On 2014-09-08 Dan Martin wrote:
re the external mechanical drive: When plugged in to power and USB, it makes a faint beep, on for a couple seconds then off for a couple seconds - this sequence repeats 2 more times then it is silent.
Sounds like dead motor (is it spinning?) or dead/locked-in-park heads. Or the heads crashed on a super-critical area of the disk.
Your next step may be cracking the drive open to see what the heads/platter is doing. Sure, that's the last gasp, but I do it all the time and sometimes I can get things going again to get some data off. (Clean room schmean room.)
I have not tried any drive diagnostics - I have not done it on a Mac before.
In theory an Intel Mac should be able to boot normal x86 boot CDs for disk diags. Unless the Mac BIOS does something stupid to make that impossible (wouldn't surprise me). You'll have to ask/google Mac people. My fave utility for this is UBCD which has all the mfr's diags on one disc that manages to boot on more systems than the originals!
Can you do this through USB?
No. Diags don't run through USB.