My housemate's desktop has a noisy power supply

[vortalexfan]

Greetings everyone, I had recently mentioned something in a thread in the antique radio section about noisy computer power supplies and how they make it nearly impossible to listen to AM radio in my house, well I fixed my desktop computer's noisy power supply issue, but still have an issue with my housemate's computer power supply.

I was curious but is it normal for a desktop computer power supply to be so noisy that it backfeeds that noise all the way out to the power lines? If not then is that a sign of a failing power supply or is that possibly an illegal power supply because its in violation of FCC part 15 rules regarding radiated RF Signals? If so should I tell my housemate he needs to get a new power supply for his computer because he's in violation of FCC Rules?

Any help in this matter would be appreciated because my housemate when he's not working spends 8-10 hours straight in front of his computer screen either gaming or watching anime or youtube videos/AMVs, and when his computer is on, I can't use any of my old AM radios to listen to some Oldies or talk radio shows on which is really annoying.

Thanks for your help in this matter.

[Electronic M]

Things like many of the non-incandescent energy efficient lighting are noise generators and the FCC ignores it.

It's possible it's a sign of failure but it could just as easily be a bad design.

If it bothers you that much the easiest way to deal with it, probably, is to explain/demonstrate the issue and offer to buy him a new power supply of your choosing that is equivalent or better than the one he has.

[MadMan]

Well if you ever read those FCC stickers, all they ever say is that 'this device does not cause harmful interference.' Doesn't say no interference.

TBH, I couldn't tell you. Are you sure the noise in on the power lines and not just in the air?

Wouldn't an across-the-line capacitor in the vicinity of the radio fix power line noise?

[MIPS]

My mom's laptop AC adapter was horrible at murdering FM reception until a noise filtering power strip and two chokes were added the the AC cord.
I find a lot of the cheaper power supplies omit AC line filtering components to cut costs. I got a small pile of junk reference design 300-500W ATX power supplies from the 2000's that are all like that.

[ppppenguin]

If it's any consolation, it's just as bad in UK and Europe. The CE mark is compulsory on all electronic equipment and much else. It is meant to mean that the equipment is compliant with all applicable standards for safety, EMC etc. Rather like the FCC and UL marks in the USA. In practice the CE mark is widely abused and perjoratively referred to as meaning "China Export".

[jr_tech]

Given the house wiring problems described in another thread, I must ask if the computer is properly grounded?

jr

[dieseljeep]

Originally Posted by jr_tech

Given the house wiring problems described in another thread, I must ask if the computer is properly grounded?

jr

The original poster stated that there was a lot of bogus wiring practices. Chances are the power strip, if used, is plugged into a receptacle that was not effectively grounded.

[user181]

While grounding is certainly important, it will have no bearing on a noisy switched-mode power supply (SMPS).

[dieseljeep]

Originally Posted by user181

While grounding is certainly important, it will have no bearing on a noisy switched-mode power supply (SMPS).

There's been a trend for many years to provide an isolated ground for computers and similar equipment. It's not dependent on the raceway or the BX cable armor. It requires a separate ground conductor going back to the service panel ground bus. The bright orange receptacles you see in some locations are isolated ground receptacles.

[user181]

Originally Posted by dieseljeep

There's been a trend for many years to provide an isolated ground for computers and similar equipment. It's not dependent on the raceway or the BX cable armor. It requires a separate ground conductor going back to the service panel ground bus. The bright orange receptacles you see in some locations are isolated ground receptacles.

That's mostly in commercial facilities, data centers, and hospitals. There are a few reasons for doing this, but my point was that regardless of grounding, SMPS are very noisy, electrically. Noise gets conducted back through the power mains, and it also gets radiated.

[vortalexfan]

Originally Posted by MadMan

Well if you ever read those FCC stickers, all they ever say is that 'this device does not cause harmful interference.' Doesn't say no interference.

TBH, I couldn't tell you. Are you sure the noise in on the power lines and not just in the air?

Wouldn't an across-the-line capacitor in the vicinity of the radio fix power line noise?

I'm sure its not in the air, its on the line, because I can use a little Sony transistor radio from the 1970s and hold it up against the wall where there is a known run of wire and it will buzz like mad, but if I point the radio away from an area where the wiring is at the buzzing stops and the radio functions normally.

Also there was a day that my housemate was home and using his computer and I came back from running some errands and as soon as I pulled up to my parking spot where I live (I park outside along the road underneath some power lines) the radio started buzzing like mad and it was coming in just fine before hand, which is a confirmation that the noise my housemate's computer power supply is making is definitely on the powerline.

[init4fun]

Here's the perfect solution.....

One day, when no one's lookin, ya sneak up quietly on his computer with a big ol war club, take a quick look around to make sure no one's watchin, and then BAM!, ya club that sucker like a seal.
When the housemate freaks, ya quietly explain to him that the computer was secretly emitting mind control waves, and had to be eliminated to preserve all of humanity.

And then hopefully, your new housemate's computer has a nice quiet power supply

Your Welcome

[Electronic M]

Originally Posted by init4fun

Here's the perfect solution.....

One day, when no one's lookin, ya sneak up quietly on his computer with a big ol war club, take a quick look around to make sure no one's watchin, and then BAM!, ya club that sucker like a seal.
When the housemate freaks, ya quietly explain to him that the computer was secretly emitting mind control waves, and had to be eliminated to preserve all of humanity.

And then hopefully, your new housemate's computer has a nice quiet power supply

Your Welcome

[Kevin Kuehn]

We need to remember anything being called a ground is not necessarily ground at radio frequencies. When listening to AM indoors with no outside antenna connected, a large portion of the signal is really being re-radiated from the wiring inside your home. Long runs of supposedly grounded wire can make a very good indoor antenna. If you don't believe me try connecting the antenna terminal of your favorite AM set to different ground sources and see how the signal varies.

[vortalexfan]

A little update on this issue, I think the issue with my housemate's computer power supply is getting worse because I was driving back from my parents house today and when I pulled into my neighborhood (which has overhead powerlines) and when I got around the first 90 degree turn in my neighborhood (its a horse shoe shaped neighborhood with no outlet at the end that I live on) I suddenly started hearing the same kind of interference that I would hear when my housemate has his computer on on my car radio, and I was really far away from my house (like a block and a half away) and also its to the point that no amount of trying to reorient the battery powered radios I have to try and cancel out the interference is working anymore.

And yes unfortunately none of the wiring in my house is grounded (they have grounded outlets but they don't have ground wires running to them at least according to my surge protectors which show the ground light being unlit which means they are not grounded) they have a "ground wire" running to the electrical panel (which is actually just them running a "ground wire" to one of the old lightning rod "ground stakes" next to the house, but other than that there really isn't any ground wires going to any of the outlets in the house.)