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User profile for user: unimatrix7
unimatrix7 Author
User level: Level 1
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iMac would not detect any external powered 3.5 " hard drives

Hi,


I noticed that my iMac osx 10.6.8 is not detecting any of my 3.5" external hard drives. The finder would not detect it and i tried using disk utility to check if the mac does. To my dismay, it did not.


I have 2 , 2 T Buffallo 3.5" external hard drives, they worked fine and one day they were not recognised. Initially i thought my buffalo drives crashed, but thank goodness it worked fine on my media player box.


Next I a 1 T Seagate Free Agent desktop which is also a 3.5" (acts as my time machine) and worked fine. Today I wanted to perform a back up after a few weeks, Mac again did not recognise the hard drive. I tried plugging and unplugging the usb, each powering up and down the drive between 1 min intervals. Did this twice, still no recognition.


I thought my usb port to my mac is off, but i could plug my iphone 5 usb and the port is working. I had also plugged in a 2.5" external Buffalo mini station 1 T hard drive, mac recognised it and i was able to transfer huge files.


Am a lil lost, so apprciate some help if anyone knows what to do please.


thanks!

Posted on Jan 30, 2013 5:14 PM

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5 replies
User profile for user: unimatrix7
unimatrix7 Author
User level: Level 1
0 points

Jan 31, 2013 6:07 PM in response to BDAqua

Hi BDAqua,


Thanks for replying. I don't think it's the power supply issue as the drives power up for a while and powers down because the mac doesn't recognise it. I tried using another power adapter same issue.


If the power supply unit u are talking about is in the hard drive itself. Again no issue as my media player unit (AC Ryan) can detect my drives and play the video files in it.


I have been trying to search for tools to diagnose if my USB ports in my mac are stuffed. I am not a techie so am lost.


I have also done a disc verification using disk utility and the result was all good.


Appreciate if you got any more ideas abt this issue.


Thanks!

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User profile for user: BDAqua
BDAqua
User level: Level 10
239,585 points

Feb 3, 2013 3:55 PM in response to unimatrix7

reset FW bus, same goes for USB reset...

Reset the Firewire bus

If your Firewire or USB isn't recognizing any device. A solution which has worked for some whose hard drive became invisible in 10.4 was simply to follow these four steps to reset the Firewire/USB bus:

1. Shut the machine down.

2. UNPLUG the power lead to the computer and any firewire/USB drive.

3. leave it for 10 minutes.

4. Connect back up and reboot.

http://www.macmaps.com/firewirebug2.html

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User profile for user: unimatrix7
unimatrix7 Author
User level: Level 1
0 points

Feb 4, 2013 4:38 PM in response to BDAqua

Hi BDAqua,


Thanks so much for your advice. *2 thumbs up* The mac finally recognised my 1 TB Seagate and is now backing up through time machine.


However it was not recognising my 2 TB Buffalo, when i plugged it in, it kept beeping intermittently. I thought it was disc failure at first (was very upset) but it played fine on my AC Ryan.


Anymore advice you can give? 🙂


cheers!

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iMac would not detect any external powered 3.5 " hard drives

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