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External HDD won't power up on iMac, will on PC. Why/fix?

C

cognus

macrumors member
Original poster
May 1, 2012
75
2
Texas
a Friend's iMac, circa 2015, in good shape, runs what it should, but the Seagate 2TB Time Machine drive 'stopped working'. I moved it around between 2 of the USB ports and it would not get the power light on, and of course would not mount. So I assumed the worst. But, plugged it into my ordinary pc laptop and the light comes on, Disk Mgmt shows healthy drive with 3 partitions.
I'm puzzled as I've never seen an iMac that lost power to its USB ports. The keyboard is in one USB port and is working..

This one did mount and work properly in the recent past - Time Machine app shows a string of updates

pls give me a debug step or two
 
Does it show up unmounted in Disk Utility? Or, will it not even spin up?

Also, can you give more info about the drive? I am assuming it is a 2.5" HDD, but clarifying might help figure out stuff.

cognus said:
I'm puzzled as I've never seen an iMac that lost power to its USB ports. The keyboard is in one USB port and is working..
Click to expand...
The keyboard only uses a small amount of power compared to a HDD.
 
cognus said:
a Friend's iMac, circa 2015, in good shape, runs what it should, but the Seagate 2TB Time Machine drive 'stopped working'. I moved it around between 2 of the USB ports and it would not get the power light on, and of course would not mount. So I assumed the worst. But, plugged it into my ordinary pc laptop and the light comes on, Disk Mgmt shows healthy drive with 3 partitions.
I'm puzzled as I've never seen an iMac that lost power to its USB ports. The keyboard is in one USB port and is working..

This one did mount and work properly in the recent past - Time Machine app shows a string of updates

pls give me a debug step or two
Click to expand...
Have you tried rebooting the imac? I've found this solve various external HD issues
 
Tell us about the hard drive.
Is it a 2.5" or 3.5" drive?
Is it a platter-based drive?
Or... is it an SSD?

IF it's a 3.5" platter-based drive, the enclosure should have a power supply block.
If so, is your friend using it?

Have you tried an SMC reset on the iMac?
 
Juicy Box said:
Does it show up unmounted in Disk Utility? Or, will it not even spin up?

Also, can you give more info about the drive? I am assuming it is a 2.5" HDD, but clarifying might help figure out stuff.


The keyboard only uses a small amount of power compared to a HDD.
Click to expand...
nope
the drive is a Seagate Backup Plus Ultra Slim ostensibly '2TB' drive https://www.seagate.com/search/?keyword=SRD00F1
 
Rich B22 said:
Have you tried rebooting the imac? I've found this solve various external HD issues
Click to expand...
yes, but after returning to my office it did occur to me that we should do a full power/off, bleed the registers/capacitors, back up again. As said, it looks healthy, powere-up with no issues on my little asus laptop, but of course I'm not messing with the formatting so all i know is the interrogation looks 'good' - formatting looks as it should.
I guess if nothing else seems to produce, a powered hub might be in order. but it is odd because there shouldn't be that much variance between the usb power on that vs any other usb 2/3 channel unless something went 'tilt'
 
image of minitool part wizard, see bottom drive here
I assume it is showing that partition 'other' because it is formatted APFS... but ain't sure. on this particular system i would be very surprised if its is max'd out.
but am I wrong?? I thought Time Machine wanted exFat, which minitool should be able to id
minitool-seagatedrive.png
 
OP:

Did you say you mounted the drive on a windows PC and it mounted ok?

Is there ANOTHER MAC (other than the original owner's) that you could try the drive on?

If you put the drive into my hands, I would
a. connect it to another Mac
b. open disk utility
c. see what du shows you re the drive
d. if there were multiple partitions, I'd click on each one in disk utility and then click "first aid" and let it run.
 
Do you have anything else plugged into the other USB ports that would be drawing significant power? I know that when I hook up multiple bus powered devices then some won't start/work if the ones already connected are drawing toward the limit of what the ports can deliver. Course I get a little error message telling me to disconnect something, which I assume you're not seeing.
 
cognus said:
This one did mount and work properly in the recent past - Time Machine app shows a string of updates
Click to expand...
Just curious -- between it working, and now not working, did he do an upgrade to Monterey?

(I've had some odd problems with external drives once I upgraded, and I've read SO many posts from others that I'm almost convinced there are some bugs in Monterey relating to external drives.)
 
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