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Case fans will not spin at full speed.

FireBean

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#1
I have 3 YL 120 HL's on a 360 rad. They have a direct power source that is getting a full 12v but they do not spin at full speed anymore Sure, they're quite, but I need some airflow. They started doing this after I hooked up a fan controller and the mosfet/transistor or what ever that thing was call blew because it could not handle that much current. Now, they spin at very slow speeds. Looks like about 600rpm. It's barely enough to push air through the rad. What happened and how can I fixed this?
 
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#2
Are you sure you connect them to pure +12V ?
If yes, then the fans are damaged by the previous adventure with fan controller.
Burning single coil in fan motor may result in low RPM.

However the above is quite unlikely.
Check your power source, whether it's really 12V. (and no PWM)

Cheers
 

de.das.dude

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#3

brandonwh64

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#4
If these fans are new then you might have burned the PCB some how by using the fan controller. I did this by using a fan on a breadboard. luckly it was just a test fan that I did not care about.
 

FireBean

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#5
they are directly connected to the PSU via molex. This is the same molex that is powering my 655 pump at full speed as well. I took one of the fans apart (that no longs spins at all now) and I see no physical damage. What in the world happened?

I can upload pictures if that will help.
 

Aquinus

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#6
Depending on how well sealed your case is and how many intake/exhaust fans you have it is possible that you're creating a small pressure difference that could impact fan speeds, however just because you run a fan at higher RPMs doesn't mean that it will move *that* much more air.

You also said you took apart one of the fans that failed. Everything might look fine, but it come be something as simple as poor permanent magnets inside the fan. What kind of fans and do you feel any resistance when you try to spin the fan with your finger? I have a series of 100 CFM fans and if you try to spin them you can feel the magnets resisting movement. Also have you tried using a current meter to see if power is actually traveling through the circuit?
 

FireBean

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#7
Alright, I have to break out the multimeter to figure out WTF is going on. These fans can be stopped with almost no force or injury. They are Yate Loons from Sidewinders. These are also the high-speed variants. They are not wired backwards. Also, the radiator that these fans are hooked to are external of the case. All they need to do is push air though a radiator, nothing else is going to impede their movement.

As far as the permanent magnets go, they all have the same force they did when they were new. Hell, they're only 6 moths old. I'm not wet behind the ears, so lets please the obvious solutions out like "are they plugged in right."
 
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#8
At this point I'd say they're simply damaged.
You won't see anything obvious if the coil is blown inside.