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Windows 7: External hard drive connectivity lost

21 May 2012   #1
CeeGee

Windows 7
 
 
External hard drive connectivity lost

Hi

I'm having trouble with an external hard drive which connects via USB. The drive now very rarely gets recognised and the drive letter does not appear in the directory.

I have uninstalled all the USB controllers and let windows reinstall them however this has not solved the problem. I have also done a system restore back about two weeks which is when the problem started however this has also not solved it.

I have also scanned the drive for problems. I do not get this problem when the drive is plugged into another laptop using another lead.

Any thoughts? I'm running Windows 7.
Regards


My System SpecsSystem Spec
.

21 May 2012   #2
TVeblen

Microsoft Community Contributor Award Recipient

Windows 7 64 Bit Home Premium SP1
 
 

This is one of the more common problems we see here. The key information is that the drive is recognized fine in other PCs.

This indicates that your USB ports are underpowered. This is a defect and/or fault in the motherboard in your laptop which, unfortunately, is all too common also. USB specs require a minimum 5v power output. If the output drops below 5v the drive does not engage.

You can try different USB ports. Sometimes it is just one port that is faulting.

You can test to see if the problem only exists on battery power, and goes away if the power supply is plugged in.
-572848925_o.jpg

As a workaround you could purchase a powered USB hub. They also make a 2-port connector that will double the power supply that sometimes works.

But don't get too involved with toying with the OS. I doubt that is where the problem lies based upon the results you posted.


My System SpecsSystem Spec
21 May 2012   #3
CeeGee

Windows 7
 
 

Thank you for the reply

I have a second external drive which seems to function ok on the problem laptop. Secondly, the problem drive suffers the same fate on any of the laptop's USB ports.
Does this suggest something other than low power?

Regards

Clive
My System SpecsSystem Spec
.


21 May 2012   #4
TVeblen

Microsoft Community Contributor Award Recipient

Windows 7 64 Bit Home Premium SP1
 
 

It could, of course.

If an external drive is a desktop drive and has it's own power supply then the 5v issue is moot. Then the only connectivity issue is in the milivolts and not an issue at all.

But if the external drive is 'portable' then it gets it's power from the PC through the USB connection. In that case it is almost always USB power related. (Provided it works on other PCs).

The other issue I've seen with portable drives is the interface of the actual 2.5 inch drive and the plastic case it is housed in. Sometimes the connector is a cap and it is not making full contact. But that would affect it on all machines.

The biggest clue as to whether it is software or hardware related is whether Windows recognizes the drive with the familiar "Boop-Doop" (Found Hardware) sound. If you get that and then the drive is not recognized then it is on the OS side of things.
My System SpecsSystem Spec
22 May 2012   #5
CeeGee

Windows 7
 
 

Hi

Have swapped components around including power leads and USB cables. The external drive is mains powered so the power drop concern was unlikely to be the cause of the problem. Swapping mains cables did in fact not result in any change. Strangely however swapping the USB cable over to a different one has brought back stability to the unit including return of plug 'n' play functionality.

Will update in a day or two if problem reoccurs but this evening so far all OK.

Regards

CeeGee
My System SpecsSystem Spec
22 May 2012   #6
TVeblen

Microsoft Community Contributor Award Recipient

Windows 7 64 Bit Home Premium SP1
 
 

Bad USB cable. Happens.
My System SpecsSystem Spec
Reply

 External hard drive connectivity lost




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