External USB 3.0 Bus Powered HDD not powering up

[Knuckleheadz]

Hi All,

I have the following set up:

iMac 27" (base i5 model)
Seagate GoFlex Thunderbolt External SSD (boot disk)
Thunderbolt to FW800 to FW400 cable connected to Edirol FA-101 Soundcard - PSU powered
1 - USB 2.0 Hub with 3x USB Hardware Dongles and Apple Keyboard & Mouse
2 - USB 3.0 External HDD (PSU powered) used for a weekly image backup
3 - USB 3.0 External HDD (with SSD installed) - contains all my audio samples

Number 1 is always powered on
Number 2 is mostly powered off and I turn it on when I get reminded by CCC to do a backup.

Number 3 is bus powered so I would expect it to come on when I power up my iMac but it never does. I have to pull the cable out and put it back in again for it to power on.

It can't be a power issue as pulling plug and re-seating it would either complain there is insufficient bus power (I would expect) or just not work.

I have an older USB 2.0 External HDD caddy that I might try it in and see if this shows the same problem.

I can't sleep my iMac as my girlfriend uses it to boot in to Windows regularly.

Has anyone else noticed this issue and if so is there is resolution to it?

Many thanks for any help or advice you can give

Jon

 

[justperry]

After you start the iMac and Login you should open System Information first and look under USB if it is recognised and look how much power it draws.

System Information is in /Applications/Utilities or you can open it by clicking on About This Mac in the Menu Bar, then More Info>System Report

 

[Knuckleheadz]

Thanks justperry, I will take a look at that when I get home tonight.

 

[Knuckleheadz]

Update for you,

I powered on my iMac and the external HDD did not power on so I launched System Report and checked the USB option as you described but it did not show there.

I unplugged the unit and plugged it back which brought it to life and rechecked System Info...

Power requirements are:

Current Available (mA): 900
Current Required (mA): 36

I will try the other USB enclosure that I have, otherwise I am stumped!

 

[justperry]

Update for you,

I powered on my iMac and the external HDD did not power on so I launched System Report and checked the USB option as you described but it did not show there.

I unplugged the unit and plugged it back which brought it to life and rechecked System Info...

Power requirements are:

Current Available (mA): 900
Current Required (mA): 36

I will try the other USB enclosure that I have, otherwise I am stumped!

Or a bug is the OS, or a User Account related problem, or a HW (the External) problem.

You could try making a new User Account, login into that account once, then restart and login into the new one again, see if it works there, if not it is or OS related or HW related (not your Mac).