flash drive recovery

[pcpete]

We have done a couple of these in the past where the pads were tore off with good success. This time it is not working. I verified all of my connections and think everything is solid, but the drive is still dead. I have kind of giving up on it. I was more curious, do you know if these have a tvs diode like most standard hard drives do? For what it is worth I don't think this has a bad diode, but was more curious to what this part was. It seems like a tvs diode because on one side of it is ground and the other side is 5v. There is an ohm reading of 1 going through it. If it is not a tvs diode, what would it b? If you have any idea why my drive has not come back to life, I would be happy to hear that also.

 

[coffee]

For the sake of recovery, Solder your wire on the other side of the supposed diode. We really do not care about voltage reversing. Just want it to work long enough to recover data. Then throw it out. From my experience and some helpful info from others here - Its probably toast as the controller has probably failed along the way. But its worth a try since you have it this far along.

 

[pcpete]

For the sake of recovery, Solder your wire on the other side of the supposed diode.

If it is a tvs diode, that would just create a short between the 5 volt and ground and probably crash my computer. I have never seen one so small, so I was hoping to get someone to verify that

It does seem as if the controller board is bad, but what are the odds of that going bad at the same time he physically damaged it. In all honesty it seems like i did something to cause it. But, I really feel confident I did the soldering correctly

 

[pcpete]

I think I see what I need to do to fix it. i will know in the morning

 

[lcoughey]

It probably needs a chip-off recovery. Send me a line if you'd like to explore sending it my way.

 

[pcpete]

I maybe used the wrong term, when I said an ohm reading of 1, I meant that as it is an open circuit and nothing can travel through it. This would be the behavior of a tvs diode. Also, that line that looks bridged is not, I tested it, it just seems that way on the picture

here are some points of what I think are true, I did, or need to do

1. since the resistor is connected to the 5 volt pad on one side and the other side it it connected to the ground, it has to be a tvs diode. I have never seen one look just like that, but based on logic, it seems to be one

2. I soldered the 5 volt wire (wire is now removed) to the end of the diode labeled "5v #1" since it was easier than trying to connect it to the trace going to the 5 volt pad. That failed because it is only connecting to the tvs diode for overvoltage protection and is a dead end

3. I think I need to attach the 5 volt wire somewhere else. I suspect I need to attach it to the tiny contact labeled "Possible 5v needed"

 

[Krynn72]

Thats a smoothing capacitor. They'll have some voltage on one side and GND on the other. I'm like, 90% sure thats a cap. But its hard to tell from the pics where that #1 trace goes. Like, from the missing pad, where does that trace go? It wouldn't make any sense to go from the pad to a capacitor and nothing else. Unless that top #2 is also connected to the pad and going somewhere else.

 

[Larry Sabo]

It's a capacitor. Just provide 5v to "5v #1" and "Possible 5v needed" and it should work. I would try to find another point fed by "Possible 5v needed" and connect the 5v lead to it instead of the tiny stub that's left from the pad.

 

[pcpete]

Thats a smoothing capacitor. They'll have some voltage on one side and GND on the other. I'm like, 90% sure thats a cap.

So you are saying that a smoothing capacitor will bridge the 5v and ground? That is what that thing is doing. I know very little about electronics, but know a tvs diode does just that. But it does not look like a tvs diode

Edit added /
The more I think about it, it has no resemblance to a tvs diode. It must be something else. I read some capacitors do do directly to ground. They can be used to filter certain frequencies

 

[pcpete]

https://electronics.stackexchange.com/questions/52482/what-is-the-purpose-of-a-capacitor-to-ground

 

[Krynn72]

So you are saying that a smoothing capacitor will bridge the 5v and ground? That is what that thing is doing. I know very little about electronics, but know a tvs diode does just that. But it does not look like a tvs diode

Edit added /
The more I think about it, it has no resemblance to a tvs diode. It must be something else. I read some capacitors do do directly to ground. They can be used to filter certain frequencies

I'm not sure I get your terminology here with "bridging" and "going to ground" but (unless the cap is damaged) there will be no path for DC current to go to ground through a capacitor like this. A capacitor has infinite resistance, as you're seeing, so nothing will get through it unless its damaged.

I also have a relatively a basic understanding of it, but its connected to ground so that it smooths the current as the electrons "try" to get to ground through it and can't. Somehow that smooths the ripple out of the current.

Also, caps like these can often be ignored as they're "overkill" since usually the rest of the circuit can handle the ripple well enough, and its just done to be stable over the years. For data purposes you can often just remove them and the circuit still works, because again, they're not really "in" the circuit in the sense that their absence breaks the circuit. I'm NOT saying do this in your instance though! The cap is likely still working, and more importantly it hasn't been 100% determined that it even is a capacitor yet (but now I'm 99.9%).

I think @Larry Sabo has it right, and that the absence of the USB header is what is breaking the circuit between trace 1 and 2 of your image.

 

[pcpete]

Yes, we know.

Please don't take this the wrong way, but I'm getting the impression that you might be out of your depth here. If this is a client's device then you should really think about @lcoughey's suggestion of referring it to a specialist before it gets much worse.

That is the very first conversation we had. They are comfortable paying me $199 if I could recover it with the understanding a dedicated lab may charge more and I may make it worse

 

[pcpete]

I think @Larry Sabo has it right, and that the absence of the USB header is what is breaking the circuit between trace 1 and 2 of your image.

that was my thought, only that that capacitor was a diode and could probably be left off the circuit for a short time. That tiny nub is to attach it to is almost impossible and I don't see any other trace coming from it. I will see what I can do with it

 

[Larry Sabo]

That tiny nub is to attach it to is almost impossible and I don't see any other trace coming from it. I will see what I can do with it

There will be many points on the PCB that connect to the 5v rail, so I would look for a short between the 5v connection stub ("Possible 5v needed") and some of the vias nearby. When you find one that has a usable trace connected to it, connect the 5v supply to that trace. What's the make of the flash drive? If I have one, I'll find the place I'd suggest connecting to.

 

[pcpete]

There will be many points on the PCB that connect to the 5v rail, so I would look for a short between the 5v connection stub ("Possible 5v needed") and some of the vias nearby. When you find one that has a usable trace connected to it, connect the 5v supply to that trace. What's the make of the flash drive? If I have one, I'll find the place I'd suggest connecting to.

Thanks Larry. It is a SanDisk, I will get you the model later . I held one end of the ohm meter's leads on that stub and checked lots of places. I will keep looking. It is like that trace goes down and is inside the PCB. If that is the case, it must come up somewhere.

edit added
sdczstpx-002g

 

[pcpete]

I think I found a good trace. Question. When I put the two leads together I get a reading of .000 when I check this trace against the stub, I get a reading of .001. Is that little bit of resistance something to be concerned about or can i safely assume I am on the 5v trace?

 

[Larry Sabo]

@pcpete, I looked but my one Sandisks is a USB 3.0, so has a different PCB, and the other is a monolithic -- different again. I would continue looking for a via with 0.000 ohms between the stub and the via.

EDIT: I forgot to mention, if you plan to do more of these, some AWG 38 /0.1mm wire would come in handy for these, although I usually use AWG 30 wire-wrap wire for the few I have done.

 

[pcpete]

@pcpete, I looked but my one Sandisks is a USB 3.0, so has a different PCB, and the other is a monolithic -- different again. I would continue looking for a via with 0.000 ohms between the stub and the via.

thank you

 

[GTP]

is this a client's device containing their business-critical baby photos?

Hahaha! Brought tears from laughing so hard!

 

[Larry Sabo]

Something else I forgot to suggest, if you can, bridge the stub to the trace remnant attached to the capacitor, and be sure to use some flux.