Electrical Panels + LCD's = ?

Eomer · 03-17-2005, 12:35 PM

Long story short, we just replaced all the workstations in our office. All of the monitors were good, cept for one guy's office where I had noticed it sometimes shimmered. It's about 5 years old, a 17" CRT. I noticed that it was doing that a year ago, but the guy is computer retarded and I've only ever observed him using it to play Solitaire (which I promptly removed the shortcut for). New guy is now moving into his office, and with the replacement of his tower I was going to get a new monitor. With the old one hooked up, the computer strangely enough was exhibiting some very odd behavior, running very slowly, icons flickering on and off etc.

The computer tech dude who's been doing all the work thought there might be something wrong with the computer itself, but then when we hooked up a different monitor to it the problems went away. So bizarrely enough somehow the monitor was fucking with the computer. I didn't even think that was possible, but hey, learn something new every day.

So I went and got a new 17" CRT, and when I first installed it it seemed fine. Then the guy rearranged his desk a bit, and wanted me to show him something on the computer. Right away I noticed the goddamn shimmering was back, on a brand new monitor. After checking his desk for any large magnets or motors or anything, it hit me that our building's electrical panels are directly on the other side of that wall, so basically within 6" of where the monitor is. The old monitor might actually be perfectly fine, after all (haven't checked). Considering the new one was like 150CDN and the store is kind of a fly by night operation, it's not worth returning the monitor, we'll just use it elsewhere.

So my question is, do LCD's get affected by magnetic fields? The guy is going to see if he can rearrange a few things on his desk and move the monitor, I don't imagine that it will need to be moved very much, good old inverse cubic functions and all. But in the event he can't, would a LCD be immune to that? I am not so familiar with exactly how they work, but my impression is that they don't have nearly as much to do with charged particles and magnetic fields and electrons like a CRT monitor does.

Anyone had an experience like this before?

Haldin Darconis · 03-17-2005, 02:25 PM

Generally speaking, LCDs are less likely to "shimmer" due to electrical problems or magnetic fields. There are several reasons for this.

First, the pixels on an LCD screen tend to stay illuminated longer than the phosphors on a CRT. This means a very brief fluctuation that can be seen on a CRT might be unnoticable on an LCD, even though the fluctuation still would technically be there.

The bigger reason for this is, as you said, because "they don't have nearly as much to do with charged particles and magnetic fields and electrons like a CRT monitor does." A CRT has an electron gun that sends electrons from the back of the tube to the front. This causes phosphors on the front of the screen to become excited and display the image. It's easy to see how minor electrical fluctuations could throw this system off and cause problems, especially since this electron beam is guided by an electromagic (usually called a "steering coil") within the monitor. However, LCDs basically work like stained glass. They have a light source behind the screen that shines through a screen that consists of tens of thousands of little cells. These cells contain liquid crystals that, when a charge is applied, only allow certain colors of light to pass through.

LCDs are basically hard-wired systems where everything is locked in place. CRTs have to make "leaps of faith" from cathode to anode to the screen.

You said you hooked up another monitor and it was fine, but then when you actually replaced the monitor the problem was back. It may be a problem with the computer. I would suggest, if possible, setting up an entirely different computer and monitor in the office to see if the problem shows up. If the issue doesn't occur with a new system, then the problem most likely is either the monitor (doubtful, since you've tested a few) or is coming from the computer iteself. My first guesses would be either power supply or video card if this is the case. However, if it persists with a new setup, the problem is almost definitely electrical in the office.

I've been in similar situations. For example, I had an area of a building with less-than-reliable electricity where monitors would flicker and shimmer. They wouldn't fix the electrical problems, but one solution (besides an LCD) was to get a Line Conditioner. These basically force the incoming electricity to behave nicely. This can also extend the life of electronics hooked up to this questionable power. Tripplite makes some basic ones that seem to do a pretty good job.
( http://tripplite.com/products/produc...productID=2010 )

Finally, this can be caused by electrical noise in the circuit. Sometimes another device (I've found laser printers can often be the culprit) plugged into the same surge protector or even just another outlet on the same circuit can pollute the electricity and cause some sensitive equipment to behave oddly, including shimmering on a monitor.

Eomer · 03-17-2005, 05:12 PM

There's two separate problems. There's the shimmering on the screen, which with the new monitor will only happen if the refresh is set higher than 60hz. At 60 there isn't any noticeable shimmering, but I'm going to move it anyway as there is definitely an issue at 75 and 85. That issue is still around. And I don't feel like taking the chance that the magnetic field is going to damage the monitor or computer long term.

The other issue only happened with the old monitor, which somehow was causing the computer to run really slowly occasionally, things would flicker on the screen (the picture itself was fine, but icons would flash on and off, was strange) and other really strange things. Since then there's been two other monitors attached and it's been fine with either of those, even if they are having the shimmering problem as mentioned above. I really have no idea how it would be possible for a monitor receiving interference to cause a computer to run slower, but that was definitely the problem. It's gone now. The tech guy said he's never seen anything like it before.

In the end we are just going to move the computer and monitor a few feet away, that should be more than enough distance. The previous computer and monitor were in that location for 5+ years and only recently did the problem pop up, I think just because the monitor was moved just a few inches closer. Funny how stuff like that works.

Hippos II · 03-17-2005, 07:08 PM

Quote:

The other issue only happened with the old monitor, which somehow was causing the computer to run really slowly occasionally, things would flicker on the screen (the picture itself was fine, but icons would flash on and off, was strange) and other really strange things. Since then there's been two other monitors attached and it's been fine with either of those, even if they are having the shimmering problem as mentioned above. I really have no idea how it would be possible for a monitor receiving interference to cause a computer to run slower, but that was definitely the problem. It's gone now. The tech guy said he's never seen anything like it before.

oddly enough I had this exact same problem with my last monitor. it flickered like crazy right before I bought a new one, and would make both my computer and internet connection (wtf?) run much slower than usual (internet connection would lose like 40kbps off downloads). when I went out and bought a new viewsonic and plugged it in, the problems were gone.

findar · 03-20-2005, 07:05 PM

you downloaded a ghost.

i suggest the latest ghostbusting software, i think macafee has something out now.

The Bog · 03-20-2005, 07:51 PM

Quote:

Originally posted by findar
you downloaded a ghost.

i suggest the latest ghostbusting software, i think macafee has something out now.

He's a sailor in New York, we just need to get him laid.

03-17-2005, 12:35 PM	#1 (permalink)
Eomer Registered User Join Date: Feb 2002 Posts: 8,888 +4 Internets	Electrical Panels + LCD's = ? Long story short, we just replaced all the workstations in our office. All of the monitors were good, cept for one guy's office where I had noticed it sometimes shimmered. It's about 5 years old, a 17" CRT. I noticed that it was doing that a year ago, but the guy is computer retarded and I've only ever observed him using it to play Solitaire (which I promptly removed the shortcut for). New guy is now moving into his office, and with the replacement of his tower I was going to get a new monitor. With the old one hooked up, the computer strangely enough was exhibiting some very odd behavior, running very slowly, icons flickering on and off etc. The computer tech dude who's been doing all the work thought there might be something wrong with the computer itself, but then when we hooked up a different monitor to it the problems went away. So bizarrely enough somehow the monitor was fucking with the computer. I didn't even think that was possible, but hey, learn something new every day. So I went and got a new 17" CRT, and when I first installed it it seemed fine. Then the guy rearranged his desk a bit, and wanted me to show him something on the computer. Right away I noticed the goddamn shimmering was back, on a brand new monitor. After checking his desk for any large magnets or motors or anything, it hit me that our building's electrical panels are directly on the other side of that wall, so basically within 6" of where the monitor is. The old monitor might actually be perfectly fine, after all (haven't checked). Considering the new one was like 150CDN and the store is kind of a fly by night operation, it's not worth returning the monitor, we'll just use it elsewhere. So my question is, do LCD's get affected by magnetic fields? The guy is going to see if he can rearrange a few things on his desk and move the monitor, I don't imagine that it will need to be moved very much, good old inverse cubic functions and all. But in the event he can't, would a LCD be immune to that? I am not so familiar with exactly how they work, but my impression is that they don't have nearly as much to do with charged particles and magnetic fields and electrons like a CRT monitor does. Anyone had an experience like this before?

03-20-2005, 07:05 PM	#5 (permalink)
findar Registered User Join Date: Aug 2002 Posts: 3,161 -2 Internets	you downloaded a ghost. i suggest the latest ghostbusting software, i think macafee has something out now. __________________ -its clobbering time

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread:

03-17-2005, 02:25 PM	#2 (permalink)
Haldin Darconis Me. Join Date: Jun 2003 Posts: 140 +0 Internets	Generally speaking, LCDs are less likely to "shimmer" due to electrical problems or magnetic fields. There are several reasons for this. First, the pixels on an LCD screen tend to stay illuminated longer than the phosphors on a CRT. This means a very brief fluctuation that can be seen on a CRT might be unnoticable on an LCD, even though the fluctuation still would technically be there. The bigger reason for this is, as you said, because "they don't have nearly as much to do with charged particles and magnetic fields and electrons like a CRT monitor does." A CRT has an electron gun that sends electrons from the back of the tube to the front. This causes phosphors on the front of the screen to become excited and display the image. It's easy to see how minor electrical fluctuations could throw this system off and cause problems, especially since this electron beam is guided by an electromagic (usually called a "steering coil") within the monitor. However, LCDs basically work like stained glass. They have a light source behind the screen that shines through a screen that consists of tens of thousands of little cells. These cells contain liquid crystals that, when a charge is applied, only allow certain colors of light to pass through. LCDs are basically hard-wired systems where everything is locked in place. CRTs have to make "leaps of faith" from cathode to anode to the screen. You said you hooked up another monitor and it was fine, but then when you actually replaced the monitor the problem was back. It may be a problem with the computer. I would suggest, if possible, setting up an entirely different computer and monitor in the office to see if the problem shows up. If the issue doesn't occur with a new system, then the problem most likely is either the monitor (doubtful, since you've tested a few) or is coming from the computer iteself. My first guesses would be either power supply or video card if this is the case. However, if it persists with a new setup, the problem is almost definitely electrical in the office. I've been in similar situations. For example, I had an area of a building with less-than-reliable electricity where monitors would flicker and shimmer. They wouldn't fix the electrical problems, but one solution (besides an LCD) was to get a Line Conditioner. These basically force the incoming electricity to behave nicely. This can also extend the life of electronics hooked up to this questionable power. Tripplite makes some basic ones that seem to do a pretty good job. ( http://tripplite.com/products/produc...productID=2010 ) Finally, this can be caused by electrical noise in the circuit. Sometimes another device (I've found laser printers can often be the culprit) plugged into the same surge protector or even just another outlet on the same circuit can pollute the electricity and cause some sensitive equipment to behave oddly, including shimmering on a monitor.

03-17-2005, 05:12 PM	#3 (permalink)
Eomer Registered User Join Date: Feb 2002 Posts: 8,888 +4 Internets	There's two separate problems. There's the shimmering on the screen, which with the new monitor will only happen if the refresh is set higher than 60hz. At 60 there isn't any noticeable shimmering, but I'm going to move it anyway as there is definitely an issue at 75 and 85. That issue is still around. And I don't feel like taking the chance that the magnetic field is going to damage the monitor or computer long term. The other issue only happened with the old monitor, which somehow was causing the computer to run really slowly occasionally, things would flicker on the screen (the picture itself was fine, but icons would flash on and off, was strange) and other really strange things. Since then there's been two other monitors attached and it's been fine with either of those, even if they are having the shimmering problem as mentioned above. I really have no idea how it would be possible for a monitor receiving interference to cause a computer to run slower, but that was definitely the problem. It's gone now. The tech guy said he's never seen anything like it before. In the end we are just going to move the computer and monitor a few feet away, that should be more than enough distance. The previous computer and monitor were in that location for 5+ years and only recently did the problem pop up, I think just because the monitor was moved just a few inches closer. Funny how stuff like that works.