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Computer fan with 4 wires, 5 pin connector

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I sit here with a 92mm computer fan that I pulled out of a scrapped HP server. The computer model name is "AFB0912DH", and is rated 12V / 2,5A.

The wire colors is: Black, Red, Yellow and Green. The connector have 5 pins and the two first is shorted (both black).

I will guess that black/red is power and the yellow and green is pmw/speed. The problem is that I cannot find any documentation on this, and I won't destroy the fan by pushing PMW input on speed output (because a search on ebay indicates that this fan is more expensive than regular computer fans).

So it would be very helpful if anybody have a clue about the pin-numbers for a 5-pin can connector.

Have done some web searches for "computer fan 5 wires", but I cannot find any that covers this type of connector.

I found a site that have a picture of a matching fan:
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I have some fans here and they are Black, Red, Yellow and Blue. The yellow is sense and the Blue is PWM. Try powering it and look for a signal on one of the other wires, even a multi-meter on DCV will give a reading on the sense output, on Hz you should get RPM.



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Since the first two pins are shorted, this could maybe help you.

From a test I did on what seemed a "standard" 4-pins connector PC fan, having the black wire on your left, I got:

black - GND
yellow - +12V
green - tacho signal - 2 pulses per revolution (output)
light blue - PWM ctrl (input - see below)

The 3-pin fans may be used here knowing that you do not have the PWM control available.

As per the governing standard (reccomendations?) the PWM control should be a nominal 25KHz signal (0 to 5V). Look for that standard to know about the "iddle" speed.

Worth to note:

Those PC fans get their voltage unaltered; control is via PWM.

At the tacho output I used a 10K pull-up resistor to 12V.

With no signal in pin 4, the fans goes faster.

0V on pin 4 gets the fan running to a supposed "minimum" of 30%. (Read the standard).

Steady 5V on pin 4 means NO change in speed.

PWM ctrl (between 20 and 80% that my function generator allows) seemed to have a very linear response.

Whatever you get, please post the outcome.


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Thanks, hopefully I get time to test this. I must rig up a test bench, and I have several similar projects in plan.


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My test took few minutes to connect things in a protoboard and maybe an hour to verify all stated in my post. I used a scope plus a signal generator.
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