Did you check the old fan with the 9V battery ?
Since you say the old fan was still working, but noisy, it
should pass the 9V test as well. Always be careful with the
polarity when using the battery method.
By reversing the wiring on the new fan (black to red), you may have
damaged it.
I don't see a particular reason a power supply would care, but fans
come in several types. If you buy a "case fan", it typically has two
wires. Red and black go to +12V and GND (assuming it is a 12V fan and
not some other voltage). At least the black color should be the
ground, leaving the other color as the more positive connection.
The next type, is the three wire fan. The third wire is for tachometer
readout. But a PSU doesn't particularly care about RPMs. I have one
power supply here, where they include a "sensor" cable, so the RPM
signal from the fan can be connected to the motherboard fan header
(I can read out the power supply RPMs as a result.) But the power
supply itself, is probably not monitoring RPMs (it costs too much
to bother).
Another kind of three wire fan, includes a different signal on the
third wire. Instead of a constantly pulsing signal, they put a
logic signal called "locked rotor". If the fan detects that it is
below a certain number of RPMs, the signal changes state. So that
flavor of fan, has a signal that is "go/no-go" for the connected
equipment. Such fans are included on "classy" equipment, such as
lab equipment perhaps. Locked rotor would normally be a non
pulsing signal, and stays in one state most of the time.
So you have some steps to carry out, as part of your repair work.
One is, to put the original fan back, and test that the power
feeding the fan is still present.
You also need to retest the replacement fans, to see if they're
damaged by the reverse polarity. The company making the fans,
doesn't usually go out of their way, to include a polarity
reversal protection diode. (I haven't tested my fans, by
reversing the polarity, so I can't tell you whether they'd
be damaged or not. There can be either a chip inside the
fan hub, or at least a couple transistors, so in fact not
all fans have exactly the same design or components inside
the hub.)
A power supply can be "bench tested", before being placed back
in the computer. For example, get a copy of the ATX standards
for power supplies. Connect "PS_ON#" to COM or ground. When
the power supply is plugged in and the switch on the back
of the supply is "ON", the missing step is to connect a
paper clip or jumper wire, from PS_ON# to COM.
Having the cover in place on the power supply, protects you
in the event that the main cap exploded. (Not that this
is likely to happen, but the cap does hold a lot of
energy. It is also charged to a lethal voltage when
operating.)
In a previous post I made on the subject, someone suggested
that it is wise to always have a slight load on the supply.
If you have a couple old hard drives you are no longer using,
you might consider connecting them to the 1x4 Molex hard
drive connectors. That would provide a very small amount of
loading, about 5V @ 1A and 12V @ 0.6A or less. A couple of
drives would double that load, to 2A and 1.2A. Some supplies
actually have a minimum loading spec, printed on the label,
and if your "dummy load" is not meeting the minimum stated
value, then you'd look for another way to meet the
minimum load.
I have a load box for testing power supplies, that I built
myself. I bought about $50+ of power resistors from the only
good electronics store in town. They also had Mini-Fit Jr.
crimp pins, so I could make a connector assembly. I included
a fan in my load box as well, to blow over the power
resistors. The box might draw about 100W or so, which is pretty
small as loads go. The load box has a switch, which connects
PS_ON# to COM.
Using a box like that, I can test a new supply, before using it
on a new build. I can connect my multimeter and verify the
voltages under that 100W load. At least I can determine whether
the supply is way off, on one of the output rails, before
connecting an expensive motherboard.
I've only ever replaced one fan on a supply, and the only reason
for doing it, was the supply was from an old Macintosh
computer. Like yours, the fan was noisy. Fortunately, the fan
had the standard three pin connector on the end, so removing
the old and inserting the new, was easy. The three pin header inside
the supply, had the standard keying scheme, but I also verified that
the wire color scheme on the old fan, the voltage etc, also matched,
before doing it.
For PC supplies, I'd just buy a new one. But for that Mac, finding
something with the right power connector pinout, would have been
a hassle. Probably nothing but pulls would have been available.
Some power supply specs can be found here. The oldest spec is for a
20 pin supply which still has -5V. The second is for 20 pin supply,
where the -5V has been removed. The third, is for a 24 pin supply,
where the extra pins provide more current flow for some of the
rails. You can find the color and location of PS_ON# in these
docs.
http://web.archive.org/web/20030424061333/http://www.formfactors.org/de
veloper/specs/atx/ATX_ATX12V_PS_1_1.pdf
http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf
http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.p
df
Working inside a power supply, should only be attempted if you know
what all the potential risks are. In my case, since the old fan
could be unplugged, I didn't need to take the supply apart, and
expose any of the high voltage areas. Otherwise, I might have just
bolted the whole thing back together, and lived with the fan noise.
Did I mention I don't really like high voltage ? Or getting shocks ?
The purpose of giving warnings, to stay out of power supplies, is
some day, we're going to read in the newspaper, where someone
was killed, because of advice given. And we definitely don't want
that. It is not like you'd be posting back, if you were killed.
Another reason the replacement fan might not have worked, is the
PSU can use variable voltage to feed the fan. When the PSU is
cool, at startup, it might deliver 7V to the fan wires. As the
internal component temperature rises, the voltage is increased, to
make the fan spin faster. It could be, that the new fan and old fan
have a difference in the minimum starting voltage. For example,
the other day, I saw a fan spec, where 10.8V was listed as
the minimum starting voltage. There are some other 12V fans,
that will start with as little as 5V present.
Fans also have different air moving capacities, measured in CFM.
Roughly speaking, fans comes in low, medium, high, and ultra
ratings. When replacing a fan, you want to try to match the
characteristics of the original fan.
