External Hard Drive Specs:
1TB Lacie BigDisk Extreme + USB
Inside Are (2) 500GB Hitachi Deskstars

Model: HDP725050GLA360
MLC:BA2727

PCB Card:
0A29740
BA2631

The Backstory: My friend let me use an old hard drive he had laying around and wasn't using. The hard drive is a Lacie BigDisk Extreme + USB. I formatted the drive and began using it no problem for about 2 weeks, I stored multiple projects and work files on there. Five days ago I turned on my Mac to discover that my Mac nor my PC recognized the drive.

My Recovery Steps
I did the obvious, turned off, restart, unplug, replug, tried on various other computers and got no results. Eventually I realized a hard drive inside must of failed. I never heard no clicking noises or anything strange when I put my ear to the Lacie, I could still hear a drive running. I decided to open the Lacie enclosure to see what the problem could be and quickly realized that one of the 500GB Hitachi drives was not spinning up! I stayed calm and started doing some research. I quickly learned about Lacie's power supply failures and all kinds of things including PCB Swapping and Doide testing. I started performing a few test with the drives to see exactly what the failure could be. I used a USB HD Hub to see if either drive worked, one of the two hard drives would spin up and my PC detects it but since I'm guessing its a RAID 0 config I could not take out data from only the one drive. The second drive would not spin up and was not recognized anywhere on the PC, including the BIOS. Since both of the drives are of the same model and the PCB's are the same I decided to move the working HD's PCB onto the non-working HD to see if that is where the problem was. I tested the drive that was not spinning up before with the PCB from the working drive and it worked! At this point I'm excited knowing that this could be the problem. My PC still did not read the drive and after a few more hours of research I discovered that I need to transplant the NVRAM chip from the non working PCB onto the a working PCB.

After realizing that the PCB is the reason that the hard drive is not spinning up I also tested the Diodes on the PCB and found that the -5V Diodes could be short (the numbers where very close to 0) I removed the Diode to try to get the hard drive to work again long enough to get the data off, unfortunately this did not work. This made me come to the conclusion that I need to replace the PCB with a working one and transplant the NVRAM chip.

My Questions:
Is my reasoning/logic correct and am I on the right path to recover the data on the drive?

Once I get the new PCB for the HD is it difficult to replace the NVRAM chip and where exactly is this chip located on the board? U5 or U7? (See Pictures)

What kinda tools will I need to replace the chip and is there any tutorial on this sort of thing?

If everything goes well what programs could I use to recover my data from the drives? I've heard of R-Studio but not sure if I'm correct. I have the Lacie enclosure but I'm afraid to plug it in if it has a faulty power supply and since I didn't know much about hard drive arrays until recently I didn't label in which position each hard drive goes in and what cables plugged into which hard drive when i took them out.

I appreciate all the help and I'm sorry for the lengthy post I tried to be as detailed as I could be.

Your local TV/AV repair shop should be able to do the soldering work for you. Otherwise some board suppliers include a firmware transfer service for US$10 - $20.

As for the TVS diode(s), you appear to be unsure whether the number is singular or plural. In fact you have removed both the 5V diode and 12V. Which one(s) measured close to 0 ohms? What resistance do you measure now at the pads on the board?

What are the markings on U5 and U7?

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A backup a day keeps DR away.

I measured all TVs Diode(s) and compared them to the working PCB. I was honestly a bit confused doing this so Is a possibility that I could've it done it wrong I figured after I realized that the PCB was not spinning up the drive I would remove the -5v diode and give it a shot, after not working I lifted the -12v too and tried it again.. I don't know much about circuits or meters but the readings on the non-working PCB were a lot less than the ones on the working one. I don't have them on me so I cant give you the readings now but I do recall the -5V giving me a reading of 0L or 0.1. The -12 I do not remember.

The markings on the U5 and U7 are:

U5: S93C76
ADVH2
6889

U7: PM25LV010
AE0827
M10388C

U5 is what is referred to as "NVRAM".

As for your measurements, "OL" means that your meter has overranged on that scale, whereas "0.1" is a short circuit. "OL" is what you see when you hold the probes apart in the air (ie an open circuit), while "0.1" is what you see when you touch the probes together. These are completely different results. "OL" is good, but "0.1" is bad.

You really need to confirm your measurements.

_________________
A backup a day keeps DR away.

If your drive has burned PCB, there is a big chance that enclosure is gone also. Lacie's are very famous for enclosure failures.
Before you mess around with PCB repair and possibly making your problem worth, you should check your enclosure.

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I'll double check my measurements when I get a chance. The only reason I did this was because I felt like I had nothing to loose really and wanted to give it a shot. I figured I could always just find someone to solder the diodes back on but if the PCB board is no good regardless theres really no point. I'll just get a new PCB board and replace the NVARM chip.

Also I don't believe the enclosure is gone because it powers up (blue light is on) and when I plug in the good drive to it it spins it up with no problem, So I believe the enclosure is fine.
I'm not sure how to check if the controller on the enclosure is working correctly but I believe is the second hard drive that is the problem. It won't start up with its current PCB board.

My logic is if I manage to get a new PCB board to replace the bad one and get both drives to run I can either place them back on the enclosure and see if the computer detects it but I don;t remember how the drives where hooked up in their array so I'm a bit hesitant to do that or I can plug them both in to a PC using SATA connectors and run a data recovery program to try to bring my data back. Do you think there is a possibility this could work?

I don't know what metadata Lacie writes to your drives, if anything, but it's clear that you have a striped RAID (RAID 0).

If you connect both drives to your computer's SATA ports in JBOD mode, then you may be able to use DMDE to reconstruct your RAID.

DMDE (DM Disk Editor and Data Recovery):
http://softdm.com/download.html

Alternatively there is mdadm which runs under Linux:
http://en.wikipedia.org/wiki/Mdadm
http://linuxmanpages.com/man8/mdadm.8.php

_________________
A backup a day keeps DR away.

I would get a new pcb, swap nvram, then, once the faulty drive gets back to life i would clone them both onto two new drives, then plug the old ones to the external case and try to copy data somewhere else.
If you dont remember the disk order, just try. Eventually, it would work.
If something goes wrong, you 'd still have the clones.

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Thank you for the advice I'll let you know how it goes.