Firewire Bus Power - Un-needed

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Level 1

4 points

Firewire Bus Power - Un-needed

I've been using an Echo AudioFire 12 firewire interface for years with my Mac Pro, but now I'm using it in the field with my MacBook.

The AF 12 is (AC) self powered yet the MacBook automatically sends it bus power, thusly running hotter and the fan never stops.

If I plug in a 6 pin FW cable to the MacBook and leave the other end un-attached the fan never turns on. When I plug in the AF 12, the fan starts up (within a few minutes).

Or is there a way to disable Firewire bus power on the Mac (10.6.5). Or can this be achieved using a cable that doesn't send power.

Any suggestions?

Thanks!

MacBook, Mac OS X (10.6.5)

Posted on Dec 1, 2010 1:48 PM

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Answer 1

analogcabin Author

Level 1

4 points

Dec 2, 2010 5:55 AM in response to analogcabin

Anybody?

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Answer 2

Dec 2, 2010 9:26 AM in response to analogcabin

Someone may know of a way to disable power on the macbook side of things, but I don't know how. I do know that if you use a 4-wire FireWire 400 cable it will not send power, and that they do make 6-pin cables that don't have power pins connected. It looks like the AudioFire 12 does not have a 4-pin FireWire port, but you may have some luck with a 6-pin cable that doesn't have power pins. This may not fix the issue, however, as depending on how many system resources are consumed by the AF 12, it may just be using enough CPU cycles or taxing the FireWire interface enough to kick the fan into high gear.

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Answer 3

analogcabin Author

Level 1

4 points

Dec 2, 2010 9:34 AM in response to TheWattsMan

Ya. Someone suggested trying a Port isolator cable or a 6-4 cable with a 4 to 6 adapter.

I just thought I could nip it at the source

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Answer 4

Dec 6, 2010 9:51 AM in response to analogcabin

How do you know your MB is sending it power? It should not send power if the device does not need it.

The fan inside the MB is to cool the MB CPU and GPU, suggesting it is the MB doing something becuase you connected the FW device.

The posted idea is what I would suggest as well, see what happens.

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Answer 5

analogcabin Author

Level 1

4 points

Dec 6, 2010 10:10 AM in response to PracticalMac

I bought an adapter so...... we'll see if that helps at all. My guess is probably not.
I'll report back.

Thanks!

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