[SOLVED] TVS Diode bad Hard Drive recovery

[pcpete]

I have a hard drive which I was looking for a client. It is not spinning up. I suspect the 12 TVS diode is bad, but it does not quite make sense. I have enclosed a picture. I made a circle on which I would guess it the suspect diode. When I test it directly I do get continuity through it. Both sides of the diode goto ground. Here is what does not make sense, shouldn't either the 12v or 5v be shorted to ground, which neither are. Is my logic sound?

I fairly feel confident the TVS diode is bad, but I wonder if something else also and I am hesitant to remove it without a better understanding of harm that may cause

 

[300DDR]

http://www.users.on.net/~fzabkar/HDD/TVS_diode_FAQ.html

Sometimes, a TVS may test "good" but still be bad. Alternatively, just get a donor PCB and move the ROM over.

 

[pcpete]

http://www.users.on.net/~fzabkar/HDD/TVS_diode_FAQ.html

Sometimes, a TVS may test "good" but still be bad. Alternatively, just get a donor PCB and move the ROM over.

if I have continuity through the diode, does not that means it is bad hands down, right? If it is bad wouldn't I have continuity between my 12v and ground and short out my psu?

 

[pcpete]

it seems like something secondary is fried. the thought is this "secondary" thing is what is stopping the short from being completed

 

[pcpete]

I just read this in the guide you posted. I suspect I also may have a bad fuse or inductor (it is a seagate)

If the drive has additional protection devices, then these may go open circuit as a consequence of diode failure. One example would be an open fuse, usually 2 amp or 4 amp. Other examples are burnt inductors in some Seagate models, and open zero-ohm resistors in Western Digital models. In such cases the drive will not shut down the PSU, but it will not spin up or be detected by BIOS

 

[pcpete]

With some guidance from a user at hddguru.com the drive is imaging as he speak. Besides the TVS diode, I had two 0 ohm resistors go bad. I just went around them by attaching a wire to a 12v contact on the board and running it out the side. If any one is curious I attached pictures with the bad resistors circled with a fat red line.