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Author Topic: Replaced the 3-pin CPUfan of DELL Dimension 4550  (Read 1425 times)

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menno

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Replaced the 3-pin CPUfan of DELL Dimension 4550
« on: October 12, 2013, 11:25:57 AM »
Hi,
I have replaced the 3-pin CPUfan of my old DELL Dimension 4550 with a new one, brand BeQuiet (92 mm, 1800 rpm, 12 v) .
Problem is
that both wire colors and conector types don't match. So out comes the soldering iron to connect the new wire to the old connector.
/> Unaware of any wiring scematics, I just took a gamble and lo and behold, it worked. Only issue was that I kept getting error messages at startup:
"CPUfan out of reach". So I rewired, and that is where things went bad: I fried the new fan (didn't run since, and very suspicious smell). That
triggered me to do some research.

The old fan has the following markings on the fan printboard and color codes on the wires:/> S-white, G-black, V-red.

The new one (BQ) has only black wires, and the following markers on the fan printboard:
S, - (minus) and (plus).

What killed the fan was the connection order:
S to -, G to S, V to

What worked at first but with error
message was :
S to , G to S, V to -

I ordered a new fan, and would really like to know, without the risk of frying a second fan,
if the totally correct way to connect is:

S to S , G to - , V to .

Can someone help me out on this ?

kam

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Re: Replaced the 3-pin CPUfan of DELL Dimension 4550
« Reply #1 on: October 12, 2013, 11:44:38 AM »
Normally it should be for the wires
Negative - Positive - Tacho

S-white, G-black, V-red.
What you wanna do is use your multimeter to find the 12V. I bet that V is +12 and G is ground. Measure there and find the 12. The other wire could be the tachometer sensor (hence S).

I'd also suggest the same connection like you:
S to S , G to - , V to +

But first probe between V and G, you must find 12V there. Also, between S and G you must find something like 5... or 3.3.. Something like this. This is the low pull-up for the tacho feedback.

menno

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Re: Replaced the 3-pin CPUfan of DELL Dimension 4550
« Reply #2 on: October 26, 2013, 01:12:58 AM »
Thanks, that was very helpful ! . took a while (other things to do) , but I'm now typing typing on 'the subject' , the connections of the fan are OK now, as is the PC as a whole. The voltage between the S (tacho signal) an G (ground) wire is more like 7.5 V, however. What the heck, it works.
thanks again.

kam

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Re: Replaced the 3-pin CPUfan of DELL Dimension 4550
« Reply #3 on: October 26, 2013, 12:24:37 PM »
So, just to confirm for the others, can you please tell us the wires (color and letters)? Thanks!