If you mount a die cast box on the side of the computer and run the power cord through it, with a good EMI filter inside, you should see significant improvement, assuming that the noise is getting out through that path.
A good filter might be something like:
Pick one with a generous current rating (say, double the expected RMS current to the supply), to keep the inductors from saturating on the peak current pulses through the line rectifiers.
Sounds like you did not spend $65 retail for that supply. To discount inferior supplies, important functions get forgotten. Sounds like the AC line filter that must be in every minimally acceptable supply was forgotten to cut costs. You would be buying expensive line filters because the line filter did not come in that supply - as is required to meet FCC regulations.
What other critical functi> I replaced a PSU in my PC, and the result is that the new PSU is more
I replaced a PSU in my PC, and the result is that the new PSU is more reliable; however, the RFI seems to have dramatically increased. The PC is in a building about 100' from the house and 75' from the garage. If I turn my car AM radio on in the garage, the interference is quite noticeable. Same with aa AM radio in the bedroom. Since the PC is already in a metal chassis, what can I do to reduce the interference? Of course, turning off the PC helps a good deal, but the PC needs to be in operation 7/24.
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15\' 7" N, 121° 2\' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small
our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
A couple of things come to mind that might help: Check to make sure the ground at the receptacle is good. Also, wrap the power cord through a ferrite choke, as many turns as you can fit. An old TV yoke might be a source for a large enough ferrite core.
Ed
Are you thinking of the AC receptacle for the PC?
Note that one of the radios could be considered a portable. The one in the car. The noise in the house radio is still there when I unplug the radio and let it operate from batteries. It seems odd that the PC would radiate through the metal chassis. Of course, it might cause radiation through the circuit from the outside building into the house. They are all connected.
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15\' 7" N, 121° 2\' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small
our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
Ah, I see now the respondent above you was driving at the PC and not the the locations where the radios are, since you clarified where to put the filter.
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15\' 7" N, 121° 2\' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small
our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
Well, almost. It cost me $49. It's a CE 350 watt PSU, CODEGEN version 3.02. The previous PSU was a CODEGEN 350 watt.
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15\' 7" N, 121° 2\' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small
our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
Does it say if it got PFC? (Power Factor Correction)
Make sure there is a line filter. Like those with two inductors in serial to the mains.
Check the front of the PC box for RFI leaks. It's usually plastic fantasic all the way.. And above all make sure grounding is appropiate. Use a multimeter to verify it's working as it should. Should all other approches fail. Build/buy a sufficient steelbox. A cheap approach is a wellpap box with tinfoil on the inside.
I'm checking on the pfc. The version # above is incorrect. It's 2.03.
-- Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
get an RFI line filter for the AC cord. when grounding the case, try to use shielded ground, that is a piece of coax using the center as the actual earth ground and connecting the shield to the ground also at the ground end only, but not at the computer end..simply pull it back a bit so that it does not touch and tape it up. get some Toriodal cores and wrap the cords through them also. all of this helps top keep the RF using the cords as antennas.
-- Real Programmers Do things like this. http://webpages.charter.net/jamie_5
As a rule PC motherboards radiate most at much higher frequencies than AM radio, and since the change made was the power supply it's most likely coming from that.
the wiring could be acting as an antenna or a transission line... do all you can to keep that interferance inside the PC'S box.
Bye. Jasen
If RFI noise is that strong, then grounding is irrelevant. Follow ground wire from computer, through walls, to breaker box. That long wire an antenna for RFI. So what has grounding accomplished? Nothing. Your problem exists at the source. From your own provided information, the power supply was defective when purchased. Price alone suggests that.
However, did power supply vendor provide a long list of numerical specs - in writing - including things such as: Specification compliance: ATX 2.03 & ATX12V v1.1 Short circuit protection on all outputs Over voltage protection Over power protection PFC harmonics compliance: EN61000-3-2 + A1 + A2 EMI/RFI compliance: CE, CISPR22 & FCC part 15 class B Safety compliance: VDE, TUV, D, N, S, Fi, UL, C-UL & CB Hold up time, full load: 16ms. typical Dielectric withstand, input to frame/ground: 1800VAC, 1sec. Dielectric withstand, input to output: 1800VAC, 1sec. Ripple/noise: 1% MTBF, full load @ 25°C amb.: >100k hrs If not, then again, you all but know that power supply does not contain many 'essential' functions. Does it even claim - in writing - to meet those FCC requirements? Quote that text exactly.
To solve this, then you did everything that pbdelete suggested. You never post again until you have opened up that power supply and verified those line filter coils exist. This is not a game of selecting only what is easiest or convenient. This is a game where you do everything and then post back. He did not waste time posting those actions. You want to solve the problem. Then do everything he has recommended.
The power supply did not cost $65 full retail. Therefore it is most likely defective when designed. Again, this is not a number you can fudge as you 'feel'. That was a blunt hard number. What is the full retail price. Less than $65? Then is it likely missing essential functions. What a coincidence. Your symptoms are exactly what would happen if that line filter (as made necessary by FCC Part 15) did not exist. Common for power supplies marketed to bean counter types who are experts because they look at two numbers - dollars and watts. Such supplies are not marketed to those who deal in reality - demand those numerical specs in writing.
Well you have this supply. Does it have the l> Could this difficulty be caused by damage to the chassis? When I
Could this difficulty be caused by damage to the chassis? When I bought the chassis, the owner sold it at a low price, since it had been dropped off a table. The frame was slightly bent but easily fixed. A year later I began to suspect that the PSU had also got damaged. Until I put in a new PSU, the RFI problem was not noticeable.
Is it possible that in putting in the new unit that something didn't get grounded properly.
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15\' 7" N, 121° 2\' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small
our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
If manufacturer and vendor did not provide numeric specs up front and in writing when you bought the supply, then neither will. Appreciate why so many power supplies are selling at less retail price and at greater profit. They are marketing to MBA types who somehow are experts and therefore do not ask for numerical specs BEFORE making a purchase. As long as those functions are not in writing, then problems are all upon you.
Why then would they even want to waste time providing specs? They have your money which is the only purpose of selling power supplies missing essential functions. Should you return it, then you may only get credit towards further purchases (maybe after a restocking charge) assuming they are willing to accept returns on electronics. Either way, they still have your money. Next year they may be selling this supply under a different name.
Let's apply your technical reasoning to another homeowner. His lights worked just fine. Therefore house electricity was completely OK. Except that his house electricity was wired completely wrong. Fortunately the resulting gas meter explosion occurred when he was not home. Just because a computer appears to work fine means the new power supply is OK? Nonsense. The new supply was creating RFI from day one. Therefore it was always defective. You are using the same flawed logic of that homeowner. You assume one can 'test' for quality which even students of W E Deming generations ago understood to be false.
Why did the previous supply become erratic? We don't even know that supply was problematic. For all we know, system was fixed by breaking and remaking connections which cleans contact corrosion. Why, with numbers, was the old supply not working? Shotgun solutions only provide enough information to
*speculate* that the old supply was defective. Meanwhile RFI function (another power supply function) was not defective in that old supply - according to what you have posted. Apparently an RFI filter function is missing in the new supply- as even suggested by its retail price.
A grounding solution is bogus and an obvious waste of time if power supply even interferes with a car's radio reception. I had provided one good reason why.
No RFI leak will be that powerful. Power supply would be a perfect transmitter if missing that essential function. Shielding or grounding will not accomplish anything sufficient
- would only be time wasted. Power wires would be a perfect transmitting antenna for a 'defective by design' power supply. How will you identify AC power wires as a leak? They are suppose to 'leak' if the internal line filter does not exist - as pbdelete's inspection would reveal immediately. But again, pbdelete told you how to address the problem quickly. (I have suggested how to avoid the problem next time).
ATX power supply is already inside a metal box. Therefore supply already has shielding and grounding. Just another reason why grounding will not be a solution. If you have no intention of turning this into an electronics project, then do the filter inspection that pbdelete requested ... now. Or buy a minimally sufficient supply from a responsible vendor. Waiting for a manufacturer to respond is a fool's errand - also called trying to take the easy and convenient way out.
Power supply is a big square wave oscillator typically running at a base frequency of 20+ KHz. Any wire connected to that power supply without filters is an antenna. When power supply is off, then oscillator is not working - therefore no DC power to computer. DC power to computer comes from that 20+ KHz oscillator. A defective and powered on power supply becomes an RF transmitting station.
If power supply does not state up front that it meets FCC Part 15 requirements and European equivalents, then you can bet the farm. It will not meet specs if it was designed for bean counter customers. Was FCC requirement and other critical functions even printed on the power supply's label? If those functions exist, then they would be printed on that label.
How would I solve the problem at less cost and time? Go buy a resp> As I think I mentioned above, in another part of this thread, the
As I think I mentioned above, in another part of this thread, the vendor has not responded yet. There is no list. I'm waiting for a reply.
If you are convinced that the power supply is at fault, then I can simplify matters by taking it back. However, you have not explained why the original power supply, which is virtually the same as the one that's giving me the problem, did not have this problem. It certainly had a problem, but not this one. It functioned quite well for many months, and then became erratic. It never caused this much RFI.
Ah, I missed part of his message. I saw the part about PFC and put that to the venodor. As said above, no answer yet. I called the store where I bought it and they couldn't tell me.
If you don't mind, I'll just wait for the vendor to chime in before responding to pbdelete's:
"Check the front of the PC box for RFI leaks. It's usually plastic fantasic all the way.. And above all make sure grounding is appropiate. Use a multimeter to verify it's working as it should. Should all other approches fail. Build/buy a sufficient steelbox. A cheap approach is a wellpap box with tinfoil on the inside."
While we are waiting for that magic moment, perhaps you, or someone, can tell me: 1. how I'm going to check for RFI leaks 2. make sure grounding is appropriate, 3. verify it's working as it should? A wellpap box? Huh? Build or buy a steel box? No thanks. I either spend money for a better PSU or exchange this for one that does work. I have no intention of turning this into an electronic project. If you plan to respond to these questions, because I really do not intend to follow them. I would like to know though what a wellpap box is?
Continued below.
No comment.
This is not news.
Wait as above.
No comment.
Well, while I'm waiting to get the answers above, perhaps you can give me a clue about the following. I plugged the previous PSU into the wall with the computer turned off. No RFI. I presume that's because the PSU needs a source to actually power up, right?
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15\' 7" N, 121° 2\' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small
our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
Noise is 'routinely' blocked inside the metal (power supply) box by the line filter - if filter exists. You are fooling yourself if you think some coil on the power cord or grounding is going to solve the problem. The power supply appears to be defective when designed. It appears to be another classic example of power supplies designed for MBAs types who call themselves 'computer literate'. Overseas manufacturers have discovered a lucrative market of technically naive computer 'experts' AND have dumped product into that market for higher profits.
You don't need a local electronics store. The internet is chock full of responsible vendors who sell minimally acceptable supplies. Supplies that meet Intel ATX power supply specs - and say so. Supplies that meet FCC Part 15 and the even more stringent European standards. Supplies that must also meet ISO, CE, UL, and other standards - all in the same box. Where are those approval labels on your power supply? What other problems will those missing standard (functions) create?
A previous post listed other functions that the power supply must provide. For example, does that supply have over voltage protection (OVP)? If not, then a power supply problem could destroy every other component inside a computer - later. OVP was standard even 30+ years ago so that a power supply failure to 'never' damage other computer parts. And yet power supplies missing essential functions such as AC line filter would also 'forget' to include other important functions.
How would you know if that supply has OVP? As pbdelete noted - open the power supply to identify an AC line filter:
If no filter, then you are not going to fix that supply. Other essential functions, such as OVP, are also probably missing. A supply designed for bean counters - people who are so often the reasons for failure.
Noted earlier was how a power supply sells at lower price for greater profits. OVP is but another function routinely missing on power supplies designed for bean counter consumption. Power supply that provides no written specifications because so many such 'computer experts' only look at two numbers - dollars and watts. People who will rationalize their decision rather than take hard and conclusive actions.
If that power supply does not have an AC line filter as pbdelete asked to inspect for, then that missing function may be part of an iceberg. Your only viable solution is a new power supply from a responsible power supply vendor and manufacturer. Some computer parts houses don't even stock such supplies.
Meanwhile, what is accomplished by learning AC house wiring? Learn which wires are better and worse transmitting antennas. Again - and it should be so painfully obvious - no grounding was going to solve your RFI. That ground wire inside the wall only becomes a transmitting antenna - as was stated previously.
There is no plug-> First, let me note that I am in a community where electronic supplies
First, let me note that I am in a community where electronic supplies are not readily available--6K people in the Sierra foothills miles and miles from Sacramento. I'm 60 miles from the nearest really full scale vendor, and
45 miles from a good used electronic parts store. While you wer complaining that I wasn't following pdelete's dictum, I was trying to find a reasonable coil to put around the the AC cord per other suggestions. None were readily availble. Hence, it the intervening time I certainly felt that is worth pursuing other avenues in this thread.Second, pdelete asked if the unit had PFC, so not knowing I tried to contact the vendor. The answer is now known as "No". Only their units distributed to Europe have them I am told. Further, I talked to the vendor on the phone finally, they have no spec sheets or circuit diagrams to distribute. What one sees on the box is it.
Third, I decided to pull the new supply and put in the old one to find out if my observation was correct. Yes, the old unit did not produce any RFI. I then decided to turn on another computer in the room. It did not produce any noise in the AM radio I was using to test interference. I then plugged that computer into the outlet for the other 'noisy' computer. Voilla. Noise galore.
Finally, this prompted to look for other noise sources in the three rooms of the building and examine the ground on outlet just mentioned. Since I had no clue as to how the four circuits in the small building worked, I mapped all the outlets, switches, and lights to the circuit breaker panel. Then I began experimeinting by turning parts of the circuit on and off, etc. The best I could do using this approach (so far) is to note that the one circuit that has the most devices on it is fairly noisy. I found one device, a network hub, that was a bit noisier than anything else.
Where I plan to go from here is likely to see if I can just plain quell the noise at the questionable outlet and devices plugged into it. Beyond that, I'll live with the ruckus caused on the AM portion of the dial that distrubs me the most. In the meantime, I'm close to being off this little project, and getting onto other things of higher priority. The obvious disturbance in the AM signal attracted me enough to put this much time in on it, but not enough to keep me going for days trying to squelch it. Other things first. When they are out of the way, I'll look into this further. Summing it up I seem to have an RFI problem of unknown origin.
As far as the new PSU unit is concerned, I'm keeping it. At least, it doesn't just belly up every 3-4 days.
Since you are curious about this, I'll try to do you the favor of photographing the inside of both PSUs and posting it. That's not likely to happen today.
If noth> If manufacturer and vendor did not provide numeric specs up
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15\' 7" N, 121° 2\' 32" W, 2700 feet
"... astronomy is useful because it shows [not only] how small
our bodies are, but how large our minds are." -- Henri Poincare
Web Page:
Why not shileded power cables?, especially since it's likely not complient to disconnect earth on the mains connector. Especially if something goes wrong.
Use an AM-radio, disturbances => RFI. (simple but working) You could also wire a simple directional antenna from steel wires if you want to get more accurancy easy.
Push down a pole >2meter into the ground measure between jack and pole. Also check between jack and incoming terminal. Btw, this depend on the specific electrical code in your country. So be careful.
Maybe the english word is cardboard/pasteboard. Thick paper used in packageing at least. Combined with household aluminium foil you can create a quick and cheap faradays cage to block RFI.
However as suggested in later posts. IF the powersupply "sends" it's RFI back out through the powercord. Then no shielded box etc.. will help. Unless you add an line filter. I think many are two coils in parallel combined with suitable capacitors to shortcircuit highfrequencys.
I had a look into this when investigating powercontrol via igbt and mosfet. Where one technique is modulated pwm to produce sinus. Which is nice.. except for the RFI ;)
If you have a oscilloscope then you can verify many of these things yourself. At least PFC and Line filtering should be visable. Btw, does the disturbances affect FM-band too ?
IT all depends on what mode the RFI takes,
If it;s balanced on the live and neutral conductors the only thing that'll stop it is a proper EMI filter that filteres each conductor separately.
if it's common to all three conductors then the toroid etc will stop it abd the EMI filter may not (but I count this as unlikely)
all that shielding does is keep the cable from radiating, if it's plugged into an outet shared with other unshielded cables they will radiate the RFI...
-- Bye. Jasen
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