The "4r7" box on the mainboard of this Pi Zero W is cracked and the insides are exposed. It seems to be working fine.

enter image description here

My questions are:

  • What is this?
  • Is it ok that it's exposed?
  • Is there something I can do to protect it (a drop or 2 of hot glue perhaps?)

Thank you!


This is an inductor, which is part of the voltage regulator circuitry.

The picture shows evidence of overheating, as does the adjacent chip (which is the regulator).

Anything you are going to do (glue or whatever) is only going to make any issue WORSE. The inductor would have been made with insulated wire; it it were overheated to such an extent that the insulation is damaged, it will be internal. Glue will only make it worse.

I would be more concerned at WHY it was overloaded (my guess would be excessive current from 3.3V).

  • Hi, thanks, what evidence do you see that indicates overheating? The 4r7 box was actually cracked (shattered really) when I got it from adafruit. It was all there, but it was cracked in every direction. I think the slightest touch from a wire or one of those rubber bands is what made it finally fall apart. I definitely should have requested a new one, but I had a project (at the time) that was time-critical so I went ahead with it. I'm curious what else indicates a heating issue though. Thanks for the info! – Adam Plocher Sep 19 '17 at 1:07
  • Btw the shiny stuff at the top is hot glue (from the camera ribbon which 100% of the time comes out without a little glue from my experience). – Adam Plocher Sep 19 '17 at 1:12
  • Is there any sort of fire risk or anything with it being exposed the way it is? I mean am I putting my families safety at risk by using this as a security cam? :) Thanks again. – Adam Plocher Sep 19 '17 at 1:15
  • It is difficult to judge from a photo, it looks to me like overheating, from whatever cause. The risk of fire is minimal. None of the components should ever get over 60-70 ℃ in normal use. – Milliways Sep 19 '17 at 1:35

The component in the top left of your photo is an inductor.

The black bit on the top that is cracked is just plastic and not vital to the operation of the component.

A drop of hot glue or some sort of non-conductive laquer should prevent any short-circuit to the exposed copper.

Hope this helps!

  • Thanks Jordan, I guess there's two concerns. One is the possibility of shorting it, and the other relates to the temperature. It sounds like (from Milliways post) that it needs to be able to "breath" so I guess I'll leave it as is for now... – Adam Plocher Sep 19 '17 at 1:14
  • No worries, personally I see no evidence of overheating. If there was, the glue you already have nearby would've melted. – Jordan Croft Sep 19 '17 at 8:22

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