>on 4/29/02 4:32 PM, Robert Eye at [EMAIL PROTECTED] wrote: > >> I want to replace the fan in my Rev A iMac with a quieter one. >> >> Anyone know what size the iMac fan is? >> >> What about a source for a quieter fan? >> >> (The Silencer� Cooling Fan from PC Power and Cooling looks like a good >>option, >> if the iMac fan is an 80 or 92 mm fan.) >> > >My suggestion is, DON'T DO IT. I tried it, it didn't work well. The >problem is the cooling fan sits right below the CRT gun. The spinning >magnetic field from the fan causes a nauseating wobbling effect on the >screen. If you insist on replacing it, it is a standard size 92mm fan but >be sure you get a brushless fan. The spinning magnetic field is much weaker >on a brushless motor than a standard one. > >A better way to quiet your iMac is to slow down the fan. I did that several >months ago and it still runs fine. Now the hard drive is the loudest >component in my mac, and heat has not been a problem (the computer is on >nearly 24/7). > >Here's a message I posted 2/13/02 with my experience: > ><begin message> >Just to update everyone with a Rev A-D (tray loading) iMac. I've been >working on quieting down that jet engine of a cooling fan. > >First I tried a replacement fan. That was a bad idea. I should have >predicted what would happen. The fan sits right below the CRT gun. The >spinning magnet in the replacement fan created an interesting wobbling >effect in the screen that quickly made me sick. I guess that's why the >original fan is brushless, so back went the original fan. > >Next I decided that if I couldn't use a replacement fan (brushless fans >aren't easy to find) then I could at least slow down the original fan. >After some quick number crunching I knew I'd need somewhere between 30 and >100 ohms resistance to slow things down so I bought some 1/4 watt, 33 ohm >resistors. With one resistor things were still more noisy than I wanted and >that 1/4 watt resistor was also hotter than I thought prudent. With 2 >resistors in series (66 ohms resistance) I got a nice quiet fan but maybe a >little less air flow than I would like. Because the resistance is now >spread among 2 resistors the heat each resistor produces now seems >acceptable. I don't want to open the computer up again so I'm going to >leave things as they are for a while (it's been 3 days now) and see how >things run. So far everything's been fine. > >My suggestion, if anyone else wants to try this, is to use one 50 ohm 1/2 >watt resistor. Give or take a couple of ohms resistance. The noise >difference is truly amazing. Installation is simple. The resistor and >telephone butt connectors are available at radio shack for about 3 dollars. >You simply open up the machine as though you were installing a RAM chip. >Once open there are 2 screws that hold the fan in place. You remove those >screws and cut either the red or black wire (your choice) and crimp in the >resistor with the telephone butt connectors (be sure to trim the resistor >leads so that there is no exposed wire). Put it back together and enjoy a >much quieter iMac. > >I don't believe the slower fan will significantly affect the temperature of >the processor. The fan sits right on top of the processor and sucks air >over the processor and blows it up into the CRT cavity. The air coming out >the top of my Mac is a little warmer than before, but not much. I believe >that most of this heat is generated from the CRT as it's quite cool when the >CRT is asleep, even with processes running (like the distributed.net >client).
ebmPapst fans are brushless and so quiet you hardly know they are running. I installed one in a Color Classic. It's so quiet it's hard to tell if it's on or not. The one I used is the model 8412L. Check out their website. munker -- The iMac List is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | - Epson Stylus Color 580 Printers - new at $69 | & CDRWs on Sale! | SPECIAL LIST PRICES - Apple iMac CDROMs from $79.99, iMac DVD CDROMs from $99.99 3 port USB Hub $14.99, 40GB Hard Drive Upgrades $119 <mailto:[EMAIL PROTECTED]> Support Low End Mac <http://lowendmac.com/lists/support.html> iMac List info: <http://lowendmac.com/imac/list.shtml> Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/imac-list%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
