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Discussion Starter · #1 ·
I recently got a PAPST 8412 NGMLV fan with a 4 pin full size connector used on a PAL 8045 CPU heatsink on an ECS K7S5A motherboard.


There were 3 wires coming off the fan, going counterclockwise looking at the label side;

1. Red which is the +12V wire

2. Blue acts as ground

3. Purple is maybe a sensor wire, but was attached to the ground wire. It has a splice in the wire that is covered up with heat shrink tubing, but is most likely an NTC Thermistor to regulate speed.

4. Unconnected 4th solder tab on the Fan's PCB


I converted the 4 pin connector to a standard 3 pin motherboard fan connector.


Assuming the purple wire is a thermistor, It should probably be connected to ground (as indicated by their web site pdf).

The question then is does anybody have any suggestions as to where the thermistor is best located? Do I even need/want this thermistor control?


Also is that 4th PCB tab a standard fan sensor point that I can hook up to my motherboard using the standard 3 pin motherboard connector? What is the purpose of that 4th pin if not that? Anyone know?


Thanks,


Ira
 

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MICJ,


The third wire on most motherboard fan headers is actually a fan speed sensor (pulse) wire. It's used to check the fan is still turning at the rated speed and if there is a problem, alert system monitoring software or the PCs BIOS. The "third" wire on the 8412 NGMLV is NOT a pulse *sensor* wire it's a speed *control* wire. If you plug a variable speed fan into a motherboard expecting a constant speed fan with speed monitoring - it wont work properly. If you want the "correct" low speed 80 mm Papst fan type for most motherboards it is the 8412 N/2GL (1500 RPM) or 8412 N/2GML (2050 RPM - the /2 signifies pulse sensor type - see Papsts downloadable 11 Mb catalogue). I have 2 of the former in my machine and they work very quietly to get rid of the heat well - I recommend them highly for performance to noise characteristics. I know where you're coming from because I've been there and made that mistake. Once you get the new fan(s) just have a look at the motherboard pinout in the manual (or the original case fan - HSFs are the same) to see how its wired (the red and black are together and the pulse wire is at one end of the plug - mine goes black-red-yellow.


Best of luck with it.
 

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Discussion Starter · #3 ·
Thank you for the reply. Next time I will pick up the correct fan (hopefully!)


I understand how the motherboard fan connector is wired, what I was trying to ascertain was wether the 4th unconnected wire tab on the fan's PCB (just under the center part of the fan and is visible where the wires connect) was perhaps a fan pulse sensor tab that is chosen by just wiring the fan differently.


If that is the case, I'd could easily change the wire as needed. Could you check your fan (8412 N/2GL (1500 RPM) or 8412 N/2GML) and tell me how the 3 wires are hooked up to the 4 solder tabs on the fan's circuit board, assuming there are 4 tabs?


Thanks in Advance,


Ira
 

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Wow this is uncanny.... been there tried that too! My old Papst fans have all had an extra solder pad and like you (originally bought the wrong ones for my previous PC), I thought I'd try and convert a non pulse sensed fan into one that is, just by soldering the extra wire on. Bad news I'm afraid - it doesn't work, the fan will still turn but the motherboard won't recognise its speed. My current /2 fans have exactly the same pad layout but of couse the extra wire came presoldered in place. I guess there must be components missing off that little PCB that are needed.


Whats that saying.... great minds think alike.
 

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Discussion Starter · #5 ·
Quote:
Whats that saying.... great minds think alike.
I can't argue with that!:D


Thanks,


Ira
 
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