I finally got tired of listening to the noisy fan in my duo dock, so I put a 100 ohm half watt resistor in series with the red wire that feeds 12 volts to the fan motor. It reduced the air flow as you might expect, and reduced the current draw by about 50 percent (from 85ma to 40ma, resistor and fan combined), and it reduced the fan noise a lot.
I didn't do any measurements before this mod, but I have been running a duo 280c in the dock for several hours and it is maintaining a steady 105 degrees F. as measured with a control strip module. It normally runs that warm or a little warmer when it is not in the dock. I measured the temperature of the air being blown out of the dock and it is at 88 degrees F. The above was using my 40 MHz 280c which runs slightly warmer than it did before the 40 MHz osc. was installed. It really is a lot quieter, (also didn't measure the noise level before and after) and in fact is not annoying to have it running like it used to be. It reminds me of my IIsi I used to own. I will let this list know if it ever gets too hot and causes a problem, but I don't have any concerns that there will be a problem. I think the original fan speed (air flow) was way overkill. Yes, I know that duo docks have a power supply "bad reputation", but I don't think it is due to heat that the caps fail, but rather due to under rated components, as it is simply not very hot in the immediate vicinity of the cap which typically fails (C20 ?). I should also mention that I also trimmed the corners off the fan blades on the leading edge, but I don't think that made much if any difference in the noise. Greg ---------- Duo/2400 List, The friendliest place on the Net! A listserv for users and fans of Mac subportables. FAQ at <http://www.themacintoshguy.com/lists/DuoListFAQ.shtml> Be sure to visit Mac2400! <http://www.sineware.com/mac2400> To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> Need help from a real person? Try. <[EMAIL PROTECTED]> ---------- Dr. Bott | 10/100 Ethernet for your 2400 is finally here! MPC-100 | <http://www.drbott.com/prod/mpc100.html> RoadTools $30 PodiumPad available at Apple retail stores, $20 Traveler CoolPad at Staples. Both in white for iBooks at <http://roadtools.com> Midwest Mac Parts ][ <http://www.midwestmac.com> After-market parts for Macs. ][ 888-356-1104 ][ MacResQ Specials: LaCie SCSI CDR From $99! PowerBook 3400/200 Only $879! Norton AntiVirus 6 Only $19! We Stock PARTS! <http://www.macresq.com>
