Electrial Question

Lately I have been having some problems with some electrical interference. Occasionally through my computer speakers I get some popping noises. I checked the outlets with one of those plug in wiring fault testers. No problems there.
Anyone know what could be causing this?
Thanks,
Bill    
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Likely computer related if another circiut does not fix the problem, possibly a flourescent light or motor switching on off nearby or on the same circuit. The computers power amp could be failing.
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popping sounds more like dirty connections than electrical interference, which would be more likely to cause a continual hum. how are the speaker wire connections? if they are dirty a little contact cleaner will fix them right up.
If you wanted to go nuts you could shut off all the circuits in your house but the one your computer is on and shut off every device on that circuit except the computer and see if the popping still occurs. If it does that pretty much rules out interference.
ml
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After I wrote this reply. About an hour later the popping from the speakers happened again. I used a multimeter on one of the outlets to monitor any fluctuation in current. And there was none.
The strange part about this is that it only started about a week ago. I might check all the connections is the receptacle boxes and the circuit breaker that supplies the bedroom current. This circuit breaker only supplies this particular bedroom and no other circuits.
Thanks again,
Bill
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The existence of or a missing earth ground cannot be measured at a wall receptacle. The only effective method of verifying earth ground is inspection. Each incoming utility must have a dedicated wire that connects to the earth ground rod (or whatever is being used as the earth ground). The earth ground wire that comes from circuit breaker box must use same earth ground that telephone interface box connects to AND that cable shield connects to. Code demands that each utility earthing wire be less than 20 feet. You want each wire to be less than ten feet.
Will this solve your problem? Maybe. Maybe not. But it is one reason why such noise could happen AND a very common and overlooked failure in homes.
You have described noise. Noise might be single volt transients on a utility wire. Surge protectors ignore most below its let-through voltage: typically 330+ volts. Are those popping sounds from 330 volts? Most likely not, since otherwise you now have damaged appliances, GFCI receptacles in bathroom and kitchen, failed smoke detectors, etc.
IOW start by inspecting the most obvious. All utilities must connect to same earth ground where all utilities enter the building.
Popping sounds may be voltages of single or a few ten volts. But they would also be composed of frequencies well above 60 Hz. The multimeter is not good for observing those higher frequencies. The common tool to see such 'pops' would be the oscilloscope. Now a very common tool these days.
And so we should try to relate the popping to other event such as the powering off of a refrigerator or other heavy appliance. Or something occurring in the very few neighbors who share your same AC utility transformer.
Noise from speakers is common because those computer speakers generally use inferior power supplies - not very well filtered. You could build a box containing the filter that should have been inside the speaker power supply using industry standard line filters such as: http://www.schurterinc.com/products/usa/pemfilter.asp http://www.corcom.com /
Appreciate the can of worms you have decided to open. EMC is quite difficult to solve sometimes. First you should locate the source of that noise. Then the best place to solve that noise is at or inside the offending device. The line filter is not just to solve the problem but to provide more data (and a tool) that might identify the noise source.
Meanwhile, the house utilities must be earthed per post 1990 National Electrical Code requirements. Even if that does not solve the noise problem, it does address or avoid other potentially future problems. Just one more suspect to verify. A problem so obvious when it is located and solved. But one that may take days or weeks of observations before suddenly the "Ah-ha" breakthrough occurs. Welcome to the world of EMC/RFI.
Bill Davis Jr wrote:

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Bill Davis Jr wrote:

What conditions produce this sound? There are two possibilities I see.
If the sounds appear to occur randomly then its probably static electricity generated by yourself. You need to be grounded, or you need a grounded floor mat if there is such a thing.
Personally I have one of those plastic mats, and whenever I cross my legs or roll my chair, I get popping in my speakers.
--
Respectfully,


CL Gilbert
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I've heard worn switches can arc slightly and send out massive RF waves.
check if anyone is operating a switch when you hear the pop.
later,
tom @ www.CarFleaMarket.com
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