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!
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| SSD Samsung PM871 256GB http://forum.hddguru.com/viewtopic.php?f=10&t=42922 |
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| Author: | gadragon [ December 7th, 2022, 5:45 ] |
| Post subject: | SSD Samsung PM871 256GB |
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! |
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| Author: | fzabkar [ December 7th, 2022, 13:48 ] | ||||
| Post subject: | Re: SSD Samsung PM871 256GB | ||||
Here are some power supply test points.
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| Author: | gadragon [ December 8th, 2022, 5:39 ] |
| Post subject: | Re: SSD Samsung PM871 256GB |
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! |
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| Author: | fzabkar [ December 8th, 2022, 12:15 ] |
| Post subject: | Re: SSD Samsung PM871 256GB |
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. |
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| Author: | fzabkar [ December 8th, 2022, 13:07 ] |
| Post subject: | Re: SSD Samsung PM871 256GB |
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. |
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| Author: | gadragon [ December 9th, 2022, 7:22 ] | ||
| Post subject: | Re: SSD Samsung PM871 256GB | ||
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 
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| Author: | fzabkar [ December 9th, 2022, 13:18 ] |
| Post subject: | Re: SSD Samsung PM871 256GB |
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? |
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| Author: | gadragon [ December 9th, 2022, 13:35 ] |
| Post subject: | Re: SSD Samsung PM871 256GB |
fzabkar wrote: You are showing 0 ohms for the resistance across the SATA +5V supply All the resistance measurements are on the capacitors, not the resistance components. I hope that might clear it up. fzabkar wrote: Do you have a hot air station? Yes, i have access to one |
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| Author: | Lardman [ December 9th, 2022, 13:57 ] |
| Post subject: | Re: SSD Samsung PM871 256GB |
fzabkar wrote: Therefore, something is loading the 5V supply, but not enough to shut down the external PSU. 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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| Author: | fzabkar [ December 9th, 2022, 14:44 ] |
| Post subject: | Re: SSD Samsung PM871 256GB |
Lardman wrote: fzabkar wrote: Therefore, something is loading the 5V supply, but not enough to shut down the external PSU. 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? I would think so, too. :-?
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). |
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