# Help powering squirrel cage fan for iMac vent?



## Thundaar (Mar 26, 2007)

Hi,

Please refer to this post on cooling an iMac that has issues with overheating- Best way to cool your iMac

This is an expanded view of the squirrel cage blower mentioned- Sanyo San Ace B76 Blower Fan 9BD12SC6-2

These are the fans I'm deciding between, a 2100 RPM and 3000 RPM model- Sanyo Denki 109BD12MC2 2100 RPM Model

Sanyo Denki 109BD12HC2 3000 RPM Model

I would also mention to look at the response by bluescreen to brucio in the thread from 'Best way to cool your iMac'. Using this kind of switchable power adapter is what I hope to accomplish.

The problem I'm having is that these fans terminate in wire leads like that shown in the expanded view of the blower. I don't know how to make it so that I can connect the fan to a power supply brick or a 9V battery.

Does anyone have experience with these kinds of leads and making them work with standard electrical adapters? Can you please guide me on what I need and what to do?

Also, of the squirrel cage blowers I found, I think the RPMs should be adequate to resolve my problem, and I can just stick one at the top left side of the exhaust vent on my iMac so it'll keep it cool where it's generating the most heat.

Which one would you recommend for this application?

Whatever help can be provided will be greatly appreciated!


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## gcavan (Aug 13, 2009)

> The problem I'm having is that these fans terminate in wire leads like that shown in the expanded view of the blower. I don't know how to make it so that I can connect the fan to a power supply brick or a 9V battery.


AWG24 lead wires 
Red - +12V
Black or blue - 0V or gnd
Yellow - Sensor

I didn't read the entire thread. Is there a reason why you cannot plug it directly into the iMac itself? Either to a motherboard fan header (they have those right?) or to the power supply 12volt?
The unit shown on the eBay page has what looks like a standard 3 pin fan connector, though the red and yellow wires would need to be switched for use on a PC (correct me if I'm wrong, I assume Macs use the same fan connector pinouts as do PCs).
The data sheet (same for both) state a minimum 10.8 VDC starting voltage so a 9V battery isn't going to cut it.


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## Thundaar (Mar 26, 2007)

gcavan said:


> AWG24 lead wires
> Red - +12V
> Black or blue - 0V or gnd
> Yellow - Sensor
> ...


I didn't see any open connectors on the front face of the logic board, and it would require complete disassembly to reach the back of it (which is the most painful and annoying thing I've ever done when installing the 1st SSD in this iMac).

Beyond that, because everything's packed behind the screen, I have limited space to set it in. I installed 2 1TB SSDs which is probably why it's overheating a lot more now.. oddly enough. And 32 GB of RAM. I could set it on top of/near the SSD I removed the HDD for, but that's literally the only space I can put it. I'm also absolutely not confident about correctly running the connection into the motherboard. :blush:

I got most of the info I needed from the topic and the mentioned post. According to the thread, modulating the voltage should result in a change in fan speed. You may be right though. I feel I'll have to try it out.

What would your recommendation be?

I also got this e-mail reply from Sanyo-Denki. Let me know what you think.



Sanyo-Denki said:


> Between the 109BD12MC2 and the 109BD12HC2, the 109BD12HC2 will definitely give you more cooing potential since it will provide you with more airflow performance.
> 
> In order to power on the fan, you can use the mating connector for the Molex Micro-fit 4 pin connector harness that is already on the fan lead wires, or you can just remove the connector assembly and directly apply power and ground to the RED (+, power) and BLACK (-,ground) leads. If you do apply power and ground directly to the fan, we recommend the use of an ON/OFF switch on the power supply or one in-line with the battery. The YELLOW line is the signal/sensor wire which outputs the speed of the fan (Most likely you are not going to use this).


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## Thundaar (Mar 26, 2007)

Also here's an article sort of explaining why my computer's heat is going ape- New iMac Drives Not Meant to Be Replaced, And I Hate It

And pictures of the iMac's logic board as encountered when I first open it (I did think about sifting the wire through the vent hole and plugging in the fan to an external source using the voltage to modulate the speed, but I feel applying it outside to suck the air out might be more effective)- Logic Board 1

Logic Board 2


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