan (mail):
LCD monitors should be relatively immune to the kind of magnetic interference caused by transformers and the like which often bedevils CRT monitors. A different possibility is a power issue called a ground loop. Make sure that the monitor and the computer (and any other devices connected to the monitor) are all plugged into the same outlet.
9.5.2006 11:09pm
Romach (mail) (www):
Let us know how it turns out.

I'll be buying 2 of whichever monitor I get. Right now it looks like 2 20" models, just haven't picked out the particular one yet.
9.5.2006 11:14pm
logicnazi (mail) (www):
The first thing I would try doing is moving the cord connecting the monitor to the computer around. If the interference changes (like the way it does when you move rabit ears around on the TV) then you are probably picking up some signal on the cord. Look to see what electronic devices it runs past. If this doesn't seem to be the cause try picking up the monitor and moving it around as far as your connecting cord will let you to see if you are picking up interferance in the monitor itself.

If neither of these work try connecting a different computer to the monitor but leaving it in the same place. It is entierly possible this is not interferance in your monitor but an error or interferance inside your video card. To output your video signal your video card needs to time it's signals very accurately to the rate at which the electron beam scans across the monitor (or pretends to do so for LCD monitors). If the output clock gets slightly skewed or has some regular error this could happen without interferance.

If you want future help it might be usefull to tell us if you are connecting your monitor with an digital able or the old analog ones. The old analog ones have all the pins in the cable while the new digital ones have the 'pins' in the two devices and the pins aren't just pins but flat little sticks.
9.5.2006 11:16pm
John Armstrong (mail):
Are the "waves" stationary, not moving back and forth? If so, check for magnets near your desk but not near your wife's.
9.5.2006 11:25pm
John (mail):
It's the NSA beaming energy to suck out the data on your computer. Duck!
9.5.2006 11:28pm
guy (mail):
It could also be a problem inside your case - say, a fan dying on your video card or chipset
9.5.2006 11:33pm
Tim Howland (mail) (www):
Wavy displays in an LCD aren't likely to be magnetic. The cables are shielded, and LCD's don't rely on electromagnetism to deflect electrons the way old CRT's do.

Likely culprits are a flaky cable, a loose pin in one of the vga connectors, or a dying video card. You may want to try messing with the scan rate and kicking it up from 60 to 70 Hz if the firmware allows it- even though LCD's don't actually scan, often the interfaces are reconfigured CRT boards, and it can make a slight difference.

Good luck!
9.5.2006 11:55pm
DavidBernstein (mail):
Logic, from your description, it's the old-fashioned kind. I'm going to sleep now, but tomorrow morning I'm going to try to connect my wife's monitor to my computer to see if that gets interference. If so, what do I do? Get a new video card? If her monitor works fine with my computer, I'll move the computer and monitor to another room, and see if they work there.
9.5.2006 11:56pm
DavidBernstein (mail):
I changed the refresh rate to 70, and that helped, and then to 75, and that helped more, but I'm still getting a some annoying interference. What does this mean?
9.6.2006 12:02am
DavidBernstein (mail):
I'm also going to try using a different monitor cable.
9.6.2006 12:03am
Sebastian (mail):

If your monitor and video card support it, try switching from a VGA style analog cable to a DVI cable (which is a bit wider connector). You'll probably get a better picture anyway, since the LCD monitors have to convert the analog signal they get from a VGA style connector to display on the LCD matrix anyway. With the digital DVI connector you don't have to deal with any of that crap, since DVI is a digital signal. I have a dual-head LCD setup here, but one is DVI and one is analog VGA, and I find the DVI to be a bit more crisp and the colors brighter.
9.6.2006 12:08am
roy (mail) (www):
I've had similar symptoms and traced them to the video card.

If one of the other computers has a removeable video card, move it to the dodgy system, perhaps with the help of a friendly geek. If the problem goes away, just buy a new card, they're cheap these days.
9.6.2006 12:18am
William M (mail):
It's most likely a problem with your video card (or integrated video). I have seen this happen on number of CRTs and LCDs and after a thorough investigation, it was discovered the video card was always to blame. Surprisingly, undating the drivers fixed the problem in a fraction of the cases so maybe it's worth a shot in your case.
9.6.2006 12:34am
Freddy Hill (mail):
Being a computer technician is easy. You just use the "swap technique": swap parts one at a time until the problem is fixed. In your case, the parts are the monitor, the cable and the video card. You ruled out the monitor, and possibly the cable, so what is left to try is the video card.

EM radiation is unlikely to be the cause; for one thing, the pattern would visibly change as you move the monitor and things around your desk.

Very old geek joke: Q- How does a computer technician fix a flat tire? A- He swaps wheels until the problem goes away.
9.6.2006 12:52am
Daryl Herbert (www):
If you have a laptop (or a 2nd computer), you should be able to plug your 213T into it as a secondary display. That will be an easy way to test your monitor/monitor cable.

Try it with your desktop computer running and not running, in the crazy off-chance that mysterious X-Waves from the Phantom Zone are to blame.

If the image comes out clean, you will at least know the problem is inside your CPU case (even though that's probably the last place you want it to be).
9.6.2006 4:13am

As it happens, I just upgraded my in-law's motherboard and case last week. The new motherboard had integrated video, and their old video card wouldn't fit in the new case. So I happen to have a spare video card floating around.

email me at thomas dot neville at gmail dot com if you discover you need a new video card.

9.6.2006 10:22am
sbw (mail) (www):
Adjust your tin foil hat?
9.6.2006 10:48am
"Very old geek joke: Q- How does a computer technician fix a flat tire? A- He swaps wheels until the problem goes away."
Actually, more likely he doesn't fix it. He just tells you it's "a hardware problem."
9.6.2006 2:51pm
H. Tuttle:
The video card is going bad.
9.6.2006 3:30pm
Randy Treptow (mail):
I run a large laboratory full of PCs. After some construction work that involved additional power outlets, we all noticed that 1/2 the monitors in the labs had a "wavy" look to them. After a lot of trial and error, we determined that the power outlets in the new part of the lab had something different in how the Neutral and Ground were routed. By running extension cords from the old outlets to the monitors, all of the waviness was eliminated. We went through another remodelling last year that involved the facility power again and this time we made sure that all of outlet wiring was done properly. No more wavy monitors!

Did you happen to have some wiring done recently? I know that you can buy a chap wiring tester at Home Depot or Lowe's that has 3 lights that plugs into the outlet and will show you if your Hot, Neutral and Ground are all correct at your outlet.

Hope this helps.
9.6.2006 3:42pm
Another idea: adjust the "phase" setting of the monitor. It could be the video card is overheating/getting old and shifting its signal phase, which can be corrected with that setting.
9.8.2006 8:42pm