I acquired a second hand Pi 3B+ today but unfortunately it had a loose component on the underside of the board (3 pad component beside the SD card slot)

While trying to fix it with a soldering iron I knocked the component completely off. The pi still powers on but yields a low-voltage warning when plugged in via micro-usb (5v 2A).

I'm wondering:

How critical is it to fix this?

What is the feasibility of fixing this damage without professional help?

What component this is (in case I can source a new one to fix myself)?

one of two 3-pin components is disconnected

enter image description here

  • a professional is effectively a person with skill and possibly equipment. to diy an equivalent, you just need to acquire such. could you modify the image to indicate where the component was? all i see is what appears to be a mosfet that has been disconnected but not knocked off
    – Abel
    Feb 4, 2022 at 13:41
  • to fix the low voltage warning, try a 5V 2.5A power supply - which is the recommended specs for 3B+
    – Bravo
    Feb 5, 2022 at 0:46
  • Yes sorry, I added a second image showing the MOSFET completely removed from the board. My understanding is that it is irreparable with the tools I have available. Based on the schematic I believe it was part of the circuit that corresponds to the status led (Q5 DMG1012T)
    – Oranges
    Feb 5, 2022 at 1:14
  • I tried using the power brick from my phone which outputs 5v 4A but that still resulted in low voltage warnings
    – Oranges
    Feb 5, 2022 at 1:15

2 Answers 2


Like most of similar questions you have NOT knocked the component off; you have ripped the track off the board. It is effectively unrepairable because there is nothing left to solder to.

NOTE the proximity to PP10 suggests that this may be the MOSFET that controls the PWR LED although it may be the ACT LED), in either case its absence would have no impact on the operation of the Pi - except for LEDs (although damaged board traces may be carrying connections between other circuitry).

  • Thank you for the clarification. I suppose my only option is to continue to use the pi until it no longer works.
    – Oranges
    Feb 4, 2022 at 8:22
  1. I attached a photo of the relevant PCB section. The knocked off component seems to be a 3 leg IC. My wild guess is a transistor or regulator.

  2. The poor little guy has a marking label, Q6 or something. If there is a label, then you can find the schematic to locate and identify it.

  3. Either transistor or regulator is easy to replace. You don't need the exact equivalent, a rough spec should work.

  4. Of course you don't need an SMD, any through hole one should do.

r3b pcb 1

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