Hitachi 4TB HUS726040ALE614 No Power

[managerharry]

Got a Hitachi 4TB HUS726040ALE614 from a G-Drive enclosure. PCB PN: 0J50178. No signs of life when power is connected. PCB has no signs of damaged or burned components and nothing heats up when power is applied to bare PCB. Thinking PCB + ROM swap. Suggestions? Thanks.

[managerharry]

I don't have firmware tools unfortunately. Here's a pic

[fzabkar]

Check that PUIS is not enabled. You can disable PUIS with HDAT2.

Check the TVS diodes and fuses.

Attachments

TVS_fuse.jpg (77.6 KiB) Viewed 11854 times

[mhp666]

What is the function of the 2-strip component between the fuse and the tvs of the 5-volt line?

[Tomset]

https://docviewer.yandex.ru/view/454118 ... J9&lang=en

[managerharry]

fzabkar to the rescue once again. thank you for the tip! I should have caught that myself... next time.

12v fuse and 12v tvs diode were both toast. replaced them & bam, drive up and running. extracting the data now.

Thanks to everyone else for the other suggestions as well!

[fzabkar]

What is the function of the 2-strip component between the fuse and the tvs of the 5-volt line?

That appears to be a Schottky rectifier diode. Often it exists on its own, without the parallel connected TVS diode, in which case it provides protection from reverse polarity. However, I confess that I don't understand why it is needed in this case since the TVS diode should provide the same protection and more. :?

BTW, automotive equipment often has "d*ckhead diodes" to contain the damage in case the user reverses the polarity of the battery.

[mhp666]

That appears to be a Schottky rectifier diode. Often it exists on its own, without the parallel connected TVS diode, in which case it provides protection from reverse polarity. However, I confess that I don't understand why it is needed in this case since the TVS diode should provide the same protection and more.

BTW, automotive equipment often has "d*ckhead diodes" to contain the damage in case the user reverses the polarity of the battery.

hanks for the info.
I would have seen logic in a capacitor, as a low frequency filter.