Hello. I have searched these forums and google quite a bit, before I decided to register and post on here.

I have a Hitachi 2.5" 7200 7k500 500GB SATA hdd. It has worked for the last year up until recently when I put it in a new housing (last one cracked). The new housing came with the same power supply (mini- round socket to usb) as the old one. I use my externals via eSata and have had no major issues until this. While I thought all the usb power adapters would be the same, I mistakenly used the power supply from the old housing with the new housing. When I did this, I noticed the hdd was not spinning up. Tried it in the old housing - no go. Tried another hard drive in both housings (with the proper power cables) and both housings work fine.

After doing some research, I found out that most likely the polarity is reversed on the two housings power inlets (and cables). I determined that I must have fried something on the PCB. I took off the PCB, though could not visually detect any fried chips.

I went online and found a retailer that sold the exact same drives. Called them up, found one with matching model #, MLC number, and same first two lines on white sticker on PCB. Ordered it, tried it on the old drive, and the old drive now spins up, though is not recognized by pc. Then I went on to switch what I believe to be the EPROM or BIOS chip (correct me if I am calling this the wrong name) using a heat gun with a fine nozzle. The chip that I switched from old pcb to new pcb is at U6. With new board and original BIOS chip, I got no spinning again. I put the original BIOS chip back on original PCB and removed what I believe is the TVS diodes at D1 and D2. Still no spin.

Any further suggestions?

just read here:

http://www.deadharddrive.com/forums/vie ... hp?p=10442

that I have to swap both 8 pin chips the one at U6 and the one at U3 - can anyone confirm this?

Did you actually measure the resistances of D1 and D2 before you removed them?

Did you check fuse F1?

Do you have a multimeter, and could you measure the voltages at coils L1 and L2?

The chip at U6 is the NVRAM.

BTW, I'm not a DR professional, but I don't think it's looking too good for you.

_________________
A backup a day keeps DR away.

Are the pictures ORIGINAL or taken from the net as an example , and was it the DONOR or the PATIENT ?