I forgot to swap a power supply cable and fried all my drives. 5V seems to be fine, but no continuity when checking 12V. On the Hitachi drive (blue PCB) I found the bad TVS diode and removed it, but the drive still won't power on. On the 8TB WD SAS drive (green PCB), the TVS diodes all seem to be fine at least the ones I could find. Only thing I found weird was on this diode it measured .33V in one direction instead of .17. Anything else to look at?

I was mistaken, 5V is busted and 12V is fine.

After testing different things with the multi meter, looks like this fuse has a short so seems like next step would be to bridge this fuse.

The number of these which get posted. It's a shame they don't get sent in to be fixed with the same frequency.

Protection on the WD SAS (rebranded hitachi?) is top right. Check the TVS and the 0ohm resistors.


You have the right location on the hitachi but that's a mess of removing the TVS. Cleanly remove it and check the fuses (green things) around it.

Nice clear pictures by the way.

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Thank you for the tips. On the green pcb all the TVS diodes seem to be working fine, but one of the 0 ohm resistors is not working. On the other board one of the fuses is also not working so I will try bridging those. Luckily most of the data on these disks is backed up, but this has been a good learning experience. Wealth of knowledge in all the threads on this forum.

Posts look to have crossed.

The larger component you have boxed is a capacitor the left side should be ground the right on the 5v rail. The small green one is the fuse.

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Thanks for all the help so far! Recovering data from two of the drives right now after bridging the fuse highlighted in green. All the diodes were good as well as the other resistor, guessing that was for the 12V. I messed up the blue PCB while trying to test soldering, but didn't care about that drive. There is an SSD that won't power up that I can't figure out, but I probably already messed it up already. I removed what seemed to be a bad diode and I think maybe a block of those black resistors are bad, but no way I have the tools/skill to bridge those.

The SSD is one for the electronics experts - I can't follow it and the only intel SSD's I have here are 5400s and the pcbs are completely different. It's a case of following the voltage with a meter to see where the magic smoke has escaped from. I can see you've already clipped a diode off the back so not ideal.

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The blue PCB should still be OK, if there is no additional damage.

It would appear that you have removed CR105 on the SSD. This does appear to be the 5V TVS diode. If you like, we could measure some voltages and try to narrow down the fault.

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If you don't mind, I would like to try. I don't care about the data, but up for the challenge to try to fix it. I have another blue PCB that I will try to fix, but having a really hard time getting a blob of solder onto the tiny resistor without touching anything else. Don't have the steadiest hands.

Did you also remove CR206 between the 2R2 and 3R3 coils? If so, you need to replace it -- it's not a TVS diode.

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Oops, yes I thought it was. What should it be replaced with?

Put back the original one if you have it, or at least tell us its marking code. Otherwise find a fast Schottky rectifier, probably rated at 1 Amp or more.

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A backup a day keeps DR away.

I just snipped it off, so don't have the original. I'll see if I can find a replacement from another board, but that's what I get for not identifying things properly. If this is the only casualty from my stupidity, then I am lucky regardless.

For my other HDD, I may have botched things up again but this one is not powering up. What I believe were bad TVS diodes, I removed them all and verified when hooked up to the PSU they all measured correct voltages (12V and 5V). Bridged the one fuse that was busted, but not sure where to check next. I know its a pretty sloppy job, but given it is not critical I recover the drive doing the best with the tools/skill I have.

Looks like you've been a bit snip happy on that one too - fzabkar will confirm but I think you'll be wanting to put that S4 diode back far right. That first cap in the line of three under the TVS doesn't look too good either.

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Oops. I measured all 3 of them and they were measuring in both directions, so I assumed all 3 were bad. Too bad this drive didn't just blow a fuse first like the other drives. Oh well I recovered all my 8TB drives, which is nice so I don't have to try to pull all that down from my cloud backup.

The "47" component on the 0A90671 PCB is a 47uF capacitor.

The blue PCB (0A90284) appears to be one of those bad designs where the fuse protects the TVS diode and nothing much else. If I'm right, then the preamp may have been damaged.

Can you measure the voltages between ground and each of V1, V2, Vcore, +5V, -5V?

To test the preamp, measure the resistance between ground and each of the preamp supply pins. Do this with the PCB on and off the drive. When testing the resistances on the drive, you will need to locate the appropriate through-holes on the other side of the PCB. Use a screw hole as your ground.

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If you want to test the SSD, measure the resistance between ground and each of the inductors at L112 (controller side), L109 & L110 (2R2), L111 (3R3), L114 and L115 (to the right of 3R3). Do this on the 200 ohms range.

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I only got a measurement on the +5V, everything else didn't pick up anything. For the preamp pins I didn't really see anything on the other side of the board, but I measured the surrounding pins and didn't measure anything as well. Guess no point in attempting to do a moving the bios chip to another board. This drive is a 2013 drive I believe, whereas the other recovered drive were much newer so glad to see it had better protection and just blew the first resistor. The newer drives were also enterprise grade, but not sure if that really matters when it comes to the protection.

Thanks again for all the help.

These are the test points I would be looking for on the other side of the PCB. You can try higher resistance ranges until you get a reading. On two occasions I've seen a shorted preamp measure as low as 4 ohms.

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