I just thought I'd follow-up this story with the recent developments. Historical synopsis: I had several external firewire enclosures for 2.5" drives (model ME-910U2F) die because of a faulty capacitor that tends to explode (only in a particular production run, according to sources). It is apparently only a problem if the enclosure is used on iMacs or eMacs (and an unidentified PowerMac), because they provide higher voltage (or current or something) to the firewire chain. The vendor replaced two of my dead enclosures, and I got tired of returning them when the third died, so I sought advice on fixing it.
The exploding capacitor is a small, black, radial, electrolytic style, labeled "200uF, 6.3V, 105�C". The strategy was to replace the defective capacitor, with an equivalent one of equal or higher voltage. There is not much clearance, either in width or height, so keeping the cap small was a priority.
I obtained a bag of 220uF, 10V caps (part #135124) from Jameco (first recommended by the clerk at Radio Shack, when I complained that they didn't have the capacitor I needed.) Because the several mailorder firms I looked at only give approximate dimensions for their caps, I wanted a backup in case my first choice didn't fit. They also were selling bags of 220uF, 25V caps (part #158262), so I bought some of those too. Of course the delivery cost was more than the value of the caps, but such is life--it still totaled under $10. (Not much more than the cost of mailing the dead enclosure back to the vendor.)
2 days later the caps arrived and I bought a cheap soldering iron and went to work, first removing the remains of the dead capacitor, then putting in a fresh 10V one. I installed the hard disk, and verified that everything worked fine on my powerbook. Then I plugged it into an eMac, and BANG... another exploded capacitor. This was unexpected, since presumably Jameco didn't sell me defective caps, and the original was only 6.3V !! However, these 10V caps were "mini" style (smaller than even the original), and maybe just couldn't handle what was needed.
I removed the remains of the 10V cap, and put in one of the 25V ones. They just BARELY fit, and I had to push it in place with a bit of pressure. Only a couple millimeters of clearance above, too. Verified that it worked on my powerbook, then I hot-plugged it into the eMac. No explosion. It mounted. Unmounted and hot-unplugged, then hot-plugged it back in again, and still it mounted without explosion. I rebooted and was able to boot up the eMac from the ME-910U2F, as hoped.
So, as of today it looks like I've got a working external firewire HD. It will take a LOT of repeated use before I lose the pangs of anxiety when I plug it in, and I'm still reluctant to trust much to it.
If you've got one of these exploding ME-910U2F's on your hands, and you can't or don't want to return it to the vendor (maybe you got it from eBay?), then the 25V capacitor is the one you want. They're even on clearance for $1.20 (12c each). Get 'em while they're... um... hot? Hopefully not TOO hot!
--Jim.
Imagine plugging your nice, shiny external firewire drive into your computer, and moments later hearing an explosion and seeing a jet of smoke shooting out the back of your enclosure! This is exactly what happened to me THREE TIMES.
<...long narrative deleted...>
--Jim.
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