reducing 4/330 fan noise?

[Steve Simmons]

Eric.Cooper at cs.cmu.edu writes:

>Can anyone suggest ways of reducing the fan noise of a SparcStation 330?
>I'm willing to void the warranty :-)

While I've not done this on a 4/330, it has been done on other machines
and worked well.  I'll vouch personally for my 3b1.

Turn off your 4/330 and remove the fan.  Take it down to your local stereo
repair shop.  Ask for a matching size fan of the quality used in an
amplifier.  Odds are real good he'll have one.  Stereo fans are
*extremely* quiet while pulling the same (or more) cubic feet per minute
(CFM).

Caveat 1:  Without knowing the CFM rating, there is a small but real
possibility you could get an inadequate fan.  Stereo fans usually say
right on the box what their CFM rating is.  The sparcstation probably
doesn't.  You could call your salesman, who probably won't know.  You
could take the fan out, track down the manufacturer, and call them.  Or
you could do this simple test: place the old and new fans back to back,
touching.  Plug them both in.  Test to see which way the wind is blowing.
That's the stronger fan.

Caveat 2:  Many computer fans are DC, most stereo fans are AC.  The AC
fans are generally sturdier and more powerful as well as quieter.  But it
means you have to play games to convert from DC fan to AC fan.  This is
actually easier than you think.  The new fan will come with an AC cord
(but no plug) attached.  You could simply stick a plug on the end of the
fan and plug it into the wall.  This is easy, and slightly reduces the
draw on the power supply.  It has the risk that you might plug in the
computer and forget the fan.  Meltdown!  I wired my fan directly to the
input to the power supply (not to the power supply itself).  On my 3b1
this was easier than it sounds.  The power input has a plug on the outside
and a set of prongs on the inside.  The power supply clips to the prongs,
leaving about 1/4 inch of exposed prong.  I soldered the AC cord to that.
If the 4/330 has a similar arrangement you could do the same.

Credit where credit is due: Much of this information is due to the
activities of the unix-pc.* newsgroups, whose members have been replacing
fans for years.