Mac Case Fan Replacement Issues

InkBlot <InkBlot.DeleteThis@ink.ink.com> writes:
> I have a Beige G3 MT, with a fan that is becoming increasingly louder.
> In my process of replacing, I came across a fan, with a 3-pin female
> connector, probably geared towards the PC world. The power connection
> from the Mac power supply is a 2-pin female. Anybody have any idea how
> I can get a 3-pin female, from a replacement fan, to work with the 2-pin
> female wire from the power supply?

The 3-pin fans differ from 2-pin variant only in an additional tacho
wire, where the fan "electronics" will pull the voltage to gnd once or
twice for every rotation. There is no harm in connecting the tacho wire
to ground.

> If this seems next to impossible, are there any good sources for
> Macintosh compatible fans?

Actually every electronics dealer should have a compatible fan. There is
only a small number of "standard" fan sizes (40x40mm², 50x50mm²
.... 120x120mm²) but height, speed and throughput vary. So be sure to
look up the specs on the current fan.

> Also, while I am here, is there any way to replace the fan in the power
> supply?

If you have to ask this question, you might try to find someone who has
a little more routine with this kind of replacement (because the power
supply theoretically can contain hazardeous voltage even when the plug
is pulled). But it's normally a routine task for people who know what
parts better not to touch after the PSU is open.

Thomas Jahns
--
"Computers are good at following instructions,
but not at reading your mind."
D. E. Knuth, The TeXbook, Addison-Wesley 1984, 1986, 1996, p. 9

In article <0001HW.BECDD82D00422365F04075B0.TakeThisOut@news.readfreenews.net>,
DaveC <me.TakeThisOut@privacy.net> wrote:

> On Wed, 8 Jun 2005 16:59:16 -0700, InkBlot wrote
> (in article <InkBlot-E6E90A.18591608062005.TakeThisOut@nntp.charter.net>):
>
> > I have a Beige G3 MT, with a fan that is becoming increasingly louder.
> > In my process of replacing, I came across a fan, with a 3-pin female
> > connector, probably geared towards the PC world. The power connection
> > from the Mac power supply is a 2-pin female. Anybody have any idea how
> > I can get a 3-pin female, from a replacement fan, to work with the 2-pin
> > female wire from the power supply?
>
> What color are the wires? Red and black are the standard colors for power to
> the fan (positive and negative, respectively). If the 3rd wire is another
> color, it is the tachometer wire. Tach wire is not required. If the fan
> doesn't run with it disconnected, connect it to the same place the black wire
> is connected.

The wires are black, red, and white.

> > If this seems next to impossible, are there any good sources for
> > Macintosh compatible fans?
>
> All fans are "Mac compatible"; fans are pretty much generic. You should match
> voltage and airflow (cubic feet per minute - CFM). Both should be marked on
> the fan or located on a data sheet provided by the fan's manufacturer.

The fan I purchased was the same size, but slightly deeper. Also, it is
rated at 0.58A, compared to the 0.44A fan that came with the system. In
addition to all this, the original fan had a resister - I think the
power ran through this. Is it something I need to worry about? By the
way, how important is CFM, as I don't know the CFM specs on either fan.

> > Also, while I am here, is there any way to replace the fan in the power
> > supply?
>
> Each power supply is unique, as to replacing internal parts. Apple treats the
> supply as one unit, and doesn't encourage disassembly. It's a "learn as you
> go" procedure, when I do such things.

I tore apart a spare fan, identical to the one being replaced, but in
worse condition, in order to find out about the resistor. I don't know
if you can tell from the images that are attached, but the red wire
appears to bypass the resistor, while the black wire is attached via the
circuit board. I don't consider myself an electrician, only a more
advanced - relatively speaking - computer user. I am willing to get my
hands dirty with this.

Shown in the second image are the connections I am dealing with. The
black connector towards the right is from my original fan. The other is
from the new, 0.58A fan. I did numerous searches in hope of finding an
adapter, but didn't find anything that would work.

Please direct me from here. By the way, thanks for help up to this
point.

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In article <0001HW.BED14A900030F2FDF02845B0 RemoveThis @news.readfreenews.net>,
DaveC <me RemoveThis @privacy.net> wrote:

> On Fri, 10 Jun 2005 14:09:38 -0700, InkBlot wrote
> (in article <InkBlot-0A9137.16093710062005 RemoveThis @nntp.charter.net>):
>
> > I tore apart a spare fan, identical to the one being replaced, but in
> > worse condition, in order to find out about the resistor. I don't know
> > if you can tell from the images that are attached, but the red wire
> > appears to bypass the resistor, while the black wire is attached via the
> > circuit board. I don't consider myself an electrician, only a more
> > advanced - relatively speaking - computer user. I am willing to get my
> > hands dirty with this.
>
> If the resistor is inside the fan, you don't have anything to worry about.
> Only if the resistor was external to the fan is it something you need to deal
> with. Internal wiring is unique to each fan is not your concern.
>
> > Shown in the second image
>
> What image? Images are not allowed on text-only news groups; they're stripped
> off when you post. Can you put them on some storage at your ISP? Or Yahoo, or
> such?

I didn't realize this is a text-only news group. Even so, when I access
my post with images, the images appear. Anyway, I tried the new fan out
yesterday. It works. However, I have yet to fully boot my computer
with the new fan.

After installing the fan, I noticed it was almost a third thicker than
the original. While it still fits, it does not have the same amount of
room behind it in the baffle. Is this something that should concern me?

This message is not archived