Where to buy 3.3V 40mm fans?

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#108866 7-Sep-2012 10:31

Hi,
Does anyone know where I can buy a 3.3V d.c. 40mm x 40mm fan?

The fan in my network switch has died.
I have looked on Ebay, Element14, RS, local computer stores, Google. The only source I can find is DHgate, minimum qty 100 pcs. 5V and 12V are prolific of course.

The switch internal PSU has only 3.3V output.

I found replacement 40mm fans for specific Cisco etc switches, but there is no mention of operating voltage.

I have tried 5V fans, but they turn so slowly that virtually no air is shifted.
The switch gets too hot with no fans.

The only other option I can think of is to buy/assemble a 3.3V to 5V dc-dc converter.
Cheers,

timmmay

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#682712 7-Sep-2012 10:39

Can you not buy the replacement part from your switch vendor? What make/model is the switch?

RunningMan

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#682722 7-Sep-2012 11:05

Is there a 5v power rail in your switch?

Skolink

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#682776 7-Sep-2012 12:28

timmmay: Can you not buy the replacement part from your switch vendor? What make/model is the switch?

Its a budget brand like CNet or something more obscure so I had assumed not. I won't be home until Sunday so I can't provide that information until then. I guess it could still be possible.

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#682778 7-Sep-2012 12:31

RunningMan: Is there a 5v power rail in your switch?

No, only 3.3V, and 330V dc. I think the regulation is done on the switch PCB, to an even lower voltage.
I will check though, because if there are linear regulators on the power supply, there must be a ~4V rail.

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#684117 10-Sep-2012 21:34

There isn't any other d.c. rail on the power supply, just the unregulated "3.3V" rail that is then regulated on the logic PCB.

The switch is an Edimax ES-3132R

ubergeeknz

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#684121 10-Sep-2012 21:38

Have you tried taking the label or plug out of the back of the fan (where the bearing is) and adding a drop of 4-in-1 oil? This will often get another few years out of a sleeve bearing fan, they usually only fail because the bearing has dried out and re-lubing the sucker is all it takes. Might save you an expensive exercise!

Otherwise check polulu, sparkfun or mindkits for 3.3v -> 5v step-up converters...

Edit: oh and not WD-40 or CRC 5-56 - these will get you going for a while but will dry out after a few months.

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#684160 10-Sep-2012 22:38

ubergeeknz: Have you tried taking the label or plug out of the back of the fan (where the bearing is) and adding a drop of 4-in-1 oil? This will often get another few years out of a sleeve bearing fan, they usually only fail because the bearing has dried out and re-lubing the sucker is all it takes. Might save you an expensive exercise!

Otherwise check polulu, sparkfun or mindkits for 3.3v -> 5v step-up converters...

Edit: oh and not WD-40 or CRC 5-56 - these will get you going for a while but will dry out after a few months.

Thanks, yes. When I got the switch (2nd hand) the fan was a bit noisy, so I peeled off the label and put in some molybdenum grease. The fan was fairly well seized and hard to turn when I took it out. Perhaps I could have re-lubricated it, but I didn't think of that before I threw it out.

Thanks for the suggestion of polulu etc, I'd never heard of them. I nearly ordered a step-up converter for only US$5.45, but then when I saw the postage price it occurred to me to check Ebay, since Chinese / Hong Kong postage is often only $1. Sure enough I bought 2 units for 99c each plus $1 postage. I guess I'll get them in a couple of weeks.

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#689879 22-Sep-2012 14:36

The voltage boosters arrived, and I installed one inline with the fan. Now it is whining away like a real switch.
Initially it was rattling horribly so I peeled back the label and put some molybdenum grease in the bearing.