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 Mac Mini Audio Trouble |
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 Tue 8 Feb 2005, 05:28
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Newbie
Group: Members
Posts: 9
Joined: 01-Feb 05
From: Gainesville - DE
Member No.: 59,616
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No luck, guys. I tried moving the brick as far away from wires as I could, then I tried plugging into a wall outlet instead of a power strip, and then I tried plugging into a different power strip. Same result...  I think it's time for AppleCare to the rescue! JBeat
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Tue 8 Feb 2005, 15:25
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Junior Member
Group: Members
Posts: 191
Joined: 17-Aug 04
From: London - UK
Member No.: 48,982
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Do you have a test meter or an oscilloscope...you could measure DC levels coming from the power supply, check the rails as it were. You can also measure the AC present on DC rails, this would be called 'ripple' and will cause hum, noise, buzz etc in equipment, seeing it on a scope is a far better method as the visual feedback of a jagged saw like DC rail instantly tells you why your unit sounds pants!! Measuring it 'under load' ie plugged in and switched on, is preferable as psu's will often be fine when they're not 'stressed' but will go west when something is asked of them..
Can you tell what the psu puts out, one rail, two or more, what the rating is etc? If it only puts out one rail then there must be some kind of regulation board inside the minimac..Never seen one, I should imagine it's a little switch mode supply..
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It didn't take the AppleCare rep very long to isolate the problem, and it turns out that there was nothing wrong with my Mac Mini, or its power supply. The rep had me take out the bluetooth usb device that I was using for my Apple bluetooth wireless keyboard and mouse, and hook up a wired usb keyboard and mouse that I had. As soon as I booted back up, the buzz was gone. I had the bluetooth device in the usb port right next to the headphone jack, and I guess it was causing interference. The easy solution was to move the bluetooth device to my usb hub on the other side of the desk, and the buzz is gone. Sometimes we overlook the easy things while looking for the complicated. Thanks for all of your responses, it's good to know you guys are there to help. 
that's a new one on me!