My computer power supply fan is terribly noisy when I first turn it on. After a few minutes it quiets down and is fine till the next time I turn on the computer. Then I go in my barn and turn on an electric heater and the fan in there is just as noisy, but it too quiets down once the thing is running for a few minutes. Why do these small fan motors do that? If a bearing was bad, I dont think they would quiet down. I just learn to live with the noise as long as the motors run.
G.T.
Hmmm, Lubrication? And heat makes things expand. Those DC fans are not terribly high quality.
Small motors typically have bushings instead of bearings. Bushings wear out sooner. The axle is jigging around inside the bushing until the structure warms up a bit -- could be the axle swelling from heat, or dirty lubricant softening up, or something else a more knowledgeable person will point out later.
I fix a lot of these for clients. Clean the gray gunk off the fan blades with a can of compressed air. That usually solves the problem. If not, replace the fan. They're less than 10 bucks, unless you go for the gaudy ones with LEDs. Clean out all the rest of the dust in
If you want, you can try some light oil, but don't use much. You definitely don't want oil inside your PC. In fact, don't use oil unless the fan blows OUT of the case. I've always just replaced the fan, because I'd have to charge more for half-measures.
I won't presume to advise you about your heater. Your barn might burn down, and then I'd be sad.
Fan designers have two principal ways of increasing output. Increase horsepower or increase r.p.m. Increasing speed is a lot cheaper than horsepower, ergo, NOISE.
Ivan Vegvary
They need oil. On the computer fan, most can be lubricated by removing the paper label right in the center. few drops of oil, and a piece of tape and it's quiet.
That's very simplistic. What about changing the fan pitch? The duct shape? Load-dependent speed?
Ivan Vegvary wrote:
Dont' know about these two but some bearings are oil-impregnated. When they get warm, oil seeps out of the metal. Obviously, that takes a little time. When the motor stops and they cool off, the oil is sucked back in. Clever, huh?
Check the internet, there is a whole specialized market producing products with quiet fans, quiet power supplies, chip coolers and other products to silently remove the heat. If your fan is too noisy, upgrades are available. Many upper grade mother boards will control the fan speed according to the temperature of the CPU chip.
Regarding the computer fan, some newer PCs can regulate the fan speed in relation to heat. On startup, they go to full speed as a test. You'll notice this more with laptop computers than desktop computers.
On the other hand, as they wear out, they'll make more noise when cold. There is no way to oil a computer fan motor - it's all molded into one non serviceable plastic chunk. You can order a replacement fan but it's probably more expensive than a new power supply - which is not very expensive, whcih is why they wear out quickly.
-rev
Yeah, but thats the CPU fan not the power supply fan.
True, but there are ultra quiet power supplies available also, with fan speeds controlled by the temperature of the power supply components. Depending on the brand of computer the OP has, the quality of power supply, and other fans, may be the cheapest available with a short working life. A few extra bucks buys better components, but they may not be available from many manufacturers.
Your computer has the finest power supply that seven dollars will buy you. That leaves about forty cents for the fan. I recomend you splurge and get a $30 replacement power supply and the howling will end.
Bullshit. They wear out and by the time howling has started, no lubrication will quiet them. Just replace the worn out thing if you really want to repair it.
The aftermarket exists for both.
I hate to tell you this, but because you did NOT advise me about the barn heater fan, the heater burst into flames and burned the whole barn down, killing all the animals and several workers. It was horrible. It's your fault for not giving me help. You will be hearing from my lawyer, who is also my wife, and she sleeps with the judge a few times every week, so you dont have a chance to win the case.
Well, OK, I'm just giving you some shit and the latest Jerry Springer episode.... :)
Seriously, I just oiled that fan motor in the heater. It dont seem like it's worn too badly, but the oil quieted it down. There was a little fire though, (almost). I dripped some oil on the heater coil and that sure smoked for a few seconds. It works quiet now.
This heater is strange in design. The motor looks like one of those old record player motors but the coil windings are thick. Probably a #12 enamelled wire. The heater coils are connected in series with that motor. Thats an odd design. I cant understand the point to that, other than if the motor burns out the coils will not heat. Otherwise it makes little sense and that is why that wire is so thick. Thats a lot of amperage to go thru that small motor.
The computer is next. If I dont post a reply in a few days, call Bill Gates and tell him I blew up my computer. I'm sure he will care. I just hope the power supply is not riveted. It already looks like it will be a bitch to remove in this small case.
Another comment. Why the hell do they sell household oil with perfume in it? I hate that smell, and the odor will probably be on my hands for days now. Do they do this for women? They surely dont impress men with that stink !!!!!
(Disclaimer: I just dated myself when I said "record player". If you do not know what a record player is, please contact your grandparents or someone elses grandparents for a worthwhile education in musical history and entertainment.). Or else go to:
Might be because a smaller number of turns of heavier wire is a bit less costly to manufacture? And, a motor wound with heavier wire has a slightly lower chance of the wire breaking from vibration at a termination.
Ampere-turns is what sets what the motor does, and you can get the same amount of them with lots of turns and lower current or fewer turns and higher current.
I confess I've never run into a small heater wired like that, but now that I think about it the setup sounds like it would provide a bit of positive feedback of the element temperature, which sounds sort of bass ackwards to me.
i.e. when the element is cold, the curent through the motor is greatest, causing the motor to run a bit on the fast side, cooling the element more, and conversely when the element was hot and the current draw was less, the motor might run a bit slower, leading to less cooling and an even higher element temperature.
Hopefully someone smarter than me will give us a good reason for that setup, beyond the possibly lower manufacturing cost.
Jeff
You can also buy adhesive backed acoustic padding to line a computer "tower" case with and a labrinth type "muffler" to screw over the fan opening.
IME (A sample of one.) spending about $35 on buying both of those items didn't do s**te to reduce the fan noise enough to satisfy SWMBO.
Buying her a new computer did.
Jeff
Buy a new one. Oil is just a temporary fix. Try
Here's everything I know (almost) about heater and computer fans and, perhaps, all you need to know:
smaller number of turns of heavier wire is a bit less
Depending on the type of motor, it could have its speed determined not by the current, but by the frequency.
Dave
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