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Data recovery and disk repair questions and discussions related to old-fashioned SATA, SAS, SCSI, IDE, MFM hard drives - any type of storage device that has moving parts
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Power supply failure shorted Samsung HD204UI 5V rail to gnd

February 11th, 2020, 9:19


I was repairing a 2TB Samsung HD204UI from my old USB enclosure, using a SATA to USB converter with a separate power supply.

Unfortunately something happened either to the PCB or to the power supply, and the disk did not spin up. (I was at work and came home and HDD regenerator just said it lost the USB connection to the disk... I know, should have had the disk internally but running on 3rd laptop as 2 other machines are doing other repairs)

1. The power supply blew the fuse in a nice pop.
2. Trying to check and spin up the drive with my bench power supply with 12V and a DC/DC converter to create the 5V. I noticed high currents on the 5V rail
3. I measured the hard drive's SATA power port and found the 5V pins were all shorted to ground. (Should have checked this first...)

The board looks ok, but do we have schematics for the HD204UI (REV.03 R00)?

I need to find out where the short might be and see if it can be saved.

Best regards

Re: Power supply failure shorted Samsung HD204UI 5V rail to

February 11th, 2020, 18:03

TVS Diode FAQ:


Re: Power supply failure shorted Samsung HD204UI 5V rail to

February 14th, 2020, 18:12

Thank you fzabkar, sorry I should have updated my post! I found info on the TVS Didodes and found the 5V one stuck shorted. I desoldered it carefully with a heat gun and the drive lives again. But I haven't seen this faq before so thank you very much for directing me there!

Now I just need to find a good place to get a new diode. I want that protection. Socket Pixies are evil.

I looked at the faq and you suggested the suitable substitutes for the 12V and 5V TVS diodes in 3.5" drives are SMBJ12A and SMAJ5.0A. The one in the drive was a (On) 6V8A. The SMAJ5.0A has a clamping voltage of 9.2V. I think the 6V8A... oh, it has a clamping of 9.2V... Nevermind, I remembered wrong :) All is good
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