3.5 External HD is not recognized [2.5 HD is]

[david mastrude]

Hi All:Any suggestion?The HD does not show in disc management or in device mgr.
No exclamation mark either.
I have replaced the enclosure.
None of my 3.5 HDs are seen.
WTF?

 

[Spykezxp]

How are you connecting it to your computer (USB)? Is it supposed to supply its own power (plugged into electric, not just getting its power from the USB)? Have you tried to use it on another computer or possibly another USB port?

 

[david mastrude]

The Blacx enclosure has its own power supply.
It is connected to a USB port.
The fact that a 2.5" HD works fine is what throws me.