Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

[Ralphie]

For a while now I have an old Samsung S4 Mini (GT-I9195) lying around. It doesn't boot at all, gives no response whatsoever. It has some data on it still that may be useful to me however (I don't really know, maybe some old photos). Anyway, mostly for the fun of it I want to try to get the data.

Now I'm not particularly skilled at working electronics, so actually fixing the device is something that probably will be quite difficult (if I want to do this myself). I don't even know where the problem is on the motherboard. It's probably some kind of chip that is broken, or a short on the motherboard. And repairing the old device is not worth it anyway, although I might try that later.

Anyway, lacking the necessary skills, I think my best option is to just transfer the EMMC chip to a replacement motherboard. For the GT-I9195 they run quite cheap (although they are probably used but who cares as long as it works). So for that I need to remove the EMMCs from both the old and the new board and swap them. My question is if I can just reflow the old chip on the new board. Or do I need reballing? I've never done this, so not sure if a reflow is possible when you put the chip on a different board.

A second option is, since I don't need the device working anymore anyway, to get the data from the flash chip directly. It's possible to get a new chip to practice with even: this one is the exact same SDIN7DU2 chip (datasheet) with a BGA153 interface. Since it's just an EMMC chip I should be able to connect it to a USB SD card reader. Or even simpler, I can use a simple USB drive with a BGA153 pad like this one. Even easier is a hot-swap reader, like this one, but it's quite expensive (no idea why such a thing (essentially an LGA socket for a BGA153 chip) should be so expensive; I guess a low turnover).

As a third option, this guy here did something even more impressive: He just looked at the schematics and simply connected wires to hook up to the chip to his computer while still on the motherboard. However, I cannot find any schematics. (Does anyone have them for the GT-I9195?) I've even seen people solder tiny wires to the EMMC, but that is far beyond my capability I think (and I don't have the tools).

So I think I'm gonna go ahead with option 1 and buy a replacement motherboard and transfer the chip. I wonder if people agree that's the way to go under these circumstances? I'd be grateful for any comments or guidance from experts. And some help along the way would be great as well.

[Ralphie]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Anyone?

[elecsoluces]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Hello,

Generaly the EMMC is paired to the CPU and other components so I don't think you can swap only the EMMC. For sure you need to reball the chip if you want to solder back properly, it's not easy if you're not familiar with this process.
the most simple in this case is to connect the motherboard to a JTAG interface like easy jtag plus or EMMC pro, no need to remove the EMMC you have to connect 6 wires to the motherboard.

[Ralphie]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Hello,

Generaly the EMMC is paired to the CPU and other components so I don't think you can swap only the EMMC. For sure you need to reball the chip if you want to solder back properly, it's not easy if you're not familiar with this process.
the most simple in this case is to connect the motherboard to a JTAG interface like easy jtag plus or EMMC pro, no need to remove the EMMC you have to connect 6 wires to the motherboard.

Thanks for your reply. What do you mean with the CPU being paired to the CPU? You mean in software? I'm sure that's the case in new phone models, but this one is quite old. In fact, in this Turkish movie they just replace the eMMC for the S4 mini, because some board diagnostic shows it to be faulty.

They use super professional tools to do it in that film so I guess they know what they're doing. Does anyone know what kind of thing they plug into the USB port in that Youtube video? I don't speak Turkish so I cannot tell.

I know it's a difficult task to take out the eMMC chip and then solder it onto a new board. But it would be cool if I can actually repair the phone completely and actually boot from the eMMC. So I'd like to try that.

The JTAG interface also sounds interesting. I don't know how to access the phone via JTAG though. I have no schematics.

What you mean with "soldering six wires to the motherboard", that is akin to this, right? No actual need for JTAG there, is there? Or do you mean that JTAG is accessible with those six wires? Does JTAG allow for data recovery?

Interestingly, here is another old thread about the same device.

I hope you or someone else can answer some of my questions!

[Ralphie]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Does anyone at least know if it is possible to "repair" the whole phone by just swapping the eMMC to a working motherboard?

I understand that in recent phones components may be paired to each other (so as to prevent this kind of tampering and inability to repair yourself). But wouldn't it just work after a successful reball for such a relatively old device?

[mon2]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Yes, I believe it can work provided the data is not encrypted.

Check out the assorted videos on this topic from REWA such as this one:

https://www.facebook.com/rewatechnol...0234426416663/

Also ipad Rehab (Jessa) has many on this subject as well:

https://www.bing.com/videos/search?q...tail&FORM=VIRE

[reformatt]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

It depends on what Android version is on it. In the early days you could just take the eMMC off the board and throw it on a reader. This was until Android 6 (if I recall correctly), where data encryption was enabled by default. So yes you could read it, but the data is encrypted. The encryption key is unique to the phone, and changes between resets. If this is the case, you have to repair the board and get it to boot to get the data.

If its not encrypted, you can take the eMMC off the boad and try to read it with a SD card reader. You can use the Transcend TS-RDF5K (this is the one recommended by hackers as it supports one wire mode) and some eMMC to SD card adaptors.

https://shop.exploitee.rs/

If you don't want to get the adaptors, you can do what's called the dead bug method. Flip the chip on it's back and solder wires directly from the chip to the pins on the SD card reader.

This can also be done in circuit, however you will likely need to have a boardview to work out where to access the pins. eMMC usually can run either 1.8V or 3.3V logic too so it's easier to take it off the board.

[Ralphie]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Yes, I believe it can work provided the data is not encrypted.

Check out the assorted videos on this topic from REWA such as this one:

https://www.facebook.com/rewatechnol...0234426416663/

Also ipad Rehab (Jessa) has many on this subject as well:

https://www.bing.com/videos/search?q...tail&FORM=VIRE

Thanks, those are cool videos and fund to watch . It's totally incredible what people can do with a seemingly unrecoverable mess!

I thought about encryption, but this is an old device so I don't think it's encrypted. If anyone knows of a way to know for sure, let me know.

[Ralphie]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

It depends on what Android version is on it. In the early days you could just take the eMMC off the board and throw it on a reader. This was until Android 6 (if I recall correctly), where data encryption was enabled by default. So yes you could read it, but the data is encrypted. The encryption key is unique to the phone, and changes between resets. If this is the case, you have to repair the board and get it to boot to get the data.

That is indeed one possibility. A bonus however would be if I could actually boot it up and run the OS. So I'd like to go for that first. Since it came out with Android 4, I don't think this is encrypted. However, I put Android 10 on it by the work done in this thread: https://forum.xda-developers.com/t/r...-mini.4045147/

If its not encrypted, you can take the eMMC off the boad and try to read it with a SD card reader. You can use the Transcend TS-RDF5K (this is the one recommended by hackers as it supports one wire mode) and some eMMC to SD card adaptors.

https://shop.exploitee.rs/

If you don't want to get the adaptors, you can do what's called the dead bug method. Flip the chip on it's back and solder wires directly from the chip to the pins on the SD card reader.

To your knowledge, what would be easier: this dead bug method or swapping the eMMC over to a new board by reballing? (Reflowing is not possible according to @elecsoluces, though I would like to hear what others think as well!)

This can also be done in circuit, however you will likely need to have a boardview to work out where to access the pins. eMMC usually can run either 1.8V or 3.3V logic too so it's easier to take it off the board.

Indeed, the guy in the Youtube film I linked noticed the same about the voltage. But I have no schematics, so doing this in circuit is no option for me. Also, in a phone everything is even smaller than in a laptop, so without a good microscope I can hardly hope to solder anything!


In any case, I think I will go for reballing then. To do this, I think I will get balls and a stencil and just try to do it as the example in the videos show. Any pointers of course appreciated!

[reformatt]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Well if you updated to Android 10, then it's very likely encrypted. You'll have to repair the board in order to get your data in that case.

Data recovery on phones these days always relies on either repairing the boards, or transferring the IC's that tie the encryption together across to a donor board. Lot of effort if you don't know exactly what data you're after.

I'm assuming you're certain it's a board issue though? Older Samsung phones use rigid OLED displays, and usually fail completely with any kind of drop (even when they don't look damaged). Rule out the screen, then charge port, battery etc, then proceed to do basic troubleshooting on the board.

[Ralphie]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Well if you updated to Android 10, then it's very likely encrypted. You'll have to repair the board in order to get your data in that case.

Data recovery on phones these days always relies on either repairing the boards, or transferring the IC's that tie the encryption together across to a donor board. Lot of effort if you don't know exactly what data you're after.

I'm assuming you're certain it's a board issue though? Older Samsung phones use rigid OLED displays, and usually fail completely with any kind of drop (even when they don't look damaged). Rule out the screen, then charge port, battery etc, then proceed to do basic troubleshooting on the board.

Thanks for these pointers.

So I actually have a second, identical Samsung S4 Mini, which is working fine. It does not have the exact same ROM on it (from the mentioned thread) but one of the published versions there. The phone is not encypted: it says so in Android settings! So that very likely means that the faulty phone is unencrypted as well.

As for the ruling out if it's a board issue: good to verify indeed! With two phones that's easy: I put the board in the other phone and indeed it does not work. To be sure I actually swapped the boards between the phones. Now the working phone's board is humming along in the previously not working phone and the faulty board is in the previously working phone.

Also, from some more example repair videos I watched, I suspect that the power IC is faulty, but only because in the past I remember that the phone didn't charge properly anymore as well (it didn't charge all the time). But I don't know how to check.

But like I said, without some more knowledge I don't really know how to troubleshoot the problem. So I thought swapping the flash would be easiest.

BTW you mention the USB charge port, but that is on a separate board on this phone and it should boot without being connected (it does on the other phone).

[reformatt]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Ok, a donor phone is very handy. So common things on phones are going to be shorted caps near the edges (from liquid damage) so just run around them with a meter. But yes, damaged PMIC was a thing on the older Samsung phones. You might fare better over on the mobile repair forum on Reddit. Some clever guys on that sub like arcaine2.

[Ralphie]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

Ok, a donor phone is very handy. So common things on phones are going to be shorted caps near the edges (from liquid damage) so just run around them with a meter. But yes, damaged PMIC was a thing on the older Samsung phones. You might fare better over on the mobile repair forum on Reddit. Some clever guys on that sub like arcaine2.

Ah, "PMIC" is the proper acronym indeed. Good to know that older Samsung ones are susceptible to this. And I guess because the board does not boot both from sticking in a USB cable, nor using the power button is a possible indication that the PMIC may be defective, no?

So yeah I'm willing to put some more effort into actually diagnosing the problem. Although for something like micro-soldering I have nor the skills nor the equipment, so to do that myself would be a long path to success I think.

That said, if I can establish with relative certainty that the PMIC is defective then I might as well swap that IC from the donor phone. At least it has less pins than the EMMC, so should be easier!

The PMIC is this one. It's referred to by Samsung as U501. Although strangely, on the chip itself is written neither of these: https://youtu.be/jiKyTiorFbU?t=432 (Spanish video where they replace it). Here some person posted some diagnostic guide: https://www.badcaps.net/forum/showthread.php?t=101343. The first flowchart for the phone not starting might point to replace both U500 and OSC500. The latter seems to be the same chip as the U501/PM9817, which makes sense to replace if the board does not start. (Weird though that the PM9817 would be referred to by both U501 and OSC500, or isn't it?)

But for those things it might indeed be a good tip to go to a place where people have more expert knowledge about phones. Thanks for the referral to Reddit. I'll see if I can present my problem there as well. Who knows they might come up with something else entirely. In any case it's quite interesting to see in the beginning stages of such a project how many possibilities there are of going about achieving the goal.

[reformatt]

Re: Data recovery on an old Samsung S4 Mini - Teach me some interesting electronics!

The PMIC is a BGA IC and will have lead free balls on it. They aren't underfilled, so thats a bonus. But some practice is needed if you aren't experienced. Maybe try this on a few donor boards first (spare boards for this model are very cheap so maybe experiment on those first if your data is important). You could end up pulling pads during removal, or cleaning up the pads of lead free solder. And you need good flux too, not that fake Amtech crap off Aliexpress. I'm currently using Interflux no clean and this is excellent. (Amtech 559 is hard to get outside of the US and whats out there is usually fake).

Buy a chip pre-balled is easier, otherwise you'll need stencils and balls/solder paste if you plan to swap IC's.

Look up u/arcaine2 on Reddit, he has the best knowledge I've seen on that sub for Android phones and data recovery. I got out phone repair a while back as it's just too much hassle now.