Hi all,

I got a dead Samsung PM871 256GB (p/n:MZYLN256HCHP-000L2), that seems to have a toasted "something"(?), as seen in the photo:



i have unsoldered the component (drive is still dead) and here is a closer look:



any ideas?

Thank you in advance!

Here are some power supply test points.

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Hello fzabkar and thank you very much for your reply!

Here are my voltage measurements (with the burned component desoldered):

pic #1:
V1: 1.27V
V2: 1.12V
V3: 0V
V4: 0.01V
V5: 1.82V
V6: 1.88V
Vboost: 12.10V

pic #2:
SATA +5V: 4.95V (all three highlighted points)
+5Vin: 4.95V (both top points)
+5Vout: 4.95V (both bottom points)

5V e-fuse:
top row points: 0V, 4.95V, 4.95V, 4.95V, 4.95V
middle row points: 0V, 0V
bottom row points: 0V, 4.95V, 4.95V, 4.95V, 4.95V

5V TVS diode:
top point: 4.95V
bottom point: 0V

pic #3:
Vin/outA: 1.82V (both highlighted points)
Vout/inA: 1.82V (both highlighted points)
Vin/outB: 1.27V (both highlighted points)
Vout/inB: 1.27V (both highlighted points)

Thank you again in advance!

Measure the resistance between ground and each of V3 and V4. If you find a short, then measure the resistances of the tiny bypass capacitors around the major ICs. That will tell you which chips are being powered from these missing rails.

_________________
A backup a day keeps DR away.

It would appear that the NAND flash is powered from 3.3V/1.8V:

https://nand.gq/#/decode?pn=K90KGY8S7C-CCK0

Therefore the NAND Vcc is missing.

_________________
A backup a day keeps DR away.

I measure resistance between:
Ground and V3: 1.09kΩ
Ground and V4: 0Ω (shorted)

and in the attached photo you can see the measured resistances of the capacitors.

How do i solve the missing NAND Vcc?

Thank you for your time

Your results are confusing. You are showing 0 ohms for the resistance across the SATA +5V supply, which is a dead short, yet your voltage measurements show that the +5V supply is present. Also, those capacitors which measure 0.02 kOhm (= 20 ohms) are the 5V bypass capacitors for the PMIC. Therefore, something is loading the 5V supply, but not enough to shut down the external PSU.

The output from V4 is shorted, so V4 = 0V. The missing output from V3 may not be an actual fault, although it's hard to know for certain. These PMICs are designed to power up each voltage rail in a preprogrammed sequence, in which case it could be that V3 is down because it is waiting for V4 to come up.

Anyway, your problem is one of the V4 capacitors, or the PMIC, or one of the NANDs. These MLCC caps do sometimes fail shorted, but in this case it would be an unlikely scenario given that the SSD was hit with an overvoltage. It's more likely that one of the semis failed, probably the PMIC.

Do you have a hot air station?

_________________
A backup a day keeps DR away.

All the resistance measurements are on the capacitors, not the resistance components.
I hope that might clear it up.


Yes, i have access to one

Could you elaborate on your thoughts ? Assuming the OP is using a standard PSU for powering the drive.

Wouldn't whatever is short be getting rather toastie?

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I would think so, too. :-?

5V into 20 ohms = 1.25W
5V into zero ohms > 1 gigawatt

That said, the OP's voltage measurements would suggest that there is no dead short. :-?

I'm inclined to suspect the PMIC. It would be a chore to desolder it, but I can't see any other way to narrow down the culprit(s).

_________________
A backup a day keeps DR away.