TVS diode location

[abolibibelot]

@lcoughey

I just finished a case with a Toshiba 2.5" drive with a blown fuse. Had they just got the board repaired, they would have left with a crashing hard drive that would have likely resulted in them losing all their data.

Could you elaborate a bit on this ? What would have happened following a board repair attempt ? Isn't there a way to attempt a repair of the board, then test it without the actual drive, and then connect the whole drive if the repair was a success ? How does a data recovery specialist know that there's, for instance, an issue with the preamp, without plugging the drive ?

[littlemoule]

i'm feeling the same. He hasn't really described the details on what actually happened. Without the board, there is no way to test the pre-amp is my understanding.

[fzabkar]

Without the board, there is no way to test the pre-amp is my understanding.

I'm cynical. I've been watching this forum for 10 years and in that time I could count on the fingers of one hand the number of people who could identify appropriate test points. In this case one would locate the power supply voltage(s) for the preamp and test the resistance to ground. A blown preamp will often show a short circuit to ground at its supply rail(s).

A possibly better approach, at least for those preamps that identify themselves via terminal, would be to mask off the VCM pins, thereby preventing the heads from moving off the ramp. But then you would need to find someone who understands how to identify the VCM pins …

[littlemoule]

I'm cynical. I've been watching this forum for 10 years and in that time I could count on the fingers of one hand the number of people who could identify appropriate test points. In this case one would locate the power supply voltage(s) for the preamp and test the resistance to ground. A blown preamp will often show a short circuit to ground at its supply rail(s).

A possibly better approach, at least for those preamps that identify themselves via terminal, would be to mask off the VCM pins, thereby preventing the heads from moving off the ramp. But then you would need to find someone who understands how to identify the VCM pins …

lol, I only understood 5% of that. It's amazing how knowledgeable some people in this forum are. By the way, I saw your original writeup about tvs diodes, very well done.

I am still waiting for my circuit board to arrive, I realized it's coming from Ukraine not Israel. So let's see.

[lcoughey]

What I was saying is that while the board was toast, there was also significant media damage on the surface of the drive. Almost 100% of the DIY cases I see with blown PCBs, they almost always assume that if the drive IDs and reads, it is healthy and safe to continue to use. A data recovery professional will (should) always get a clone of the drive the very first time it is detected. The odds are, the media damage was completely unrelated to the damaged PCB.

If you think that fixing/replacing the PCB is all that needs to be done, you are mistaken. A clone of a healthy drive means that the data is backed up. A crashed repaired drive, is irreversible.

[littlemoule]

this actually makes no sense. The drive in question is a hitachi ultrastar, was well taken care of. never dropped. Media damage would happen exactly how? It seems like the drive you repair was handled by a turd who "did other things to it" and media was damaged. This is called causal effect, it is not a rule.

But we will see when the PCB arrives, assuming no damage happened to the pre-amp. I am 100% sure the 'media' is intact.

The fact that your location says Ontario Canada and you obvious represent a data recovery company as shown via your profile picture leads me to conclude that you are trying to pull off a 'scare sell' tactic. It's a classical marketing approach. Mods do need to clean this up. This drive is never coming to you buddy even if the data is done for.

[lcoughey]

this actually makes no sense. The drive in question is a hitachi ultrastar, was well taken care of. never dropped. Media damage would happen exactly how? It seems like the drive you repair was handled by a turd who "did other things to it" and media was damaged. This is called causal effect, it is not a rule.

But we will see when the PCB arrives, assuming no damage happened to the pre-amp. I am 100% sure the 'media' is intact.

The fact that your location says Ontario Canada and you obvious represent a data recovery company as shown via your profile picture leads me to conclude that you are trying to pull off a 'scare sell' tactic. It's a classical marketing approach. Mods do need to clean this up. This drive is never coming to you buddy even if the data is done for.

I'm not interested in your work. You are seeking advice and this thread was only focusing on half a job. I gave a recent real-life example to make my point. If you choose not to follow my advice and clone the drive or back up the data immediately after you change the PCB, that is your choice. I just think it is shameful for advice to be given on a data recovery forum that puts data at risk.

Yes, I could change to an anonymous profile and not mention my lab in my signature. But, I'd like to think that it gives my advice some credibility.

If there is anything that one learns very quickly with data recovery is to always assume the worse and hope for the best.

[HaQue]

I am wondering what "was well taken care of." actually means?

did you wipe it down, say nice things to it, change the oil at exactly 150,000hrs?

Media Damage could mean over time some particles dislodge from somewhere and start circulating, causing damage.

Things go bad all the time to "perfectly good" devices. Maybe there is more you don't understand 5% of.

BTW, having HDD Pros on a HDD forum is actually a GOOD thing...

[pepe]

Media damage would happen exactly how?

Sorry, i had to smile on that
The same way millions of hard drives die peacefully in computers that weren't abused.
To put it in another way, they just die sometimes, sooner or later, for no obvious reason, at least none that one could call mishandling.


pepe

[fzabkar]

AIUI, server drives often fail with media damage. I would think that server environments are about the best that a drive will see, yet they still fail.