iMac USB disconnecting

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Level 1

8 points

iMac USB disconnecting

I have a 2017 iMac and it is disconnecting my external HDD's. I have several HDD's and it just started to randomly to disconnect all of them. I keep getting error messages about them being connected and then disconnected. I'm afraid to hook them back up due to the possibility the my computer is going to corrupt my HDD's. The crazy thing is they all started at the same time so I don't believe any one is failing. I have different types plugged into different ports. Does anyone else have this issue?

Posted on Jun 30, 2020 1:04 AM

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Answer 1

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den.thed

Level 10

82,570 points

Jun 30, 2020 8:02 AM in response to Hawkjock

There is a limit to how many external bus powered drives the iMac can support. If you have three or more drives plus other USB devices, then you need to get and use a self-power USB hub that can supply external power to the third, forth or fifth bus powered drives.

You could also have a bad cord or enclosure on one of the drives that is dragging down the other drives on the USB bus. Personally I would test the drives two and then three at a time to see if I could locate a cable, enclosure or drive that is not playing well.

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Answer 2

Hawkjock Author

Level 1

8 points

Jun 30, 2020 8:38 AM in response to den.thed

I think you may be correct. I have been using this system for the past couple of years without a problem (3 drives in an external powered drive bay that can hold 4). I only turned on one drive today and so far there has not been an issue. I will trouble shoot each drive to see where the problem lays. Thank you for the reply.

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Answer 3

Hawkjock Author

Level 1

8 points

Jul 4, 2020 3:27 AM in response to den.thed

Ok, it's been a few days and I haven't had any issues. It appears that one of my drives was indeed dragging the whole thing down. I have two out of three working fine. As long as I don't turn one of my 4TB drives the others work great.

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Answer 4

den.thed

Level 10

82,570 points

Jul 4, 2020 7:00 AM in response to Hawkjock

Glad to hear that all is working fine.

Sound like you need a good "Self-Powered USB 3.0 Hub" to help power your third and forth drives.

for examples > https://www.amazon.com/s?k=powered+USB+3.0+hubs&i=electronics&ref=nb_sb_noss_2

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Answer 5

Hawkjock Author

Level 1

8 points

Jul 4, 2020 7:45 AM in response to den.thed

I have one of those for some peripherals, but I am using the Mediasonic 4 Bay Dock for 2.5" / 3.5" SATA HDD/SSD - USB 3.0 & eSATA Support 12TB HDD for the HDD's. I think one of the HDD's is going bad. I'm going to plug it into another bay I have and see if it disconnects.

https://www.amazon.com/gp/product/B0078H8L04/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

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