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#16
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Tip: blowing out fans
On Mon, 11 Nov 2019 14:11:12 -0800, T wrote:
Hi All, Tip: If your fans are noisy, blowing them out won't help things. It is time to replace them. I agree. Ball bearing fans are usually a lot noisier than sleeve bearings. If your fan is clogged, DO NOT USE a shop air gun to blow it out! Use a can of compressed air that states it is for electronic equipment and capture the fan blades so they do not rotate when you hit them with air. Shop air guns have oils and other stuff yo do not want all over your circuit boards and their air flows can cause static electricity build ups. Many air compressors do not use oil lubricated pistons, so oil in the air depends on the compressor. Old garage type shop compressors did use oil. Diaphragm compressors don't, or Teflon ring piston compressors don't use oil. Water in air systems is common enough it humid conditions and that could cause some problems. Air or propane or refrigerant type cans are just as capable of causing static, but that is seldom a problem. Fans, when ran backwards with external air, become generators and send current back down their wires, which can damage your motherboards. And certainly damage any PWM circuitry on the fan. So do not let the blades spin when blowing them out. Yes, it is fun to watch them whirl -- don't do it anyway. Have you actually measured the voltage? I just did with a few fans I have and they don't produce voltage - at least they don't at the fan leads. That may be because they use brushless motors and the electronics in the fan doesn't pass the AC the magnets and coils produce to the outside world. Brush type fans are very rare and have been for a couple of decades. -T |
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#17
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Tip: blowing out fans
On 11/11/19 6:18 PM, Rene Lamontagne wrote:
NO,Â*NO,Â*NO,Â*NeverÂ*everÂ*playÂ*withÂ*aÂ*blowÂ*g un!!!!!!!!!! Blowing air from a nozzle can penetrate the skin and cause an air embolism bubble in your veins which will go to your heart and kill you as surely as a gun, I have known it to happen to a mechanic here in WinnipegÂ*someÂ*yearsÂ*back. Rene Yikes!!!! HowÂ*aboutÂ*theÂ*cat? IÂ*knowÂ*youÂ*wereÂ*jokingÂ*soÂ*noÂ*problems.Â*Jus tÂ*aÂ*reminderÂ*aboutÂ*airÂ*nozzles. I dunno about the cat never had one since 1952, I'm a dog lover, ParticularlyÂ*GoldenÂ*Retrievers. :-) Rene If you have ever experienced someone you love's lips turning blue, gasping in terror trying to breath from being exposed to the same environment as a cat, you will understand my attitude towards cats. Although, I have to admit, they make great clay pigeons. Dogs on the other hand ... Goldens are the most loving spirits. Every so often, my customer get a line item, on their bill "Play with dog. No Charge." When they get their bill, they call us up laughing. -T |
#18
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Tip: blowing out fans
On 11/11/19 7:33 PM, Jonathan N. Little wrote:
Electric leaf blower... You know, computer are very vindictive and have LONG memories. :-) |
#19
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Tip: blowing out fans
On 11/11/19 8:12 PM, default wrote:
Have you actually measured the voltage? Yes, I don't remember how high it was. Depended on how fat I spun the blades I just did with a few fans I have and they don't produce voltage - at least they don't at the fan leads. That may be because they use brushless motors and the electronics in the fan doesn't pass the AC the magnets and coils produce to the outside world. I blew out a PWD fan on for weird processor mount once. Took me forever to find a fan that would replace it. That is when I learned my lesson. |
#20
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Tip: blowing out fans
On 11/11/19 8:12 PM, default wrote:
Brush type fans are very rare and have been for a couple of decades. Good riddance! |
#21
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Tip: blowing out fans
T wrote:
On 11/11/19 8:12 PM, default wrote: Have you actually measured the voltage? Yes, I don't remember how high it was. Depended on how fat I spun the blades I just did with a few fans I have and they don't produce voltage - at least they don't at the fan leads. That may be because they use brushless motors and the electronics in the fan doesn't pass the AC the magnets and coils produce to the outside world. I blew out a PWD fan on for weird processor mount once. Took me forever to find a fan that would replace it. That is when I learned my lesson. The analysis of what happens when a BLDC fan freewheels is complicated. The coil output doesn't go to the terminals directly. http://www.pcbheaven.com/wikipages/i...1269881543.png There are actually many different schematics for those fans, as each manufacturer tries to shave nickels off the price. As a result, the behaviors of the fans may not all be uniformly the same. When the PC power drops (at shutdown), the fan is still doing 2000RPM for a couple of seconds, so the controller circuit has to withstand that much insult. And the person who designed that controller, takes that into account. If you wanted to simulate that, you could always build up a model for it in LTSpice. In your simulation, the coils are an *AC* voltage source. Because that's what comes out of them when they freewheel. Paul |
#22
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Tip: blowing out fans
On 11/12/19 3:16 AM, Paul wrote:
T wrote: On 11/11/19 8:12 PM, default wrote: Have you actually measured the voltage? Yes, I don't remember how high it was.Â* Depended on how fat I spun the blades I just did with a few fans I have and they don't produce voltage - at least they don't at the fan leads.Â* That may be because they use brushless motors and the electronics in the fan doesn't pass the AC the magnets and coils produce to the outside world. I blew out a PWD fan on for weird processor mount once. Took me forever to find a fan that would replace it. That is when I learned my lesson. The analysis of what happens when a BLDC fan freewheels is complicated. The coil output doesn't go to the terminals directly. http://www.pcbheaven.com/wikipages/i...1269881543.png There are actually many different schematics for those fans, as each manufacturer tries to shave nickels off the price. As a result, the behaviors of the fans may not all be uniformly the same. When the PC power drops (at shutdown), the fan is still doing 2000RPM for a couple of seconds, so the controller circuit has to withstand that much insult. And the person who designed that controller, takes that into account. If you wanted to simulate that, you could always build up a model for it in LTSpice. In your simulation, the coils are an *AC* voltage source. Because that's what comes out of them when they freewheel. That would definitely be part of the design. It is okay to spin the fan a little, just don't exceed by much what it is designed to spin at. Some Air Compressors can make that fan spin so faat, the computer is about to take off! And yes, it is fun. Resist the urge! I finally found 60, 92 and 120 mm PWM fans I like. |
#23
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Tip: blowing out fans
On Mon, 11 Nov 2019 16:41:01 -0600, VanguardLH wrote:
I don't remember hearing of anyone using an air compressor to dust out a computer. They sell compressed air cans for that. I've used an air compressor, several times. Everything still works. I do keep a finger on the fans to prevent them from turning otherwise the bearings may break. Outside, as Rene suggests, is also a good idea. And I use short bursts. -- s|b |
#24
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Tip: blowing out fans
On Mon, 11 Nov 2019 15:32:08 -0800, T wrote:
I had a customer spray his computer with WD 40 years ago. Oh Boy! I bet it made a lot less noise after that! -- s|b |
#25
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Tip: blowing out fans
On Mon, 11 Nov 2019 22:33:32 -0500, Jonathan N. Little wrote:
Electric leaf blower... I knew a guy who used his vacuum cleaner. -- s|b |
#26
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Tip: blowing out fans
On 11/12/19 4:19 AM, s|b wrote:
On Mon, 11 Nov 2019 15:32:08 -0800, T wrote: I had a customer spray his computer with WD 40 years ago. Oh Boy! I bet it made a lot less noise after that! If was just a small 80 mm fan spinning at full speed. What a mess he made (WD 40)! I moved the 12V plug to the 5V jack. That was before PWM fans |
#27
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Tip: blowing out fans
On 11/12/19 7:15 AM, Rene Lamontagne wrote:
Last winter we were walking down the sidewalk and we met a a Lady with a beautiful Golden, maturely I stopped to pet it and then it came and sat down beside me Looked up at me like a new friend and didn't want me toÂ*leave. I had (he died on me) a customer with three of them. One would gently pen me in so I could not leave. And yes, the big eyes are something to behold. If I had those eyes, my wife would be dead meat. |
#28
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Tip: blowing out fans
On 11/12/19 5:50 AM, Jonathan N. Little wrote:
T wrote: On 11/11/19 7:33 PM, Jonathan N. Little wrote: Electric leaf blower... You know, computer are very vindictive and have LONG memories. :-) Nope, works great just be sure to do it outside. Cheap too I think mine was a $35 Wally-Mart special. I am a married man. If I used a leaf blower inside, this group would need a new Todd. :'( |
#29
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Tip: blowing out fans
On 11/12/19 5:55 AM, Jonathan N. Little wrote:
T wrote: That would definitely be part of the design. It is okay to spin the fan a little, just don't exceed by much what it is designed to spin at.Â* Some Air Compressors can make that fan spin so faat, the computer is about to take off! And yes, it is fun.Â* Resist the urge! I finally found 60, 92 and 120 mm PWM fans I like. A simple solution when blasting to remove stubborn crud on blades is a finger on the fan BEFORE blasting away. With canned air, that can get pretty cold! I put my plastic ball point pen in them. And it is so, so much fun to see the blades whirl. Damn that self control thing! |
#30
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Tip: blowing out fans
On Tue, 12 Nov 2019 14:55:44 -0800, T wrote:
On 11/12/19 5:55 AM, Jonathan N. Little wrote: T wrote: That would definitely be part of the design. It is okay to spin the fan a little, just don't exceed by much what it is designed to spin at.* Some Air Compressors can make that fan spin so faat, the computer is about to take off! And yes, it is fun.* Resist the urge! I finally found 60, 92 and 120 mm PWM fans I like. A simple solution when blasting to remove stubborn crud on blades is a finger on the fan BEFORE blasting away. With canned air, that can get pretty cold! I put my plastic ball point pen in them. The stuff is cold because they use refrigerants. In fact there's several DIY Utoobe vids of shade tree mechanics using "Dust Off" products to recharge auto AC units because it can cost less. (and they sell a side-piercing aerosol can tap for the purpose) The danger to a computer might be from the cold - particularly if it condesnses water from the air, causes thermal stress on connections, or is powered up at temperatures it was not designed for. And it is so, so much fun to see the blades whirl. Damn that self control thing! Well, there is that. Entertainment value. |
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