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Testing CPU Fan

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Mortifix

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I am trying to test my CPU fan to see if its working correctly. The fan is 5VDC and 0.36A. There are 4 cords: Red, Black, Yellow, and White. I am trying to test this fan with my multimeter if possible. Thanks.
 

Sceadwian

Banned
Attach it to a power supply that is running... If it turns it's okay, if not, it's not. This can easily be done with a case open on your PC.
 

ke5frf

New Member
Attach it to a power supply that is running... If it turns it's okay, if not, it's not. This can easily be done with a case open on your PC.


This is certainly a good go/no go test,

But I would add if it turns OK without making any unusual noise, excessive vibration or heat, and seems to be full speed it is OK.

If not, well these fans are insanely cheap so get a new one.
 

Mortifix

New Member
Sorry for waiting to reply. The fan is a motherboard laptop cpu fan so it has a special connector to the motherboard. I just replaced the motherboard and the fan no longer spins. I removed the motherboard because of possible grounding issues, but its still a no go. I was asking if there is a way to test the fan with a multimeter to see if the fan is bad before I return the motherboard for a replacement. Thanks for the advice so far.
 

Sceadwian

Banned
In the long run it really is better to spend twice the (already dirty cheap) cost for a standard fan and make sure you get a quality roller bearing one, not sleeve bearings.

And no you can't test DC brushless fans with a multimeter that I know of, the control electronics get in the way. Regardless of the different connector you can still directly apply the 5V DC to the motor to see if it spins on a known good supply. Simply use the red and black wires. and touch them to the appropriate leads on the connector, perhaps by removing them (I've done this many times) and using alligator clips on the removed connector ends. A light tough with an exacto knife to the plastic catch will easily let you slide the pin connector out of the plastic housing. They just click back into place afterwards.
 
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Mortifix

New Member
Ok I did find another fan that was a similar connector. The wires were different, but the red and black wires were in the same place as the original fan. When I hooked that one up it didn't spin either which leads me to believe its the motherboard. For future problems of a similar nature, is there a certain device that people use to test electronics like these, something that you can select volts and amps and can hook to up to live wires?

Also, is there a way to test the actual motherboard to see if the connector is getting power?
 
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Sceadwian

Banned
ALL PC's and most laptops still use a generic set of standard voltages, basically 3, 5, and 12 volt lines. 5 and 12 being typically for peripherals and 3 volt being pretty much only for the motherboard and IC's themselves. Do a search on good (and here in the forums) for modifying an ATX power supply into a bench suppy. Then you can use banana jacks as outputs and multimeter leads as contacts and you can apply a voltage to just about anything you want. As far as testing the motherboard fan connector, plug in a known working fan, that's a good test. A multimeter may not always provide reliable results because fans on motherboards are sometimes fed PWM power, rather than a steady DC.
 
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