Can flourescent lights interfere with monitors?

[tedoff]

Hi,

There's a section of my office with a soffit that comes about 5-6 inches below the normal drop ceiling. Mounted under that soffit are a bank of surface mounted flourescent lights, which are unlike the recessed light housings in the regular drop ceiling.

Now it appears that all the PC monitors and dumb terminal monitors under that bank of lights have a "wobbling" interference effect, like they're at the very end of a degaussing.

Can the EM flow within the flourescent bulb tubes interfere with the monitor tubes for the PCs and dumb terminals?

Thanks!
J

 

[KIDA1973]

I would imagine that it could...why not turn out the lights and see if the "wobbling" goes away?

Good luck!


Matthew P Janes
Computer Network Support Technician
Boise State University Student Union
Boise ID 83725

 

[rblue]

The EM flow wouldn't be coming from the tubes themselves, but from the ballast in the fixtures.

One really good indicator is if you hear a buzzing sound coming from the light fixtures.

 

[tedoff]

Hi,

Thanks for the responses! I unfortunately can't turn off the lights to test my theory because I'd have to shut off the whole first floor of my building. I could look at it after hours some day, though.

Anyway, this type of interference, has it been documented anywhere that anyone knows of?

Thanks,
J

 

[KIDA1973]

I personally have seen this type of interference, and it has been caused by two different problems, one being flourescent lighting fixtures. There is one other possibility, and that is that the power source to the machines in that area of the room may be "dirty" - I know it is a long shot, but I have seen power plugs where ANY monitor plugged in had "wavy" effects on the screen as described, like it was at the last stage of degaussing. You might want to play with the refresh rates on the monitors also and see if you can get a more stable picture that way...

Another way to test it wether it is the power source or lights would be to run an extension cord from a power plug OUTSIDE the problem area and plug in a known working (non wobbly) monitor INSIDE the problem area. If you still get the wobble, it is probably the lights. You could also do the exact opposite and plug the extension cord in at a power plug INSIDE the affected area, and plug a know working monitor into it OUTSIDE the effected area. If you still get the wobble, I would look at the power source. If not, it must be the lights.

As always, good luck.


Matthew Janes

Everything in its right place...

 

[studentgrant]

just a thought are there any other lights close by? have come across a problem whereby desktop halogen lamps can cause the same problems (due to the power transformer). also get the maintenance boys to remove the tubes whilst they are on (yes it is reasonably safe to do)

 

[diogenes10]

Large electrical panels near office area will create that problem too.

 

[tedoff]

Thanks to all for the suggestions and the info!

 

[mosesashes]

Any source of electricity close to the moitors will cause this effect, I used to work in a manufacturing facility with lots of high voltage devices. Monitors near these sources were always hard to look at for a long period of time. Eventually the monitor becomes toasted because of this and needs tp be replaced if it is to be used to nay degree. We used to actually rotate monitors around so that none stayed in any one place to long. It was a bit of a pain but saved the cost of replacing monitors.

 

[killowhat]

dimmer switches, flourescent lighting, dirty power, portable devices that are plugged in on the same circuit as your pc, such as, coffee makers, hot plates, heaters, fans, vaccum cleaners, floor buffers. etc. you should be plugged into an isolated ground circuit.