07 May 2007

A Hard Dive Headache

This isn't exactly programming-related per se, but I present henceforth my story demonstrating how hardware compatibility issues trump software compatibility any day!

I have a PC and a Mac on my desk at home.

I have a small handful of spare hard drives I use to back up these computers plus two laptops.

I try to buy hard drives when they hit a price bang-for-buck "sweet spot" -- this year, that is in the 250G range; a couple of years ago, it was in the 40G range. So I have a couple of 250G La Cie enclosures. I also have a couple of fanless "Mad Dog Multimedia" enclosures which I bought empty and filled with Seagate 40G drives. They're both USB/FireWire, which is ideal for moving things around between Macs and PCs.

All of them come with external power bricks. The power bricks for all four drives are nearly identical, physically, black boxes with removable AC cables and attached DC cables. The boxes have little green LEDs. They all have identical DIN-4 round 4-pin connectors. These have a little notch on one side and a flat spot on the other, to make sure you orient them correctly when you plug them in, and identical DIN-4 connectors that plug into the drives.

They're all plugged in to power strips on my desk.

The "Sunpro Powmax" bricks that came with the Mad Dog enclosures have a little diagram on them that looks like this (sorry, I don't have a digital camera that will zoom in close, or I'd take a picture).

            _____ 
          /       \
GND ---- | *     * | ---- GND
+12V --- | *     * | ---- +5V
          \       /
           --__--

On the diagram above, the flat side of the connector is shown at the top, and the little "notch" is not shown, but it goes at the bottom.

The LaCie bricks, on the other hand, made by "Sunfone" instead of "Sunpro," have a little diagram that look like this:

     --  ---
    /  \/   \
2  | *     * | 1  PIN 1:5VDC
4  | *     * | 3  PIN 2:12VDC
    \_______/     PIN 3:GND
                  PIN 4:GND

Where the flat part of the circle is at the bottom and the little notch is at the top, although this is actually pretty hard to distinguish in the diagram.

I'll flip them around for you so the orientation of the circular connectors is the same, and label the pins more clearly:

    __-----__           __-----__
  /           \       /           \
 |   G     G   |     |    G    G   | 
 |  +12V  +5V  |     |   +5V  +12V |
  \           /       \           /
    -___/\__-           -___/\__-

Just let that sink in for a moment.

It took me a while to guess why my hard drive, a 250G La Cie drive, wouldn't mount. Finally I started looking at the power bricks. You know that feeling you get when you find out that you've just broken something expensive?

I guess it could have been worse; it could have fried the PC's motherboard too, via the USB port. Who designs this crap? (I know who builds it, but I can't very well blame this on the manufacturers in China; it appears they both did a wonderful job manufacturing exactly what was specified).

Both power supplies have all the appropriate regulatory agency approvals: CE, FCC, UL, and some others I don't recognize. But, of course, they don't actually conform to any particular wiring standard.

After determining that the La Cie drive was out of warranty, and given that the warranty was unlikely to cover this kind of idiocy, I decided to try opening up the enclosure in the hopes that it might have some kind of fuse that I could replace, and that the drive itself was OK.

Surely they must have some kind of fuse in the enclosure's circuitry, right?

I'll bet you a new hard drive that they don't.

Well, the La Cie enclosure is a pretty nice enclosure, but it isn't designed to come apart. They have part of the drive covered with an easily torn (yes, I should know) adhesive foil, and mounted on some kind of sticky silicone anti-vibration pad. I could try stuffing a new drive in it at some point.

The dead drive smells like burning plastic. There's one little surface-mount component on the back that is visibly burnt. If this were 1980, with my knowledge I gained putting together Radio Shack 250-in-one electronic experiment kits, I would be able to tell you if it is a resistor or a capacitor or a diode. If this were 1980, I could probably even solder on a new part. But it is 2007 and all the little black parts look the same, and even if I could find a replacement component I doubt I could solder it on.

Needless to say, the drive would not spin up when I put it in the "Mad Dog" enclosure.

So I put the 40G drive back into the "Mad Dog" enclosure, and powered it up.

I'll give you two guesses which kind of power brick I plugged it into.

My office smells like burning surface-mount components. There's a nearly identical little burnt component on the other drive. It's in a slightly different place on the 40G drive.

I had some files on those drives that I wanted. The 250G drive had mostly unimportant stuff, but a few gigabytes of important stuff.

I'm no fool. I kept a backups of that handful of important files.

On another hard drive. Guess which one?

I've got a headache.

I can't in good conscience ask Seagate to fix them under warranty. Can this kind of thing even be repaired any more? It seems like it should be possible. But I'll have to look into that later.

I'm going to bed. Ever feel like you want to yell at someone for being an idiot, but the only one you can find is between your own chair and keyboard?

5 comments:

Jon said...

Well, you may be in luck.
You can swap the drive electronics from a working drive to a dead drive. If you are lucky enough to have two 40gb drives which are the same model.
( Dont forget to backup the contents of the working drive :) Then it is a simple matter of unscrewing the boards and swapping them, and crossing your fingers.
I have done this, but not recently. I think they were more like 8gb drives.
The same goes for the 250gb drives.
However, when people talk about this they always moderate with the comment that 'modern' drives wont accept alien boards. Doesnt _seem_ to be the case.

Paul R. Potts said...

Thanks for the suggestion, Jon. It could work, but I think the little logic boards on the drives actually have flash on them to store the bad sector map.

I don't know yet whether this will work, but this morning a kind co-worker with more knowledge of hardware than I possess looked at the burnt parts under a microscope and did some testing with a multimeter. He tells me that they are (I think he said) voltage-protection diodes wired in parallel with the 5V circuitry. He suggested just removing them, on the grounds that the 5V logic circuitry may be intact. After removal, the two sides seem to present reasonable-looking numbers to the multimeter. So there is a chance that tonight I might be able to get one or both of the drives working long enough to copy off the data. File this under the category of "don't try this at home" since presumably if something went wrong I could start a fire, so I will have to watch them carefully.

If it works, or if it doesn't, the smoked drives will get disassembled and get their platters hung on the wall as a warning to help keep the other drives in line!

Paul R. Potts said...

Good news -- after removing the fried voltage protection diode, at least one drive spins up and mounts under Ubuntu. I've got a big file copy going on across Samba. I'm keeping my fingers crossed that the other one will also work, but it looks promising!

Paul R. Potts said...

A final note: I managed to get all the data off both drives!

Dan said...

Wow, congratulations. I think I speak for all your readers when I say I feel your pain and am relieved you got your data back! And that's a nice trick to be aware of.