Causes for blown drive chipI s

[puterboy]

I (stupidly) had 2 120GB Maxtor drives go up in smoke (with an accompanying yellow flame on one of them).

I was accessing the drives using an external PATA-to-USB converter, swapping back and forth between the drives.

Then when I was just about finished, one of the drives didn't spin up and I noticed a faint burning smell.
Being *stupid*, I plugged in the second drive and it too didn't spin up but this time there was more smoke and a noticeable flame. On examination, both drives had burn marks to what I believe is the power controller chip (labeled SMOOTH and manufactured by ST)

I can't however figure out what suddenly caused this to happen in 2 separate drives spaced 5 minutes apart:
1. The PATA-to-USB converter was working fine on those same drives just minutes before
2. The +5/+12 voltages all tested out fine (5.2V and 12.9V unloaded) before and after. Also, no voltages in excess of about 3.3v on the data connector.
3. There were no metal contaminants or obvious shorting materials around
4. A transient or electrostatic shock seem unlikely to separately affect 2 drives spaced 5 minutes apart.

So other than having been stupid in burning the second drive, I can't figure out for the life of me what caused them to suddenly fail and go up in smoke after working back-and-forth all night.

Any suggestions on what went wrong and what I can do to troubleshoot the problem to make sure it NEVER recurs?

Thanks!

[jono-ats]

I've found that the power supplies for some of the USB adapters have terrible regulation.

I once hooked a Hitachi drive to one of these things, right in front of a customer, and it SMOKED. (Does your adapter-thingy have an anodized purple body, by chance?)

I haven't tested this, but I wonder if a high current load causes the supply to put out too high a voltage in compensation? it would be interesting to measure the voltage under load, with a scrap drive of course . . .

The USB adapters have circuitry inside and perhaps that is where the problem lies.

[puterboy]

Well my real problem is that I was actually using 2 different PATA->USB adapters both of which had been working and now I'm not sure which one caused the actual damage.

Interestingly, on one of the drives, after it had just smoked a little, I tried it back in the computer and then it smoked more and started flaming. So the net of it is that since I wasn't paying attention initially, I'm not sure which of my adapters is bad. I guess I should just assume they both are.

Regarding regulation, I didn't notice any AC voltage on the adapter but that doesn't tell the whole story of course.

[BlackST]

Low cost - high problems. I don't trust chinese low cost ps... Chinese are very skilled in fireworks making, in fact...

[mediaman]

these crap usb housings are a real money maker for DR pro's! I have almost paid for *some* of our investment thanks to them