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Author Topic: My new house and EMI(?)
drunkennewfiemidget
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Icon 5 posted July 15, 2004 19:11      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
I need the help of some EMI expert/electronics geeks.

So, I finally got around to unpacking my basement and getting my computers, etc online. But I've run into one HELLUVA problem.

In my basement, ALL monitors/TVs develop this shaking problem. My 21" Sony Trinitron monitor, and my 20" Sony Trinitron monitor have developed a screen shaking problem in one particular corner of the basement.

I have a 17" AOC monitor that both developed a shake in that corner, aswell as a dark spot in the lower left and upper right corners.

So I moved all my monitors over to the opposite side of the room... they still shake! I moved them upstairs, and they still shake!

However, I know they survived the move OK, because I had them on upstairs before I brought them downstairs and they were perfect.

So I have a few questions.

A) What could cause this? EMI?
B) Is there any (inexpensive) way I can test this?
C) My projection TV is over in that corner now -- for the first 5 or so minutes it's on, the colour keeps jumping (as if someone's turned the brightness or contrast WAY up, and then back to normal in the span of about half a second.) After about 5 minutes, it goes away and works perfectly. Am I at risk of causing permanent damage to it over there?
D) Is there anything I can do to fix it short of moving stuff out of that corner? (I have limited space, so not being able to use that particular side of the room would be VERY detrimental to its use.
E) Even after monitors are moved out of that environment, they continue to shake. Degaussing makes it stop shaking for about 1 second, then it goes back. Is there anything I can do to fix this short of taking it in for repairs, or are they permanently screwed until I get them fixed?

Any help or even a point to some links to read up on my own would be appreciated.

EDIT: I've tested and ensured it's not the power source to any of the devices (I've plugged them into a UPS and then unplugged the UPS, so they ran directly off of the battery, as well as removed them from UPSes entirely). I've also tested the input source. The TV does its colour thing whether its on component 1 (hdtv digital cable), component 2 (playstation 2), composite (nes), or cable. The monitors also shake when the "monitor is functioning, no input source" is on them, and they are completely disconnected from the computer.

Posts: 4897 | From: Cambridge, ON, Canada | Registered: Jun 2004  |  IP: Logged
TheMoMan
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Icon 1 posted July 16, 2004 03:57      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
drunkennewfiemidget_______This sure sounds like EMI, now here are a few things to look for. Beause you are having these troubles in a basement, Do you have buried electric service (no overhead wires)? Are you near any of those Iron Giants that support High Voltage Wires? If the first two are no are you near an airport or Military base? Is the location in the house that is causing the most trouble near the main or a sub fuse box? Still no? Is the location under the refridgerator, or Freezer, or near the outside unit of the central airconditioning or furnace fan or any other fans? Still no, Then go to the main fuse or breaker box and turn off one breaker at a time untill you have found the at fault circuit, still no luck, you will then need some one with a sprectrum reciever to see what is causing the problem. I hope that I have givin you enough info to find and correct the problem, I doubt that you have hosed any equipment but it would sure be a bummer if you had to make a Farady cage for your electronics. This is clear on this Frequency. I fyou have more troubles e-mail me at

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drunkennewfiemidget
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Icon 1 posted July 16, 2004 04:14      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
Well that definitely helped.

The fuse panel is on the OPPOSITE side of the room where the EMI is the worst.. and the NEW location of the computers is where the fuse panel is. When I plugged all of my TVs and monitors into UPSes, they still shook.. as soon as I flipped the breaker to the basement, got a little better, but not perfect.

... when the EMI is removed from the picture, how long would it take a monitor to go back to normal?

And to answer your other questions:


Buried electric service? Yes. It comes in on the opposite side of the basement.

Near iron giants? No.

Near an airport? Not really. Nearest airport is about 15-20km away.

Is the troublesome part of the basement near the fuse box? No. It's on the opposite side of the room.

Is the location under the refridgerator? Yes it is. At least on the same side of the wall.

Fuse fan/mainfurnace fan, etc? No.

But if removing the EMI would immediately fix the problem, it's none of those because I have flipped off the MAIN breaker to the house and let the monitor run on UPS juice, and that didn't clear it up.. it helped, but didn't fix it.

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CommanderShroom
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Icon 1 posted July 16, 2004 04:31      Profile for CommanderShroom     Send New Private Message       Edit/Delete Post   Reply With Quote 
Ignore this post (screwup)

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quantumfluff
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Icon 1 posted July 16, 2004 06:28      Profile for quantumfluff     Send New Private Message       Edit/Delete Post   Reply With Quote 
I also think it's EMI. I discovered that if I put a monitor within 6 feet of the power feed into the house, it get's all messed up. This makes the corner of my house where the cables come down through the meter and into the basement useless. I find it's not the fuse box that's the problem, it's the transmission feed.

Get a compass and see what readings you get in the bad spots. If it is pointing wildly away from north, then you're in trouble.

I don't see how the shaking could be persistant after you move them, but you may find that the EMI is really rampant in your house. If so, the solution might be to build a big Faraday cage for your office, like Harry Caul's. Of course, you can probabaly only do that if you are unmarried, or simply eccentric.

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Doco

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Icon 1 posted July 16, 2004 08:07      Profile for Doco   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Sounds like EMI to me too. If you shut down the offending circuit the problem should go away immediately.

If you have already tried shutting down the main breaker for the house and still have a problem - then it is something outside that is causing you grief. I've never personally had problems with outside the home problems - but have heard of people that did.

I might try a different location or two while using the UPS and the power to the house is shut down. Usually near the fuse box is where the power comes in and that gives the most problems. Maybe you have more than one source giving you problems.

Look outside for really close cell phone towers (sometimes disguised in church steeples or on water towers) or microwave towers. A radio/tv transmission tower can cause problems for a fair distance.

Try asking the neighbors is any of them have problems with their TVs. They may know of some source of problems.

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ooby
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Icon 1 posted July 16, 2004 09:41      Profile for ooby     Send New Private Message       Edit/Delete Post   Reply With Quote 
Aside from aforementioned posssible culprits, you should also investigate other motored appliaces suchs as washers and dryers, and sub pumps. A hackeresque (but not necessarily the easiest) way would be to use your sound card as an oscilloscope. You can check for 60-cycle hum (is it 50 cycle in Canada?) among other sources of interference. You won't be able to measure the magnitude because soundcards have automatic gain control, but you can measure from 0 to 44KHz.

Also check your grounding. I would first make sure the computer is nicely grounded. Then proceed with the circuit breaker elimination and ground any suspicious equipment.

--------------------
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drunkennewfiemidget
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Icon 1 posted July 16, 2004 11:16      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
Thank you muchly for all of your input. This weekend shall be devoted to attempting to locate and isolate the culprit. If I can at least figure out WHAT's causing it, then I can decide what I'm going to do about it.. a giant faraday cage doesn't sound like a half bad idea though. [Wink]

I'll let you all know if you care to what it turned out to be.

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quantumfluff
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Icon 1 posted July 16, 2004 15:51      Profile for quantumfluff     Send New Private Message       Edit/Delete Post   Reply With Quote 
Oh yeah. I forgot about ground fault and polarity problems. Go get one of those electrical testers from your local hardware store and check every outlet in the house. You may find that phases are reversed all over the place.
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MrMachineCode
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Icon 5 posted July 17, 2004 07:08      Profile for MrMachineCode     Send New Private Message       Edit/Delete Post   Reply With Quote 
Would a Farady cage really work for low frequency magnetic fields (as opposed to radio waves)? You would think that if the frequency is low enough and stems from a powerful magnet (like a large motor) that a Faraday cage would barely affect it. If it's a magnetic problem wouldn't you instead need magnetic shielding to absorb it, like a wall of iron ferrite 3 feet thick?
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MrMachineCode
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Icon 6 posted July 17, 2004 07:10      Profile for MrMachineCode     Send New Private Message       Edit/Delete Post   Reply With Quote 
Maybe you're near a secret government anti-newfie defense testing site.
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drunkennewfiemidget
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Icon 1 posted July 17, 2004 11:01      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
That's a distinct possibility, but I don't think it's the case. [Wink]

I've found the issue... it's the circuit that runs downstairs.. I'm guessing a wire is exposed behind the wall or something.. now the fun question... how the fsck do I fix it? [Razz]

If I call the landlord, will they do anything about it?

Hrm.

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Alan!
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Icon 1 posted July 18, 2004 02:44      Profile for Alan!     Send New Private Message       Edit/Delete Post   Reply With Quote 
Good detective work drunkennewfiemidget! I thought it would have been electrical, and most probably earthing, given that the problem persisted even when you knocked out the power (earth remains).

So, time for rewiring! The cheap temporary fix of course is to run a big long extension lead down to the basement. Make sure you're using circuit breakers and powerconditioners too!

--------------------
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CommanderShroom
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Icon 1 posted July 18, 2004 05:50      Profile for CommanderShroom     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by drunkennewfiemidget:

If I call the landlord, will they do anything about it?

Hrm.

newfie,

I don't know how the laws are out there. I am assuming they are similar. Your landlord should be resposible for all repairs for the house so long as it isn't you screwing things up. I think you should try with him/her first and then go from there.

CommanderShroom

--------------------
Does he know our big secret?
Has one of us confessed?
'Bout the wires circuits and motors
Buried in our chest

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MrMachineCode
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Icon 3 posted July 18, 2004 07:32      Profile for MrMachineCode     Send New Private Message       Edit/Delete Post   Reply With Quote 
Grounding is important especially with computer stuff. One time I actually measured a steady shorted current of 500 mA and an open circuit voltage of 12 volt between the case of a computer that wasn't properly grounded and the rest of my network which was. It may have been a faulty power supply in the computer; in any case, if I hadn't grounded that case before connecting it, I would have been putting 500 mA through my ethernet cable.
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Number 2608
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Icon 1 posted July 18, 2004 08:40      Profile for Number 2608     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by MrMachineCode:

One time I actually measured a steady shorted current of 500 mA and an open circuit voltage of 12 volt between the case of a computer that wasn't properly grounded and the rest of my network which was.

I went on an electrical testing course last week. According to the guy running it some computer equipment is actually designed to use the earth connection as a return path for small voltages/currents.
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TheMoMan
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Icon 1 posted July 19, 2004 10:58      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
drunkennewfiemidget________Well if the fridge is the culprit then I guess its no cold beer, just kidding. Yes in time your monitor will return to normal or you can go and buy a degaussing coil and follow the directions. I doubt that the landlord will care that your monitors don't work correctly all he is interested in is you paying the rent I doubt he would even pay for an electrican to look for the problem. Could you get an old bank vault to put your stuff in that should shield it.
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drunkennewfiemidget
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Icon 1 posted July 19, 2004 11:42      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
heh. Yea, excuse me while I purchase a bank vault.

How are degaussing coils different from the degauss button on a monitor? Are they?

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TheMoMan
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Icon 1 posted July 20, 2004 09:54      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
drunkennewfiemidget_____Most CRT monitors have a degaussing coil built arround the front mask of the tube, during power on startup the coil is turned on for a few seconds to knock out left over magnitism from the previous use. Degausing coils that you can purchese are much more powerfull, than the built in ones. Do you have any large speakers near your monitors?

--------------------
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5848 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
drunkennewfiemidget
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Icon 1 posted July 20, 2004 10:50      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
Nope. Nothing anywhere near it that could cause EMI... the computer it's hooked up to is > 4 feet away, and the UPS is about 3 feet away from it on the floor.

The layout of everything on the desk is the exact same as my old house where it worked flawlessly. The only difference is where it is in the house.

It does the shake thing in every corner of the basement.

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ooby
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Icon 1 posted July 20, 2004 11:36      Profile for ooby     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by Number 2608:
I went on an electrical testing course last week. According to the guy running it some computer equipment is actually designed to use the earth connection as a return path for small voltages/currents.

Here in the states, using earth ground as a return path is exactly the kind of thing the National Fire Protection Agency doesn't want.

But I think electricity might work a little differently in other countries [Wink]

--------------------
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drunkennewfiemidget
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Icon 1 posted July 20, 2004 11:54      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
Well here's the fun thing I've gathered so far:

it's only my monitors now. the tv, it seems, only has an issue when it's FRESHLY plugged in. once the tv's plugged in and has been plugged in for more than about an hour, the colour issue goes away entirely.. might be entirely unrelated.

when I flip the house's main breaker and let the monitor run off the ups, it fixes it SOMETIMES. I thought it was the circuit down there, but as it turns out, it only helps sometimes.

I've learned that it's worse during sunlight, but when it's dark, it's almost completely eradicated.

I'm so confused by all of this that it hurts.

Maybe I'll just say fsck it and buy all new LCD monitors for my basement. [Big Grin]

Lets all just conclude that my house is possessed and move on.

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Number 2608
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Icon 1 posted July 20, 2004 12:14      Profile for Number 2608     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by ooby:

I think electricity might work a little differently in other countries

We have about twice as much here in the UK but it is 17% less frequent.
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TheMoMan
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Icon 1 posted July 20, 2004 16:55      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
drunkennewfiemidget______Now the telling prose, it is worse in the daytime. I would really check for radio or TV station towers near where you live, most stations run more power during daylight hours to ensure that they cover thier intended coverage area, during the evening and at night they reduce power so that they do not interfer with other stations out side of thier area.

--------------------
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


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The Famous Druid

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Icon 1 posted July 20, 2004 16:58      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by drunkennewfiemidget:
when I flip the house's main breaker and let the monitor run off the ups, it fixes it SOMETIMES. I thought it was the circuit down there, but as it turns out, it only helps sometimes.

I've learned that it's worse during sunlight, but when it's dark, it's almost completely eradicated.

Hmmmm, worse during the daytime eh?

You don't happen to have any neighbors with air-conditioners do you?

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