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I just got this PC fan and it has a 3 pin connector, I know the wire with the white stripe is positive but how can I find out which of the other two wires are negative?

If you can't see the photo, here is a link to it: https://i.stack.imgur.com/QQYmk.jpg

Fan cable

Exoon
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  • A photo might help. – Anindo Ghosh Apr 29 '14 at 18:25
  • There is a big photo? Can you not see it? – Exoon Apr 29 '14 at 18:29
  • Added a link to the photo if you can't see it for some reason. – Exoon Apr 29 '14 at 18:31
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    Just a note to help you further: I realize that in this case you photographed the wire with its markings clearly visible, because (I assume) you think they are the most important. However, in this case the fan itself and the connector on the end of that wire are actually more helpful. The fan would show, presumably, its specifications. The connector (or lack of) would answer the question of how to help you hook it up. If it has a typical PC fan connector, one can assume that it is conforms to a known standard. – JYelton Apr 29 '14 at 19:26
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    The wires themselves are marked with information about their composition and insulation properties, which tell you what applications they can be safely used in. However the markings applied by the cable manufacturer may or may not serve any purpose to the device manufacturer. In other words, the white stripe *could* be used to indicate something, but unless the fan manufacturer states such a usage in a datasheet, it doesn't really help. If the fans are hand-soldered or something, the white stripe could actually vary from fan to fan! – JYelton Apr 29 '14 at 19:28

2 Answers2

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PC fan pinouts can be found easily online:

PC fan pinout

If you're trying to figure out which wire is ground on the fan itself, and you don't have a connector, then just connect 12V to the middle wire and try ground on either of the outside wires. When the fan spins, you've found it. The other, if connected, is a tachometer. Connecting it to ground briefly won't cause any harm.

JYelton
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  • On my fan isn't the outside cable with the white stripes the red one? My 12v PSU has red and black i was assuming connect the red on the PSU to the striped wire on the fan. Sorry i don't know much about this stuff. – Exoon Apr 29 '14 at 18:36
  • This image is different: http://www.overclockers.com/forums/attachment.php?attachmentid=92907&d=1300219923 – Exoon Apr 29 '14 at 18:40
  • @Exoon Actually, the image is flawed. It shows the same pin (2) as positive, but the colored wires at top left are incorrect. White stripes don't necessarily mean anything - the manufacturer might have just used what was available, and the white stripe might be for the tachometer or was ignored completely. – JYelton Apr 29 '14 at 18:53
  • Ok i see, If i get the wires the wrong way around will it do anything bad ? – Exoon Apr 29 '14 at 18:57
  • I've connected lots of PC fans backward by accident. Sometimes they spin in reverse, sometimes they don't do anything. It depends on the type of fan. I've never damaged one with reverse polarity. YMMV – JYelton Apr 29 '14 at 19:02
  • Yeah i don't mind too much about the fan breaking, It won't go bang or trip the switch will it? – Exoon Apr 29 '14 at 19:10
  • If this is a standard fan for computer ventilation, it's going to be rated for 12V and probably between 250 and 1000 mA. What are you powering it with? A simple, cheap 12V wall transformer will be just fine. The pins on a computer motherboard will ensure you connect it correctly, assuming that the fan has the appropriate connector. – JYelton Apr 29 '14 at 19:14
  • Yeah im powering it with a 12v 1a adapter. There are some symbols on the connector that came with the fan, Do they mean anything to you : https://www.dropbox.com/s/i31xm8yhqhqw5qm/2014-04-29%2020.15.04.jpg – Exoon Apr 29 '14 at 19:16
  • TKG is a manufacturer, like Molex, that commonly make those connectors. They aren't related to the operation of the fan. – JYelton Apr 29 '14 at 19:17
  • ok thanks, i tried it one way and the fan made a little noise then smelt abit of burning, Was only plugged in about 5 seconds, tried the other way and its working ok now. Will the fan still be safe to run 5-6 hours a day after the smell and noise? – Exoon Apr 29 '14 at 19:36
  • Impossible to answer without knowing more about the fan itself. Consider a new question, but ultimately you need the datasheet for it. – JYelton Apr 29 '14 at 19:38
  • Sorry i meant to say after the smell, Could i have damaged something ? – Exoon Apr 29 '14 at 19:38
  • let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/14222/discussion-between-exoon-and-jyelton) – Exoon Apr 29 '14 at 19:41
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3 pin pc fan connector

P.S. It would be much simple to answer if upload again a picture showing terminals of the wire. Else try get it from pin connector.

Nick Alexeev
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fadooengineer
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