Computer Causing TV Interference

December 10, 2005 at 15:16:11
Specs: Win 98SE, 2.8 Ghz / 1022 Mb

I just had a new power supply installed. An Apex/Allied 300 watt ATX. Now my computer is causing interference on channel 4 on all my TV's. The interference shows up as horizontal thin white flickering lines. I am using an old computer power cord, and wonder if maybe that's the problem. The same computer, with it's original power cord (which I have lost) and a 350 watt Okia power supply didn't cause any interference. If it's not the power cord, where should I look?

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December 10, 2005 at 15:33:01

Cords cost about a buck.

Is your television connected to cable, or are you receiving by means of an aerial? Power supplies and vidcards will put out quite a bit of RF noise - shouldn't be a problem unless you're not on cable. If that's the case, I'm not sure that there's any easy solution

Resist the temptation to close your request for help with semantically-null questions like “Can anyone help me?”

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December 10, 2005 at 16:22:14

You're right, power cords are cheap enough - I'll try a new one. My TV reception is from an antenna on a tower outside. The computer is on a circuit by itself and I tried plugging it in around the house with no change.

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December 10, 2005 at 16:58:07

Yeah - you can try another cord, but I'm doubtful if that would make a difference - the new PSU is likely putting out noise at a different (and more inconvenient) frequency than old one. I experienced much the same thing when I wasn't connected to cable - in order to watch certain channels the computer(s) had to be off.

Being on a different outlet or more distant from the set may help, but it sounds like you are already doing that. Broadcast signals are subject to all sorts of things, possibly connecting an RF filter on the antenna output could be beneficial, but maybe not

Resist the temptation to close your request for help with semantically-null questions like “Can anyone help me?”

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Related Solutions

December 10, 2005 at 17:07:56

I have a job to see how a cable could cause this. More likely that your new Power Supply is either defective or has a design weakness.


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December 10, 2005 at 19:02:43

Power supplies are REQUIRED by the FCC, in the US, to have adequate filtering at the power line connection, and the power supply CASE must be shielded, as well as proper ferrite cores on the various leads to cut down radiation on the DC leads.

Now, one question---Do you have your computer properly installed, in an approved case, with ALL the shields in place, including the factory shields over the empty drive bays, the unused card slots?

Do you have an (illegal) case with a big 'ol huge winder in the side you you can "see?"

Do you have the case assembled?

If all the above is in place, I'd be for either getting a replacement supply, or else even a different brand.

I'm a radio amateur, and am constantly bombarded, in this day, with radiation from every thing imaginable on HF radio.

Lamp dimmers, cell phone chargers, HP printer supplies, laptop supplies, routers, cable modems, and even one of my monitors when it is plugged in, but shut off.

TV sets, even processors in kitchen ranges and microwave ovens, can radiate interferance. Of course there are street lights, flourescent, and othe arc-discharge lamps. The infuriating Christmas tree blinkers make noise, and so do some solid state furnace controllers.

If you have radiated noise bad enough to get into a TV, it's bad. I'd be for getting rid of that supply. It's even possible that it has some electrical problem that could lead to more serious troubles.

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December 11, 2005 at 11:05:50

Well thought out post - we have things in common (see PM I sent you).

I've just had a thought. If the earth lead (ground in USA? - I'm UK) is open circuit this might just cause the problem, so I change my mind a little. Absence of case earthing/grounding is also a possibility. Are you handy with a multi-meter?

If this is not the problem then you might care to persue a very long shot. Take out your speaker leads and then try. If this helps I might be able to suggest a rather crude work-around.


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December 12, 2005 at 16:26:24

Plugged into a GOOD surge suppressor???

Internet search engines are your friends.

Morpheus: There is a difference between knowing the path and walking the path. "The Matrix"

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December 14, 2005 at 10:50:55

Well, I checked out everything that was recommended and it looks I'm going to try a new power supply.

I too am a radio amateur and familiar with all sorts of interference, but this has me stumped. I've got a regulation case with all the shields in place. Today I separated all the cords coming into the computer so that nothing lays over anything else, but no difference. I tried a new power cord with no change.

I am however using an adapter to run my PS2 keyboard from a USB port. It seems when I move the adapter I see changes in the TV. Guess I'll pick up a USB keyboard too.

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December 14, 2005 at 11:28:54

Did you try taking the speaker leads out? I should have said "at the computer end". I've sometimes known them to radiate interference and if so there might be a way round it.


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December 14, 2005 at 14:32:10

I tried disconnecting the speakers at the computer - no difference. The only thing that seems to have any effect on the interference is moving that darn PS2-USB adapter around, so it's got to go.

When I replaced the power supply, I sent the old one in, as it was still under warranty. I'll try switching it out as soon as the replacement arrives. I know all power supplies are supposed to be interference free, but I have my doubts.

Thanks for all the input, it's been a learning experience.

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December 14, 2005 at 15:47:39

Fine, that was a very long shot anyway. I expect it's a dodgy PS. Thx for popping back, hope all goes well.


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December 15, 2005 at 19:51:33

hi I have a problem too, I have my computer connected to with audio and video to my technics av reciver, because my tv has only one tv in, so i have de dvd, the computer and the digital cable to the reciver but there is a lot of interference, and the only way to aboid it is to unplugge the computer or the cable of tv cable, what can i do, is it a problem of the ac power of the computer, or is it a problem of the reciver????

michael jordan

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