Air Conditioner Causes PC Monitors to Vibrate

I had the vibrating problem with 2 monitors standing next to each other on my desk. I placed magnetic shielding (striped from an old HP stiffy drive) between them to eliminate the transmission of signals via Tesla waves.

What kind of vibration are you talking about? Is it physical vibration? Are the PC monitors displays wiggling/shimmering, have horizontal lines on them, have snow or whatever on them? A better description could be important for us to give you a good answer.

regards,

Vulcan

The PC monitors displays wiggling/shimmering

CRTs waver because of external, alternating magnetic fields that combine with their own vertical deflection fields and also produce a slight horizontal shift. The observable effect is usually the result of a frequency beat between both fields. For example, if the vertical refresh rate is 70 Hz and the interference oscillates at 60 Hz, you'll have a beat of 10Hz. In the case both frequencies are nominally the same (for example, two CRTs back-to-back, or close to one another, or a CRT with 60 Hz refresh rate interacting with the grid frequency) the beat will result from the small differences between the two actual frequencies, and may be anywhere from 1-2 Hz to practically 0 Hz (very slow wavering). LCDs are stable because their operation doesn't involve magnetic fields.

This happens, as said, when two CRTs are placed very close, but also when any source of alternating magnetic field is in the proximity, specially trafos and motors. I think that in your case the magnetic field of the AC wiring is the culprit. Maybe a poor wiring has something to do, too.

As Hendrik correctly suggests, you can get rid of this effect by (magnetically) shielding the monitors. Other approaches may include relocating the monitors (a little farther from the interference source), and/or shielding the AC conductors.

Dear,

This is clear sign of electro magnetic induction interference. Most probably, Electronic earth may not have been provided to each monitors. Which is a requirement of a seperate earth.

Stabilizers / ups system may not be having a seperate earth. This is also an essential requirement.

In addition to above, if problem persists, shielded cables may be added to the power supplies of each monitors & PCs.

As Harry said This is clear sign of electromagnetic induction interference. Are the monitors close to a transformer or electrical room? temporarily use an extension cord and plug them into another plug. Relocate them to another location and see if you get and results.

I agree with Harry and Hendrik say, if you want to be sure check the noise on the power line when the air conditioner is on with an oscilloscope, and it can even be that the air conditioner is badly earthed

Very simple, your power source is near overloading and can't give you a clear electric power. if the a.c. is off everything is right because the electric systeme is not overasked for power. your customer will have to put a second breaker only for the a.c. the best would be to put it on a phase and the rest of the electronic on a seperate phase. now you should know that phases should always be as equal as possible. and why the standart screen are flickering but not the lcd is simply that they're more sensible due to their way of functioning. What your company can do to overcome this problem if they don't want to remake their whole electric distribution is to plug every single screen that flickers on an ups Battery this will have as effect to clean the current since it is the battery that gives a constant charge. Even better if they loose electricity it will still work. Don't listen to all those who talk about earth magnetic field they're lost in their high university book. what I'm telling you is basic stuff that works.

you are dead on.

Dear Hanif, Please ensure U'r supply is capable of taking your A.C LOAD ( no abnormal drop in voltages while A.C Plant is "ON"),if not seprate the A.C load from the computers by new cables to avoid Voltage drop and EMI/RFI. Ensure electrical earthing of A.C Unit and Compressor and proper earthing of computer supply.You can also provide EMI/RFI FILTERS for individual P.C'S Hope this will give U results. If U have solved U'r problems thru' this forums suggestions,please send u'r reply so that others will also get to know abot the solutions to such types of problems. Nagesh Chennai - INDIA

If the airconditioner (outdoor unit) is a invertor type, check the filters, powered the invertor plate - these filters not working properly, and / or add filter in power suply line to this unit - the IGBT Modul return to power suply line a good many impulse noises.

If the airconditioner is a classic type - use a shielded cabels.