Help with identifying TVS diode on HDD - used 19V plug


Would greatly appreciate any help the community can provide with the WD3200AAVS drive i managed to burn out by plugging in a 19V charger into its enclosure (it was part of a MyBook).  

I’ve read through fzabkar’s very helpful guide on TVS diodes here:  It’s given me some reassurance that maybe my data is not completely fried after all…  I’ve gone ahead and ordered a multimeter as well.

However, I’m having trouble identifying exactly which part is the TVS diode on the PCB.  Nothing looks obviously scorched/burned, and none of the numbers seem to match the “common marking codes” listed in fzabkar’s FAQ.

Could anyone help me identify which diodes/resistors I should be testing with my multimeter (when it arrives on Friday) in the below photo?  

Thanks very much to anyone who can help!




I am unable to assist you in this matter since i have never tried this. But lets see if any other user can share their experience.

Check D4 and R64.


Thanks so much!  My multimeter arrives tomorrow, I’ll give it a shot as soon as possible and report back.

fzabkar, what values should I be seeing for each of those?

D4 is definitely a short – I’m getting consistent values around 0.0-0.4 ohms

D3 is definitely not a short – i’m getting values in the hundreds to thousands of ohms?

R64 and R67 are a bit confusing – I’m getting values around 0-1 ohm for those.  Does that indicate a short or do they just have low values?  

I’m particularly confused because R64 and R67 are behaving pretty similarly, while my understanding is there’s a high change R64 shorted out but R67 should be ok?

R67 and R64 are zero-ohm resistors. Both appear to be OK.

D4 is shorted, as you say. If you remove it, all should be OK.

Best of luck.

daringwombat Did you ever get your drive working?

I too have a WD My Book 4TB WDBFJK0040HBK just boaught it last month. It has all my backup data. I was just about to mirror it and I had a student get it for me to set it up for back up . They went and plugged in a laptop 19v power suppply into my unit and now it will not power on at all.

I have read through all of the forum posts and am still not sure if I need to look at the bridge board or the drive PCB. Was wondering if the  controller board can be swapped of this exernal drive or if I have to look at replacing the shorted parts.

Previously I had a problem with a WD My Book TB Drive and I bought a controller board and swapped it and got it working just long enough to copy off the data. I also had to use HDD Regenerator software as the drive had been dropped and initially was not being read due to many bad sectors.  In any case I still have that extra PCB Board and the original from that system if needed to get spare TVS Diode or any parts

fzabkar thank you so much for your contributions to this forum. I am wondering if you could provide me some advice. I truly need the data back but do not have the $$ for data recovery. I have not opened the unit yet to determine what is blown I will do that. This newer case is alot harder to open.

You stated “However, even two identical boards will not be interchangeable.”  for WD Drives and you also mentioned that usually the blown  part could be on the drive pcb board and not the bridge board and has to be revcovered by a Specialist.

Just trying to understand where to look.

Thanks for any assistance in advance. 

@HiProfile, there are two common failure modes. The usual failure is a shorted 12V TVS diode at location D4 on the HDD PCB. The solution is to remove it. Unfortunately WD’s overvoltage protection is seriously inadequate, so there may be additional catastrophic damage. If so, then a PCB swap and firmware transfer (U12) will be required. This should cost US$50 at most.

Catastrophic failures in Western Digital PCBs:

Sometimes the USB-SATA bridge board also fails. Typically the dual MOSFET power switch will burn up. The solution is to bypass it.

Repairing Bridge PCBs in External HDDs:

If you are a good tech, or if you have a friend who is capable in this regard, then a DIY repair should be reasonably cheap. No need to part with big $$$ just yet.