Seagate Barracuda 7200.7 Dead

[alfarom]

I've got an old (2005) IDE Barracuda 7200.7 160gb. Model ST3160021A. No sign of life at all. It has no value but I just want to practice on it to see if I can get it back to life.
Is there a tvs diode, I can remove to see if that's the problem?

I've attached a picture of the board but can't tell where the diode is. There is no obvious burnt area or any other sign of damage.

Attachments

[mr_spokk]

Check those two with a multimeter.

Attachments

[alfarom]

Not sure which is positive or negative on the diodes. Results are...

negative probe on top end of larger diode gives a reading of around .645
Opposite gives 1.99

negative probe on left of smaller diode gives 1.42
opposite gives .556

Either way they seem ok don't they?

[alfarom]

The connection points to the drive on the underside of the board are a bit discoloured. Is it worth cleaning them gently with an eraser?

[mr_spokk]

Do you measure with no power and MM on 200M ohm range?
You can clean them, no problem

[alfarom]

Yes, I did.
I'll try cleaning the connection points and see if that helps.
Any suggestions as to what else might be worth trying?

[pcimage]

Easy way to check TVS diodes is to use a MM with a “beeping” continuity mode.

If the MM beeps then the TVS is bad.

[alfarom]

Tried that as well. No beeping..

[mr_spokk]

Checked the one above as well...6.8 35v?

[alfarom]

No beep in continuity mode. Similar readings to large diode near it..

[fzabkar]

Checked the one above as well...6.8 35v?

That is a 6.8uF 35V capacitor.

[fzabkar]

Measure the voltages at the two 6-pin ICs (what are their markings?) and the F6P02 MOSFET.

The negative supply for the preamp appears to be at the rear of the PCB. Measure the voltages on the adjacent capacitors. (What are the markings on the IC?)

Tip: How to take a good PCB photo:
http://www.hddoracle.com/viewtopic.php?f=112&t=120

Tutorial - Linear and Switchmode Regulators used in HDDs:
http://www.hddoracle.com/viewtopic.php?f=59&t=231

Datasheets for HDD semiconductors, regulators, op-amps:
http://www.hddoracle.com/viewtopic.php?f=100&t=94

[alfarom]

Thanks for the help

[fzabkar]

Not sure which is positive or negative on the diodes.

The stripe is the cathode. It is also marked with a "v" on the PCB. Current flows from anode to cathode.

https://en.wikipedia.org/wiki/Diode

[alfarom]

Result... Cleaning the connection points on the pcb seems to have fixed the problem. The disk now boots up and I can access the data on it...

[mr_spokk]

Checked the one above as well...6.8 35v?

That is a 6.8uF 35V capacitor.

Yep, and it's part of the 12v power rail...

[mr_spokk]

Result... Cleaning the connection points on the pcb seems to have fixed the problem. The disk now boots up and I can access the data on it...

Nice Congrats.

[fzabkar]

Checked the one above as well...6.8 35v?

That is a 6.8uF 35V capacitor.

Yep, and it's part of the 12v power rail...

… which means it is connected in parallel with a TVS diode ...

[pcimage]

Result... Cleaning the connection points on the pcb seems to have fixed the problem. The disk now boots up and I can access the data on it...

Nice!

[fzabkar]

Result... Cleaning the connection points on the pcb seems to have fixed the problem. The disk now boots up and I can access the data on it...

I assume you mean the HDA pads. What happens if you isolate the HDA with a business card?