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I rescued a box of brand new 'Nidec UltraFlo V60E12BS1A7-09A032 12VDC 2.45A' fans from being thrown away and of course I haven't got the datasheet for them. The closest matching datasheet is here: http://www.nidecamerica.com/fanpdfs/c2008_1314.pdf but I suspect mine are custom made for HP.

It has four wires:

  1. black => GND
  2. red => +12VDC
  3. yellow => I thought this is tacho open collector to GND, but I can't measure any frequency on it both with and without a 10k pull up to +12V, it is near 0V all the time. On top of that the wire is as thick as both black and red, whereas the green wire is clearly thinner.
  4. green => Seems enable (0V) / disable (12V or anywhere in between)

Does anyone know the proper specs for the yellow and green wires on these fans?

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  • \$\begingroup\$ Similar question about a fan pinout. \$\endgroup\$ – Nick Alexeev Jan 31 '13 at 21:02
  • \$\begingroup\$ @NickAlexeev I have to admit that I forgot to check the 'similar questions' before I hit [Post your question]. \$\endgroup\$ – jippie Jan 31 '13 at 21:09
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    \$\begingroup\$ BLDC = Brushless DC (I find this abbreviation uncommon) \$\endgroup\$ – JYelton Feb 1 '13 at 1:06
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EDIT: Thanks to fuggetaboudit, I did some more research, and the pinout, I'd guess, is:

Black = GND

Red = +12V

Yellow = Trip-Point Alarm (see option -04 in the document)

Green = PWM (option -06 in the document)

The document I'm referring to is here. In it, it says a suffix of -09 means:

PWM speed control circuit (option -06 or -56) terminated in a third lead wire (standard = blue) and an open-collector, non-latching, low-pass/high-fail, trip-point alarm circuit (option -04 or -54) terminated in a fourth lead wire (standard = yellow).

Given that your yellow wire acts like an open-collector output and your green wire controls the fan speed depending on an applied voltage, I'd bet this is the correct pinout.

Somewhat relevant: http://www.nidecamerica.com/apps_pwm.htm

I would be very certain that Mark is correct:

Black = GND

Red = +12V

Yellow = Tach Trip-Point Alarm (After checking the Nidec Datasheet)

Green = PWM

Every Nidec fan I've encountered has followed this color scheme, and most common 4-wire PWM fans in desktop computers also use the same color scheme. Empirical evidence, but given your measurements, I'd be willing to bet they're correct.

If you have access to a signal generator, try generating a 25kHz, square-wave, 0-5V signal to the green wire, and seeing how the duty cycle of that signal affects the fan speed.

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  • \$\begingroup\$ Interesting link. -0.5V - 6V for PWM according to the link. My fan probably didn't like the 0 and 12 V test. On the other hand I think I attached only through a 10k resistor. Leaves the yellow/tacho line. I started out being convinced it was tacho, but I just couldn't measure a signal. \$\endgroup\$ – jippie Jan 31 '13 at 21:32
  • \$\begingroup\$ 70% trip-point is correct for the yellow wire. There is no pulse, but is is a sort of error output. \$\endgroup\$ – jippie Feb 1 '13 at 16:36
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I don't know anything about that fan specifically but in general:

  • The tach line is some times open collector, that is it only pulls to ground. Based on what you've said, it sounds like this is the case with the fan you have. You need to use a pull up resistor on the output to get the expected square wave.

  • The green wire is most likely for PWM control. Feed it a PWM signal at various duty cycles to control the speed of the fan. Basically the fan has an internal transistor in the power path that you can switch using this input.

See here for some background: http://www.maximintegrated.com/app-notes/index.mvp/id/1784

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  • \$\begingroup\$ I edited my question for clarity with the remark that I used a 10k pull up to +12V when trying to figure out the yellow wire. \$\endgroup\$ – jippie Jan 31 '13 at 21:17
  • \$\begingroup\$ Did you try it without the pull up? \$\endgroup\$ – Mark Jan 31 '13 at 21:20
  • \$\begingroup\$ Also - what are you using to measure the voltage? O-scope? \$\endgroup\$ – Mark Jan 31 '13 at 21:21
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    \$\begingroup\$ Oh. The multimeter is your problem. The tach output is going to send one (or more) little pulses of voltage every time the fan spins around. You need to count these to get the speed. With a multimeter your only going to see the 'average' voltage, which is bound to be tiny given the low duty cycle. You need an oscilloscope to see whats going on. \$\endgroup\$ – Mark Jan 31 '13 at 21:28
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    \$\begingroup\$ I would venture a guess that the multimeter may only work on signals with a near 50% duty cycle. e.g. a clock signal. The output of a tach is going to have a very low duty cycle, the pulses are very narrow. \$\endgroup\$ – Mark Jan 31 '13 at 22:01

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