9 replies to this topic

[banjosforpeace]

Yes, a squealing noise. Now don't start with any disgusting thoughts about how I'm making my computer squeal!

I replaced my power supply (ATX mid-tower) about a year ago. When I first installed the new power supply it made a high-pitched noise when it ran but went away after a few days. Two days ago I heard it again. I turned the computer off for a few hours and started it up again. After about 15 minutes it gradually began to make the noise louder and louder. I turn it off to cool everything down and try again. Between 15-20 minutes it comes back. This obviously makes me think it has something to do with the power supply overheating, but I'm not completely sure. Has anyone else heard of this? What can I check?

Also, I have another thread (Advice on Eliminating audio noise) running about a different noise. It is sort of an intereference noise that I'm hearing through the speakers. I mention this because while I'm hearing the power supply squeal from the back of the computer, I also hear it through the speakers. I want to make clear that these are two different noises, with one thing in common - I can hear both through the speakers.

Thanks to anyone who can help!

[qwijibow]

I think its probably the fan bearings.
if the bearings are slack the flades can start spinning off-center, and get held off center by the centripetal forces. which may be why powering off fixes it.

if you are comfortable handling such a device, replaceing the fan is easy,,
but be warned... inside a pc power supply are some very very large capacitors hooked up to main voltage, it one retains chage and you short it, it will hurt alot !

more expensive but safe option, replace the psu.

[Ploforia]

Definitely sounds like the power supply. The bleed into the speakers is probably an electronic annomally. I agree the reason it seems intermittent is because the centrifugal force of the fan once it gets off alignment holds it there. Best bet: replace the power supply it's like $25 (us) for a used one $50 for a new one. If you have little or no elctronics experience, you will make up what you save in pain or life if you recieve a shock - there is enough amperage in there to stop your heart.

Be careful

[Dyth]

Next thing you know, it'll be an orchestra.

[banjosforpeace]

Next thing you know, it'll be an orchestra.

<{POST_SNAPBACK}>

That's funny!

So I opened up the power supply... lo and behold, the fan is missing a blade! It must have broken off somehow! So the fan is wobbly because it is missing a blade and causing the exact noise described above. This is great news becuase it should not be an expensive fix. However, it really irks me that a power supply that is less than a year old would throw a blade and cause me such problems.

Thanks to everyone for the replies! At least I don't have to replace the whole thing, only the fan. Once again, my fellow forum users assist with sage advice!

[Xevian]

Whoa... Are you sure your house is not haunted??? I would have freaked out by now from all that wierd noise!

[banjosforpeace]

Whoa... Are you sure your house is not haunted??? I would have freaked out by now from all that wierd noise!

<{POST_SNAPBACK}>

No, not haunted. Just really a crappy electrical system and poor grounding. It gets weirder, though. Sometimes when my upstairs neighbor turns on her bedroom lightswitch I get FM radio through my right speaker! Weirder still, sometimes it is an oldies station and sometimes it is alternative rock! Sometimes The Monkees, sometimes The White Stripes! I can walk over to the stereo and tune in the same station! haha

Anyway, that's unrelated to my other noises. I'll be replacing the fan in the power supply myself and it should be pretty simple. The connector is a two pin plug, unlike my last one that had the fan wires soldered to the board.

qwijibow mentioned something about the danger of working inside the power supply because of the large capacitors that keep their charge. There are two tricks I learned working on my old Fender tube amplifier. I wonder if they could apply here. WARNING * DO NOT TRY THIS UNLESS YOU ARE KNOWLEDGABLE * I'm only speaking of amps here.

On a tube amp, you can turn it on and strum the guitar while pulling the plug out of the wall. You can hear the sound fade as you strum. This can reduce the amount of charge in the very large caps. There's also a method by which the amp is off and unplugged, where you take very well handled screwdriver - CAREFUL NOT TO TOUCH ANY METAL ON THE SCREWDRIVER - and hold the metal against the amp chassis while touching the metal top of the cap. Any really good electrical techies know if this would work?

I'm not recommending ANYONE DO THIS... EVER!!! So... DON'T!

[tansqrx]

First I don’t know if I would even bother discharging the capacitors unless I had to work on the circuit board itself. Most of the dangerous connections are under the printed circuit board and you would have to unscrew the board just to get to them. Just clip the fan wires and then put a new fan in without worrying about the capacitors.

For anyone who is concerned about discharging a capacitor, a screwdriver across the leads will do it but is not recommended because of the very high instantaneous energy transfer. Basically the screwdriver blade will have a very low resistance (perhaps .5 to 2 ohms) which will cause sparks to fly on a fully charged capacitor. The better way would be to use a 1000 to 2000 ohm resistor or even a 100 watt light bulb to draw the energy off more slowly. http://ezinearticles...o...es&id=64778 or http://www.howtodoth...rge-a-capacitor

As for the weird radio signals on your speakers, it sounds like your building has some serious grounding problems. Since you have an upstairs neighbor I suspect you are renting and I don’t know how much you can do about the problem. On the other hand, if you are mad at your landlord, you can insist on having a licensed electrician examine the wiring in your apartment. Both local and national codes require proper grounding (in the US) so grounding can lead to very specific actions that your landlord will have to take or else get fined by the city.

Another possibility on your speakers is missing shielding. Either the shielding in the speaker enclosure or in the wires could be damaged. That 10 foot of wire running from the computer to the speakers can act as an excellent FM antenna if it is damaged. Sometimes you can also put a RF choke on the wires to eliminate interference. You will notice that your monitor cable has a cylindrical device on it next to the connectors. This is a classic RF choke that helps keep interference from being displayed on your monitor. You can get one from Radio Shack (http://www.radioshac...oductId=2103222) or any other electronics store if you prefer not to go with “Ripoff Shack”. A general explanation of a RF choke can be found at http://en.wikipedia....e_(electronics).