[SOLVED] Need help to identify the TVS Diode - Samsung EVO 850

Sakijura

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So I've been a major idiot and did this: http://www.hddoracle.com/viewtopic.php?f=56&t=2545
I used a Corsair PSU cable on a Seasonic Power Supply and very likely caused a short circuit on my SSD (Samsung EVO 850 500GB). This was the only peripheral connected to the "wrong" cable and caused the whole system to shut down as soon as the power cable was connected.

Did a bit of research and found this article: http://www.hddoracle.com/viewtopic.php?f=100&t=86

I've now been able to open up the SSD enclosure and want to remove the TVS Diode to hopefully recover it. However, I'm not too sure how to identify the TVS diode, so would love to have the help from an expert. I've attached a couple of images, hopefully sharp enough to determine the diode.





Any help would be greatly appreciated!
 
This SSD has an electronic fuse:

http://www.hddoracle.com/viewtopic.php?f=100&t=1615&p=8872#p8872

It appears to be pin and function compatible with an STEF4S.

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/e-fuse.jpg

Measure the resistance between ground and each of 5Vin and 5Vout. Use a screw hole as your ground reference.

If it turns out that the e-fuse is responsible for the short circuit, snip its 5Vin pins with flush cutters and retest for shorts. If the shorts go away, then add a wire link between the 5Vin and 5Vout test points, or flow a blob of solder between them.
 
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Sakijura

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That article refers to an HDD, not SSD.

But, the author is usually around here.
Paging @fzabkar
Thanks for your reply and tagging the author.

It might make a difference, though I believe I'm having the same issues as described in the article. I'd expect it to be extended to SSD's as well (not just HDD's), though I could be wrong of course.
 
This SSD has an electronic fuse:

http://www.hddoracle.com/viewtopic.php?f=100&t=1615&p=8872#p8872

It appears to be pin and function compatible with an STEF4S.

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/e-fuse.jpg

Measure the resistance between ground and each of 5Vin and 5Vout. Use a screw hole as your ground reference.

If it turns out that the e-fuse is responsible for the short circuit, snip its 5Vin pins with flush cutters and retest for shorts. If the shorts go away, then add a wire link between the 5Vin and 5Vout test points, or flow a blob of solder between them.
 
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Sakijura

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This SSD has an electronic fuse:

http://www.hddoracle.com/viewtopic.php?f=100&t=1615&p=8872#p8872

It appears to be pin and function compatible with an STEF4S.

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/e-fuse.jpg

Measure the resistance between ground and each of 5Vin and 5Vout. Use a screw hole as your ground reference.

If it turns out that the e-fuse is responsible for the short circuit, snip its 5Vin pins with flush cutters and retest for shorts. If the shorts go away, then add a wire link between the 5Vin and 5Vout test points, or flow a blob of solder between them.
Thank you for your reply. :)

Makes sense! I was already losing my mind thinking I'm unable to identify a diode. Seem like it's got an e-fuse instead.

I'll need to get the appropriate tools before I can run the test. This should also be done with a digital multimeter, correct?

And excuse me for asking but how do I use a screw hole as ground reference // what does that mean exactly?
 
A digital multimeter can cost as little as $5. You don't need a Fluke for this task.

When I say to use the screw hole as your ground reference, I mean to connect the black probe (COM-mon terminal) to it. The red probe goes to each of the 5V test points.
 
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Sakijura

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A digital multimeter can cost as little as $5. You don't need a Fluke for this task.

When I say to use the screw hole as your ground reference, I mean to connect the black probe (COM-mon terminal) to it. Th red probe goes to each of the 5V test points.
Excellent, thank you for the clarity. I've ordered a simple multimeter and will hopefully be able to test it tomorrow. Thanks for your help so far, much appreciated!
 

Sakijura

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This SSD has an electronic fuse:

http://www.hddoracle.com/viewtopic.php?f=100&t=1615&p=8872#p8872

It appears to be pin and function compatible with an STEF4S.

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/e-fuse.jpg

Measure the resistance between ground and each of 5Vin and 5Vout. Use a screw hole as your ground reference.

If it turns out that the e-fuse is responsible for the short circuit, snip its 5Vin pins with flush cutters and retest for shorts. If the shorts go away, then add a wire link between the 5Vin and 5Vout test points, or flow a blob of solder between them.
I've now been able to measure the resistance on each of the 5V in and 5V out pins.
At first it was showing a clear 1 on all pins, but when I increasted the Ohm setting to 2M, I was seeing about .550~.600 for the 5V ins and about 1.350~1.450 for the 5V out pins (using the inside of a screw hole as ground).

If you don't mind explaining... What does that mean? And how do I determine whether the e-fuse is causing the short?
 

Sakijura

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There are no shorts. In fact the e-fuse looks OK.

Can you confirm that there is no short between the +5V and Ground pins in the SATA power connector?

https://pinoutguide.com/Power/sata-power_pinout.shtml
I'm not sure how to determine a short, but these are the values I got using the same resistance measuring methods as before:
I noticed that the longer I hold the red probe onto the 5V pins, the higher the resistance becomes. (this also applies to the e-fuse in and out pins previously measured)
*Edit: Another thing I noticed is that the +3.3V and the +12V pins offer a resistance of 1. Whenever I test their resistance, nothing happens, the counter stays on 1. Could it be that the problem is with the 12V ones, not the 5V?

4GNDGround = Starts at 0.02 M Ohm and then goes to 0.00 after a couple of seconds
5GNDGround = Starts at 0.02 M Ohm and then goes to 0.00 after a couple of seconds
6GNDGround = Starts at 0.04 M Ohm and then goes to 0.00 after a couple of seconds
7+5VDC5 V Power, Pre-charge = 0.2M Ohm
8+5VDC5 V Power = 0.2M Ohm
9+5VDC5 V Power = 0.25M Ohm
10GNDGround = Starts at 0.02 M Ohm and then goes to 0.00 after a couple of seconds
11OptionalStaggered spinup/activity = Fluctuates between 0.2 ~ 0.9M Ohm
12GNDGround = Starts at 0.02 M Ohm and then goes to 0.00 after a couple of seconds
 
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Sakijura

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There are no shorts, so I can't understand why your SSD shuts down your PSU, unless you are still using the wrong cable.
When I connect the SSD to a PSU using the correct cable, the system will not shut down, however the SSD won't initialize and thus will not be detected. I've also tried connecting it directly to a USB port with a USB 3.0 to SS Micro-B cable, also nothing.

When I connect the SSD to a PSU using the wrong cable, the whole system shuts instantly (it will run fine as long a this cable is not connected).

I can't see any reason why the SSD would not boot other than a short circuit. At what point would it be safe to say it's defective?
 
Start by measuring the voltages between ground and each of 5Vin and 5Vout.

If these are OK, then measure the voltages at the onboard power supplies.

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/regs1.jpg
http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/regs2.jpg

These appear to be the "safe mode" shorting points (determined by reference to other Samsung SSDs, Evo 840):

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/Safe_Mode_JTAG.jpg

If you short the two safe mode pads with tweezers before and during power-on, and then release them, the SSD should start in safe mode. This is the mode in which it prepares itself for a firmware upload. If you can see something in BIOS at this time, then this will prove that the flash controller has basic sanity.

There are two pins in the SATA power connector that are connected to the flash controller. These are DevSleep/PWRDIS (pin #3) and Staggered spinup/activity (pin #11). I would think that if a bad voltage was applied to these pins, then the controller may have been damaged.
 

Sakijura

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Start by measuring the voltages between ground and each of 5Vin and 5Vout.

If these are OK, then measure the voltages at the onboard power supplies.

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/regs1.jpg
http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/regs2.jpg

These appear to be the "safe mode" shorting points (determined by reference to other Samsung SSDs, Evo 840):

http://www.users.on.net/~fzabkar/SSD/Samsung/Evo-850/Safe_Mode_JTAG.jpg

If you short the two safe mode pads with tweezers before and during power-on, and then release them, the SSD should start in safe mode. This is the mode in which it prepares itself for a firmware upload. If you can see something in BIOS at this time, then this will prove that the flash controller has basic sanity.

There are two pins in the SATA power connector that are connected to the flash controller. These are DevSleep/PWRDIS (pin #3) and Staggered spinup/activity (pin #11). I would think that if a bad voltage was applied to these pins, then the controller may have been damaged.
Happy New Year Fzabkar! :)

Thanks for getting back on this.
I'm not a 100% certain if I'm doing it correctly, but when I keep the black probe on a screwhole as ground and place the red probe on the 5V in and 5V out pins (while measuring the voltage, using the V~ 200V setting), the voltage remains at 0.00, sometimes showing a - (minus) symbol in front of it. Is that supposed to be the case or should I be seeing a different number on those in and out pins?

(The same applies to the onboard power supplies as you've indicated on the screenshots.)

Was I supposed to connect the card to power first?
 

Sakijura

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Yes. No power, no voltage.

Be very careful not to slip with your probes, otherwise damage may result.
Makes sense. First time I'm trying such a thing. Here are my findings so far:

V5 in: Both measured at 10.1 V
V5 out: Both measured at 04.0 V

As indicated on the screenshots for the onboard power supplies:
V1 = 0.00
V2 = 0.00
V3 = 0.00
V4 = 0.00
V5 = 0.00
V6 = 0.00
V7 = 0.00
V8 = 03.4 V

I could only find a non-zero measurement on the V8 one. Something tells me that shouldn't be happening, but tbh not sure what that means.

I have not tried running this in safemode yet but I will try that now and see what the result is.
 

Sakijura

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5Vin should be +5V. Something is very wrong here.

Find a 1.5V or 9V alkaline battery and measure its voltage. If you get the wrong result, then your meter may have a flat battery.
I've now also tried shorting it by conneting the safe mode points holes with tweezers, that didn't offer anything unfortunately, it was not detected and I couldn't hear the SSD "boot".

Just tested the meter on 2 different 1.5V batteries. One was showing 1.565, one was showing 0.986. They may have previously been used though.
I'd find it hard to imagine the multimeter has a flat battery, I had purchased it new just 2 days ago.

The readings on the 5V in points seems to be accurate, I've tried it a couple times but consistently comes to the 9 ~ 10 range. Is there anything else I can troubleshoot from here?
 
If you really are seeing 10V between SATA +5V and Ground, then your cable is wrong.

Disconnect the cable from your SSD and measure the voltages at each of its 15 pins. You can use the metal case of your PSU as the ground reference.
 

Sakijura

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If you really are seeing 10V between SATA +5V and Ground, then your cable is wrong.

Disconnect the cable from your SSD and measure the voltages at each of its 15 pins. You can use the metal case of your PSU as the ground reference.
Sorry I thought you were referring to the 5V in and 5V out pins near the e-fuse.
Sounds like you are referring to the SATA power connector pins instead.

Would you mind clarifying which +5V pins I should be measuring by circling them on the screenshot?

Apologies for being such a pain, completely new to this and genuinely appreciate your help.
 

Sakijura

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I was referring the 5V in/out pads on the SSD. The 5Vin pad is connected to the SATA +5V pins at the connector. If you have 10V at the connector, then you will have 10V at the 5Vin pad ...
Okay, measured the voltages from each pin, coming from the SATA power cable connected to the power supply:

1 = 06.4V
2 = 06.4V
3 = 06.4V
4 = 0
5 = 0
6 = 0
7 = 10.1
8 = 10.1
9 = 10.1
10 = 0
11 = 0
12 = 0
13 = 25
14 = 25
15 = 25

Shall I test the same thing using a different power supply and different SATA Power cable?
 
Those voltages are twice the value they should be. This is symptomatic of a flat battery in your meter. The meter should have a "low bat" warning of some kind.

I now believe that the actual values of 5Vin and 5Vout are 5V and 2V, respectively. This would suggest that the e-fuse has died while protecting your data.
 

Sakijura

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Those voltages are twice the value they should be. This is symptomatic of a flat battery in your meter. The meter should have a "low bat" warning of some kind.

I now believe that the actual values of 5Vin and 5Vout are 5V and 2V, respectively. This would suggest that the e-fuse has died while protecting your data.
Possibly... This is what I get when I use the power supply tester:


If the e-fuse died, what can I do to recover the data?
 
If I were able to trust your measurements, I would suggest that you use your tweezers to connect one of the 5Vin pads to one of the 5Vout pads. This would bypass the fuse. If you then see your SSD in BIOS, I would power down the SSD and get someone to solder a link between the two pads.

Of course there are risks, but if there are further problems downstream from the fuse, then I think your DIY adventure will be over in any case.

BTW, your meter will probably have a 9V battery. Maybe you could borrow one from a smoke alarm?
 

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