Computer Interferes With TV

Old 06-24-02, 11:12 AM
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Computer Interferes With TV

I don't know if this is the right forum but this is my problem.When the computer is turned on it interferes with tv reception,usually with squiggly lines and or static.

I don't have cable so the tv has an antenna.I have an old house with mostly newer wiring but some old.I've tried moving the tv to the other side of the house from the computer but it doesn't help.

I have 3 channels(yes count em a whole 3)channels 3,5 and 9. It only interferes with 3 and 5.

Is this an electrical problem or am I barking up the wrong tree?
Old 06-24-02, 09:48 PM
bungalow jeff
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It is probably because the TV and computer are on the same circuit. Of course finding an outlet that is on a separate circuit where you would want the computer may lead you back here with another post.
Old 06-25-02, 06:49 AM
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Jeff is probably right, however it may be that your computer is simply putting out too much RF (radio frequency) interference. Modern PCs run at very high frequencies, and they can easily conflict with numerous other devices -- such as cordless phones, radios (especially AM), and TVs.

About the only thing you can do if it's an RFI problem is move the computer further away from the TV. You can also buy a new case and transfer the internals to it, but unless you're comfortable with building PCs I don't recommend that.
Old 06-26-02, 07:00 AM
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Thanks for the info but I don't think I will try changing my case.It doesn't matter where I move the tv there is still interference.Oh to have cable.
Old 06-26-02, 10:45 AM
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Did you try an emi filter? You can probably find them real cheap at Radio Shack.
Old 06-26-02, 11:08 AM
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Something doesn't sound right. Computer cases/chassis are grounded to prevent this kind of problem.

Try checking the ground connection on your case. The resistance between the case/chassis andthe ground prong of the cord should be very low. Ideally less then 1 ohm.
Old 06-27-02, 07:23 AM
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Well I don't have the equipment to check the ohms but I will try the emi filter.Thanks.
Old 06-27-02, 09:57 AM
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Try a continuity indicator then. This may only be a symptom of a larger problem.
Old 06-27-02, 10:22 AM
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There's something really strange going on there. RF interference usually happens in the same room, not in between different rooms. Unless you have a very weak TV signal, or a weak tuner you shouldn't notice it. You may also have a weak or non existant ground in your electrical system. That will allow more EMI to emit. All computer cases I know are shielded (made of metal), and no or very little EMI should get out on the supply line. Even that should be only evident on the same circuit, and if the ground is not there. I have a TV and computer in my room, and even with a regular antena I get no interference, even if I take the cover off. It's unlikely that all your outlets are on the same circuit. If you have another TV I would check if that works any differently. If you want to remove the RF pushed back on the line you can plug the PC through a APC battery unit. But I don't think that's the solution. You can easily check the ground with an outlet tester you can buy at any Menards/Home Depot/Radio shack. You just plug in and it wil tell you if the wiring is grounded, or reversed. You computer is plugged into a 3 hole, grounded outlet right?
Old 06-28-02, 06:45 AM
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Yes my computer is plugged into a 3 hole outlet and I do get interference on both tvs.

It may be a while before I can get an outlet tester because I live way out in the boonies, unless I can get one at the hardware store.

When I do get one if there is a problem with the ground I will post back.Thanks.
Old 07-12-02, 12:56 PM
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There are several periphials that could conceivably cause RFI to your television. Are you using an RF wireless keyboard?

I have had several instances where interference was caused to my computer, or other components. In one circumstance, I ended up running a wire from my computer's cabinet to a ground rod outside which corrected the problem.

It is most likely that you either have the computer and TV operating on the same circuit, or you are using an external device on your computer (USB devices, wireless devices etc.) that are not located inside the computer's case, and therefore are not "sheilded" for RF Interference.

Good luck!
Old 07-13-02, 04:45 PM
Mark Nolte
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This may be too easy.
Loose antenna connection? The TV may pick up the computer "interference" with the antenna completely disconnected, hence it is getting a stronger signal from the computer than the antenna. (If you had a HAM closeby, the TV may pick up the HAM radio, too. ...and blame the Amatuer Radio operator...)
The other item is to make sure the computer has a good ground. It really needs one in any circumstance. Unless you do daily backups, you may be living on the edge.
Third check is to make sure nothing is reflecting the weak signal at the TV. A large metalized object, such as a refrigerator, can make an innocent "leak" into an obvious problem. A mirror behind the TV?
While you're at it, make sure there is some sort of surge protection on the TV antenna wiring. If it's coax, a standard item is available. I don't know what you'd use for the flat, wide wire.

If your TV antenna is old, you may just have a corrorded connection. Wire is copper, the antenna parts are steel and aluminum. They all deteriorate in their own, special way. I wonder if just going up on the roof and spraying the antenna wires with WD40 changes things. If so, next trip up on the roof, redo the connection.
Old 07-15-02, 12:55 PM
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I have had this exact problem in with my Viewsonic 17" computer monitor. With my new Compaq 19" monitor (all other computer components the same) this does not occur. I can have my 17" monitor ON in the basement and it will interfere with my TV/VCR reception (antenna, channels 4 and 5 only) upstairs on the other end of the house. My computer behaved the same way in my old apartment too, so I know that it does not have anything to do with the wiring in my house.

Things I suggest to try:
-UPS that will filter voltage/neutral input (havent tried this)
-new monitor (worked for me)
-cable TV/satellite (also works)
-turning off your TV (or your monitor)

It has nothing to do with what circuit it is on (and definately not dependent on which breaker, they all tie back to the same circuit panel). I tried hooking it into a different phase on my power panel (each house has at least an "A" and a "B" phase). My TV was on the "A" phase and my Computer on the "B" Phase. It still had interference.

I suspect that my monitor puts some kind of noise on the neutral line of my power lines. All the neutral lines are connected together at the circuit panel no matter which phase they are on. This is the only reasoning I could come up with. I tried both rabbit ear antennas and powered ones. Both behaved the same way. If I watch a VCR tape on channel 4 it does not interfere. So there is something unique about antenna reception that causes this interference. Now that I have Cable TV it does not interfere with my TV upstairs. However, I have a small TV in my basement that does not have cable. It still behaves the same way (interference on channels 4 and 5) with the 17" monitor ON though. I still use my 17" and an old computer from time to time.

Hope this helped some.

Things that didnt work:
-antenna booster (powered, from radio shack)
-rabbit ears vs. powered RCA antenna
-moving the computer away from the TV
-different circuit breaker
-different circuit phase
-any type of surge supressor
-different frequency output to monitor from video card

I always wondered if my neighbors in my apartment complex ever had interference from it too... I'm guessing that most of them had cable though.

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