WD SN850P parts

Hello all, new to posting here but i was hoping someone could point me in the directions of possible parts namely I think resistors or onboard fuses. I obtained an SN850P used from someone on facebook who said it had 0 problems, turns out it wont read in my ps5 nor my pc and upon closer inspection there was a small burn mark where a resistor or fuse was meant to be see pic can anyone please help point me in the direction needed to source this part? Thank you for listening to my rambling

That looks like a TVS diode. It protects the drive from overvoltages. This component can be removed without affecting the functionality of the SSD. In short, there is some other problem.

Ah ok I see. On mine that diode is completely gone and just has the 2 solder points on the board left after it burned off… if that diode is gone then it would still function?

If the diode was desoldered due to heat from an overvoltage, then you can expect more damage downstream. I would be looking around the “1D” MOSFET (U4, top) and PMIC chip (U6, “HORUS”) in the centre of the PCB. They would be the next in line.


BTW, it’s not unusual for bits to fall off WD’s and SanDisk’s SSDs:


Alright I hugely appreciate the knowledge share, im still relatively new to circuit boards and such, do I ohm test the ones you listed to check? Thank you

Measure the voltage at the TVS diode. Also measure the voltages at the drain and source pins of U4. These should all be +3.3V.

Also measure the voltages at each of the 4 inductors surrounding the HORUS IC. The inductors are the larger rectangular components. Each has 2 smaller capacitors adjacent to it. Measure the voltages at the capacitor end of each inductor.

Use the mounting screw cutout, or the top end of the TVS diode, as your ground reference.

PMPB20XPE, NXP, -20V, -10.3A, P-channel Trench MOSFET, marking 1D, DFN2020MD-6 (SOT1220):

Thank you very much for trying to help me sir, unfortunately in my haste I accidently broke the board. Ah well a lesson in patience on my behalf but I wanted to show my appreciation for your help. From now on Im going to make sure a drive works before buying it… someones word unfortunately doesnt go as far with some people. Anyway thank you again for trying to help