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 Post subject: Control Apple Mac Pro 4 wire fans (not PWM though)
PostPosted: Thu Mar 25, 2010 10:58 am 
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Joined: Wed Mar 24, 2010 10:32 am
Posts: 6
Location: Heflin, AL USA
Hi guys,

I found this discussion and thought you guys might be able to help. I have a Mac Pro enclosure and it uses fans made specifically for Apple, but I think I've figured out how they work. Now I just want to get them working with the temp control from the motherboard.

Here's the situation:

These fans are 4 wire fans, but the 4th wire doesn't seem to be PWM. They work in the same way, except that the control wire seems to require analog 0-5V rather than PWM. When I connect it to the motherboard header, the fan does not turn at all. I've even tried disconnecting the 4th wire in order to set it in full speed mode (PWM specs) and it still doesn't turn. I am currently controlling the speed by connecting the 5V power line from the PSU to the control wire of the fan and using a voltage divider circuit with pot to reduce the speed. The fan is at full speed with 5V, but at about 1.9-2.0V it stops.

I'm wondering if there is a way to convert either the PWM signal from the motherboard to a 0-5V analog signal or reducing the 12V pin of the motherboard header to a 0-5V signal while retaining the variable output.

Thanks in advance,

BK

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 Post subject:
PostPosted: Thu Mar 25, 2010 1:45 pm 
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Joined: Thu Jan 26, 2006 1:51 am
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Location: Sweden, Stockholm
Why just not get PWM fans instead ?


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PostPosted: Thu Mar 25, 2010 2:02 pm 
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Joined: Wed Mar 24, 2010 10:32 am
Posts: 6
Location: Heflin, AL USA
I already have these and they are really nice fans. They're Delta fans that are 120x38mm and produce 130 CFM at full speed. If I were to get new decent PWM fans, it'd cost me about $60 or more. So let's see a few dollars for a simple circuit, or $60+ for new fans. I think it's an easy decision.

I mean they work now, just not controlled by the motherboard which is what I want.

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http://aquamac.proboards.com/index.cgi? ... age=1#4706


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 Post subject:
PostPosted: Thu Mar 25, 2010 8:08 pm 
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Joined: Sat Jan 13, 2007 10:16 am
Posts: 56
Location: Indiana, U.S.A.
As a starting point: Try a low pass filter and emitter follower buffer. I'm at a disadvantage, not knowing the input impedance of the control pin on your Delta fans. If the input impedance is ~10K this may be all that's required.


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PostPosted: Fri Mar 26, 2010 10:44 pm 
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Joined: Tue Feb 16, 2010 8:20 pm
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Location: Tucson, AZ
blackknighti30 wrote:
I already have these and they are really nice fans. They're Delta fans that are 120x38mm and produce 130 CFM at full speed.


I'd like to know, when you get fan control working, how the acoustics are. Apple makes REALLY quiet machines from my experience and I'm curious if I spent $40-$50 on a 120mm Mac Pro fan, if that'd be worth it over say a $10 Nexus or Slip Stream. Given they're Delta I'd assume they're ball bearings, right?


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 Post subject:
PostPosted: Fri Mar 26, 2010 10:58 pm 
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Joined: Wed Mar 24, 2010 10:32 am
Posts: 6
Location: Heflin, AL USA
Ok, I did some experimenting today. The pinout for the fans looking at it from the end of the connector looks like this:

|______|
| 1 2 3 4 |

where the top spikes are the key tabs on the connector. Pin 1 is ground, pin 2 is 12V power, pin 3 is the Tach sens., and pin 4 is the control pin. I supplied 12V to pin 2 and slowly increased the voltage to pin 4 up to 12V without frying the fan at all. This means that if you make a connector that is exactly the same as a 3 pin fan (a normal 3 pin to 4 pin molex adapter) and connect it to the PSU molex connector (these fans draw a lot of current so don't power it from the motherboard) and run two more wires to the tach and voltage wire from the motherboard to the tach and control pins of the fan, you would have control.

That being said, these fans run really fast at a full 12V and even down to 5-6V and are very loud. That's where the ULNA adapter comes in. These are simply just a 3 pin extension with a resistor inline on the power wire. There are two adapters that came with the fan and one is 150 ohm, the other is 50 ohm. These will reduce the 12V output of the motherboard header to about 5-6V or 3-4V depending on the adapter. This is a much more reasonable speed.

They are very quiet up until about 1000-1100 RPM (about 2.5V on the control line) but the specs for these fans say they are 3300 RPM fans. They move 130 CFM at 44 dB, but utilize .75A each. I also hooked a multimeter up to them to measure current draw and found that they draw that current on the control line. The problem is that the motherboard just can't handle that much current. I've also measured the current on the 12V power wire (pin 2 in the above description) and found they use about .2A on that line, but reducing the voltage to pin 2 doesn't change the speed of the fan.

My conclusion seems to be that these will just have to be manually controlled. I built a LM117T-ADJ circuit with a potentiometer that varies the voltage between 2.5V and 5V which does a decent job of controlling them. I used the output of the circuit to go to the control wire. This lets the fan range from 800 RPM to 1100 RPM and at all ranges move lots of air at near silent operation. I personally wouldn't spend $40-$50 on these as they are too difficult to control, but these are basically the same fan: http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=36_403&products_id=24322 for $16. They have almost the same exact model number (last four digits are different), but when I compared them to the specs here: http://www.excesssolutions.com/cgi-bin/category.cgi?item=ES5358, they're basically the same. The difference is that the non-Apple fans are easier to control.

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http://aquamac.proboards.com/index.cgi? ... age=1#4706


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 Post subject:
PostPosted: Sat Mar 27, 2010 4:10 am 
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Joined: Tue May 05, 2009 1:15 am
Posts: 278
Location: Sydney, Australia
3500 rpm! No wonder my Mac Pro's sounded like airplanes when they crashed (when they drop to the kernel debugger, the fans go 100%).


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 Post subject: Re: Control Apple Mac Pro 4 wire fans (not PWM though)
PostPosted: Tue May 15, 2012 5:54 am 
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Joined: Tue May 15, 2012 5:49 am
Posts: 1
hey there

just wondering if you had succesfully hacked the mac pro PCI fan?
Delta AFB0912EHE, Apple 607-3018
it is weird, i couldn't get it controlled.

i had a spare one, so i cracked open one. and the cables on the silk screen labels

Vin, GND, O/P, Vm

i tried feeding in a constant voltage or a PWM, neither can provide any means of control.
your info would be appreciated. thanks.


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