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#1
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AM radio noise
I've had this problem awhile but it seemed to be getting worse. My
computer pretty much wipes out my AM radio (FM unaffected). All the wall sockets in my room are on the same circuit so I'm out of luck moving the radio. Now... I expect the AM radio to go bonkers if the system is on but this happens when the computer is off too. If I switch the power supply to off in the back of the case all is well. Is this normal? The graphics board always has a light on (Radian 9600 pro) for the 8x agp but I wouldn't think this would have that kind of affect. I hooked the computer up to a belkin surgemaster with a high frequency capacitor to no avail. I hooked my AM radio to the same surge protector and again zippo. Could the power supply be the culprit? If so are there ones on the market anyone could recommend that wouldn't contaminate the AC line of the house? Thanks Randy |
#3
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Common problem when that computer expert selected a power
supply based upon price rather than on technical specs. Power supplies must have an in-line filter. But many important functions are forgotten to sell power supplies at less than $80. Missing functions when a power supply is not provided with a long list of specifications including: PFC harmonics compliance: EN61000-3-2 + A1 + A2 EMI/RFI compliance: CE, CISPR22 & FCC part 15 class B Where does that surge protector even cite numbers for noise reduction? It remains inert - does nothing - until voltages above 300 volts are observed. But then even that number is often in small print. Again, if no specifications, then why would you assume something will work only based upon an arbitrary comment (such as high frequency capacitor). Once numbers are provided, then surge protector does not even claim to address your problem. First confirm the power supply claims to provide a long list of essential functions, or replace it. Cheap power supplies can even contribute to damage of other computer components. Randy wrote: I've had this problem awhile but it seemed to be getting worse. My computer pretty much wipes out my AM radio (FM unaffected). All the wall sockets in my room are on the same circuit so I'm out of luck moving the radio. Now... I expect the AM radio to go bonkers if the system is on but this happens when the computer is off too. If I switch the power supply to off in the back of the case all is well. Is this normal? The graphics board always has a light on (Radian 9600 pro) for the 8x agp but I wouldn't think this would have that kind of affect. I hooked the computer up to a belkin surgemaster with a high frequency capacitor to no avail. I hooked my AM radio to the same surge protector and again zippo. Could the power supply be the culprit? If so are there ones on the market anyone could recommend that wouldn't contaminate the AC line of the house? |
#4
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"Randy" wrote in message
om... I've had this problem awhile but it seemed to be getting worse. My computer pretty much wipes out my AM radio (FM unaffected). All the wall sockets in my room are on the same circuit so I'm out of luck moving the radio. Now... I expect the AM radio to go bonkers if the system is on but this happens when the computer is off too. If I switch the power supply to off in the back of the case all is well. Is this normal? The graphics board always has a light on (Radian 9600 pro) for the 8x agp but I wouldn't think this would have that kind of affect. I hooked the computer up to a belkin surgemaster with a high frequency capacitor to no avail. I hooked my AM radio to the same surge protector and again zippo. Could the power supply be the culprit? If so are there ones on the market anyone could recommend that wouldn't contaminate the AC line of the house? Thanks Randy Sounds like you need a line noise filter for your AM/FM radio, like at Radio Shack (http://tinyurl.com/htqm). However, I don't think you can use it for your computer as its function is to eliminate line noise from the input side, not getting introduced from the output side. All other devices will also be affected by the noise that your computer power supply is putting on the line, so you might want to plan for a better power supply. |
#5
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Filter is not unidirectional. However a filter superior to
that Radio Shack product must be inside the power supply. Too many computer experts don't even have basic electrical knowledge. Therefore many clone computers have power supplies selected only on one specification - price. It is called the MBA mentality. Inferior power supplies can be dumped into N America at even greater profit because too many N American technicians don't even know what a power supply is suppose to do - never read specifications - don't even have basic electrical knowledge. They are called low pass filters. They work in either direction. Nothing technically advanced about that electronic knowledge. Would be nice if Radio Shack gave even one specification other than price. But then this filter, like so many computer power supplies, is also being recommended without any technical knowledge - no number or specifications need be provided. Buy a power supply for $40 that is missing many essential functions including that low pass filter. Then spend another $40 for every other appliance to filter the noise. This is why cost controller mentalities cause major cost increases. Until a minimally acceptable power supply is installed, then all other solutions are wasted money and time. Minimally acceptable starts at about $80. If noise is not quashed at the source, then every wire connecting to that computer becomes a potential transmitting antenna. Noise filter is not required. The problem first must be fixed. Solution starts with specifications. "Vanguard °°°" wrote: Sounds like you need a line noise filter for your AM/FM radio, like at Radio Shack (http://tinyurl.com/htqm). However, I don't think you can use it for your computer as its function is to eliminate line noise from the input side, not getting introduced from the output side. All other devices will also be affected by the noise that your computer power supply is putting on the line, so you might want to plan for a better power supply. |
#6
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Get a battery operated AM radio.
"Randy" wrote in message om... I've had this problem awhile but it seemed to be getting worse. My computer pretty much wipes out my AM radio (FM unaffected). All the wall sockets in my room are on the same circuit so I'm out of luck moving the radio. Now... I expect the AM radio to go bonkers if the system is on but this happens when the computer is off too. If I switch the power supply to off in the back of the case all is well. Is this normal? The graphics board always has a light on (Radian 9600 pro) for the 8x agp but I wouldn't think this would have that kind of affect. I hooked the computer up to a belkin surgemaster with a high frequency capacitor to no avail. I hooked my AM radio to the same surge protector and again zippo. Could the power supply be the culprit? If so are there ones on the market anyone could recommend that wouldn't contaminate the AC line of the house? Thanks Randy |
#7
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That won't work. I try to run a battery one near the computer and getting
within 5 ft generates interference. It is frequency dependent so it is much stronger in the lower AM band. Use Internet radio to listen I guess. "jaster" wrote in message m... Get a battery operated AM radio. |
#8
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rcm wrote:
That won't work. I try to run a battery one near the computer and getting within 5 ft generates interference. It is frequency dependent so it is much stronger in the lower AM band. Use Internet radio to listen I guess. There are two kinds of RF interference, conducted (usually through the power lines), and radiated, directly through the air. PC cases are supposed to shield against radiated interference, but openings in the case, poor contact between side panels, etc. can negate this. As w_tom says, the PS should have line filtering for conducted noise. (The FCC requires units sold in the US to pass tests for this.) All switching power supplies generate RF interference over a fairly wide band. Even when "off", the ATX PS has a stand-by supply that is constantly on when line power is supplied to the unit. Since a battery receiver still has problems, it is a radiated RF signal that is the culprit. You might try a better ground on the computer case than that supplied by the line cord. Check for any openings other than those required for air flow, and make sure these have metal grills. Wrapping the receiver in aluminum foil grounded to a water pipe, might be a brute force way of stopping it's reception of the PS radiated energy. You would then need an external antenna connected by a shielded co-ax, as someone has suggested.The PS generated noise is usually at about 40Khz, but it has strong harmonics well into higher bands. Virg Wall -- Be not the first by whom the new are tried, Nor yet the last to lay the old aside. |
#9
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Try to propose solutions that Randy can actually implement. Yes, he can
replace his power supply with a better unit. You're assuming he has $80, or more, to waste on a new power supply AND that he is going to install it rather than having to pay a shop to install it. Preaching the best solution regardless of financial constraints doesn't help. Others had already offered (or I expected others to offer) the high-road solution, so I proffered a lower cost solution. I didn't say it was the best solution. I just offered it as one possible solution and a different one than the expected solution. There is no point to post a "me-too" duplicate solution; a dozen replies of "get a better power supply" doesn't give Randy many options for a solution. Of course, another suggestion might be that Randy build a massive antenna with active filtering and shielding just for his little AM radio but that would be pointless without regard to Randy's financial, educational, and physical constraints. Ranting about the use of low-quality components as being a problem with lack of education in techs regarding specifications doesn't help Randy, either. It just illustrates that you are ****ed off about the situation but also that you don't seem to realize that it is the consumers that dictate the use of low-quality components in low-priced consumer-grade computers. Buy cheap, get cheap. Wow, what a revelation. MacDonalds and BurgerKing exist because there are enough consumers that want low-priced low-quality food. Same for computers or any other product where enough consumers are willing to sacrifice quality to get a cheap price. The business of business is to stay in business so you sell to whomever is willing to buy for whatever they want to buy at the price they will pay. Using cheap power supplies has nothing to do with the lack of education by techs but has everything to do with consumer economics. Randy probably cannot effect a change in the industry or influence a worldwide populace of consumers, so stop spewing farts at him about problems in the industry (which is simply matching consumer demands) or that these low-grade low-priced components don't follow specs (since it is obvious to everyone that paying the lowest price does NOT result in getting the highest quality). You are also lambasting Randy that he has a cheap power supply. Components (within components) do fail, so maybe his power supply was okay but went bad and he needs to get a new one - but another one of the exact same model might be just as good and resolve the problem without having to waste money on a solution that far exceeds his requirements. Your kid wants a wrist watch. Do you get him a $20 Timex or a mega-grand Rolex? Both are solutions but obviously one fits better within your financial constraints. I expected other posters to state the obvious solution and Randy already suspected the power supply, so I provided a different solution rather than fixating on the most costly, most time consuming, and most disruptive solution. |
#10
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"rcm" wrote in message
. ca... That won't work. I try to run a battery one near the computer and getting within 5 ft generates interference. It is frequency dependent so it is much stronger in the lower AM band. Use Internet radio to listen I guess. Since it is RF noise, I'm wondering if there is chance that it is not the power supply but some other component inside the system unit that causes the interference. Have you opened the case and unplugged the power supply from the motherboard and other devices and then powered it on to see if the noise reappears with just the power supply running? Normally an ATX-style power supply will not turn on unless it is connected to a motherboard. To test an ATX-style power supply without a motherboard connection, short the PS-On signal (pin 14) to a ground (pins 3, 5, 7, 13, 15, 16 or 17) in the 20-pin Molex connector; see http://www.hardwaresite.net/faqpowersupply.html. Then you'll know if it really is the power supply generating the noise or if some other component, like a slot card, is causing the noise. If running the power supply by itself produces no RF noise in your AM radio, reattach the 20-pin Molex connector to the motherboard (with power off, of course), leave all drives disconnected from power, and remove all cards in the slots, even the video card. Power on (the boot will fail due to the missing video card) to see if the noise is still there. If not, power down, add a card (start with the video card), and test again. If none of the cards are generating the noise, then start hooking up the drives one at a time and test. What cards do you have installed in the slots? Any tuner cards? If you have a metal case, check that the grounding clips engage at the bottom edges or wherever the cover slides onto the shell. If you don't have any grounding clips to ensure the cover gets grounded to the shell, I suppose you could try using aluminum foil folded over with enough layers to wedge between the cover and shell but this would get damaged when you next removed the cover and might not stay in place (I haven't tried this so I don't know how well this works). I'm not sure what to do if you have a plastic-only cover other than maybe spraying its inside with metal conductive paint but that wouldn't survive much wear if you frequently open your system unit. |
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