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tmhudg

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About tmhudg

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    New Mac Geek
  1. Well, that's a fair question. Basically, re-soldering that tiny diode back onto the board is probably beyond my skills. The tip of my old soldering iron is bigger than the whole diode itself. I don't think I would trust the drive even if I could put it back together. I'm not really sure what caused the diode to short in the first place. Conceivably, it could be something on the drive that will fail again. If I managed to re-solder a diode to the board but it didn't work quite right for some reason and the spike happened again but the diode didn't protect the system Power Supply, things could be even worse. So basically, I just think the drive is not trustworthy enough to use. I dodged a bullet and was able to salvage the data so I don't want to temp fate any further. Tom
  2. Hello, I recently had my hard disk fail but I was able to fix it with an easy hardware hack. This could save you from data loss or big money on data recovery so I figured I would recount my story here. I was sitting in front of my computer (a Hackintosh I built a few months ago) doing nothing really - I was actually focused on my laptop - and it just turned off. No warning, no errors, just "lights out". I tried turning it back on and it would not power on. I opened up the case to see if any fans were spinning - nothing. I pulled the power cord out and re-plugged and hit the power button again. This time, the CPU cooler fan spun a few revs and then stopped. No boot. It wouldn't even spin again unless I pulled the power cord out and re-plugged. Still only spun a few revs and stopped. So is it a dead Power Supply or a blown Motherboard - Hmm. I unplugged the two internal disks - 1 SSD boot disk and 1 HDD data disk. Powered on and it came up to the boot menu looking for disks. I plugged power into the SSD boot disk and the system booted. Still wasn't sure if it was a bad data disk or if the extra load it was adding was killing the PS. So I took the HD out and put it in an external enclosure. It would not turn on at all. Okay so, bad HD. Of course I had Time Machine backups of my data disk so I restored back to a new HD and was all set... Except that I actually didn't get *everything* back. I had excluded some folders from the Time Machine backups - raw video files, Final Cut Event files, etc. I consciously made this decision and I didn't really need these files but after *not* getting them back, I began to regret losing them. So, since the HD didn't seem to die a slow, agonizing death but just wouldn't turn on, I thought there was a good chance the data on it wasn't corrupted and there might be a way to get it to turn on. To the Internets! Turns out that my symptoms fit the profile of a disk "failure" where the TVS diodes, located on the HD circuit board, sacrifice themselves to save the disk in the event of a power spike. These diodes - one for 12 volts and one for 5 volts - act kind of like a fuse to protect the disk. Instead of opening like a fuse though, they short. This short causes the Power Supply in the computer to detect the over current and shut off which explains why the computer would not turn on. The "fix" is to snip the lead on one or both of these shorted diodes to open the circuit again and allow the HD to power on. With nothing to lose, I checked the two diodes with an Ohm meter, found the one that was shorted, snipped it and put the disk back in the enclosure. I turned on power, the disk spun up, mounted and I was able to copy the files that I had not backed up, back to my new data disk. w00t! Obviously, that disk is now not protected from spikes so I'm going to throw it away but at least I was able to use it long enough to recover data from it. So I wanted to post this long (sorry) story to hopefully help someone who might be in a similar situation. If you don't have backups and are faced with a potentially huge bill for disaster recovery, this might save your bacon. Here is the link that provided the most useful information regarding this problem. http://www.users.on.net/~fzabkar/HDD/TVS_diode_FAQ.html Tom
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