MacBook don't see external gard drive with two wires

[jjur]

Hi,

I have 3 external hard drives:
- two with double USB wire
- one with only one USB wire

My MacBooks (Pro 13 and 13 white) don't see the drives with double USB wires. Both MacBooks work perfectly fine with the drive with one wire and my windows machine works with all 3 external drives without any problems.

Any idea what the issue could be?

 

[gsahli]

Can you explain to us what "double USB wires" means here? One connected to a Mac, one connected to a PC?
Have you ever been able to use (read & write) each of the drives when just connected to a Mac? What is the drive format of each?

 

[xlii]

Some external usb enclosures come with a dual usb cable. One end plugs into the enclosure. The other end splits into 2 usb connectors that are meant to plug into the laptop or computer. The 2 usb connectors are not the same. One of them is only connected to the power pins of usb. The other is a full usb connector. It is only useful if you are connecting to low power usb ports where it would take 2 of these low power ports to power your external drive.

 

[jjur]

Some external usb enclosures come with a dual usb cable. One end plugs into the enclosure. The other end splits into 2 usb connectors that are meant to plug into the laptop or computer. The 2 usb connectors are not the same. One of them is only connected to the power pins of usb. The other is a full usb connector. It is only useful if you are connecting to low power usb ports where it would take 2 of these low power ports to power your external drive.

This is exactly what I meant by "double USB wires".

 

[Samuriajackon]

This is exactly what I meant by "double USB wires".

I never got that to work with ANYTHING. I remember doing this long ago with old USB stuff and all i can come up with is that the drives use to much power to carry signal for both devices. It's not like Firewire, it's USB one drive at a time is how I had to do things.