iMac hard drive damaged...need advice

[mgbrian17]

I work on computers for a living but have never worked much with hard drive electronics or mechanicals. I have a hard drive that was removed from an iMac that was supposedly struck by lightning and the user would love to retrieve as much data off it as possible. The drive is a WD3200AAJS 320 GB Caviar SE made in Thailand and if I try to boot up a system with the drive installed the system power supply light flashes but will not power up. The original iMac does power on and the screen works also but nothing else. My thought is that the drive has a short circuit on the controller board and after reading your article (recommended for newbies) about the construction of the controller board I wondered if it would make sense that the TVS diodes had shorted out and, if so, maybe they could be replaced and make the drive operational? The controller board part no. is 2061-701444-000 AD. If anybody here has any advice it would certainly be appreciated.
Thanks, Brian

[poehere]

If you want to know they are shorted then take a volt meter and test them. They can easily be removed. So tell me how did it get struck by lighting on this one. Or are you referring to a lighting storm and a power outage on this one. Oh well anyway check with a volt meter if nothing else is damage on it then try removing them and see what happens after wards on it. If this is not the problem then you need to change out pcb on it but this requires moving adaptive data from ROM to the new board to make it work again. Each board on this series holds adaptive data in the ROM.

[mgbrian17]

Thanks for your quick reply Iorana. I am not sure of the exact details of the lightning strike but I assume they mean lightning hit the house the iMac was in and it has not worked since. I do not know PCB electronics that well so how would can I tell which are the TVS diodes on this particular drive? Or maybe what I should ask is where could the board be sent and either tested or repaired? I can do some low level stuff but I am not skilled at PCB level repair.

[fzabkar]

If you upload a detailed photo, someone will identify the suspects for you.

The usual culprits are D4, D3, R67, and R64 near the power connector. Assuming there is no other damage, a repair involves cutting out the shorted diode and soldering a wire or a solder blob in place of the open resistor.