brushless motor esc missing component - cap?

Thread Starter

bigjoncoop

Joined Feb 1, 2019
123
hey guys

i was having a issue with one of my quadcopters and noticed one of the brushless esc Looked like it had gotten struck by the propeller... Which is a common issue. I removed it and on the bottom side I noticed that what I think is a capacitor was only attached by one side and had moved and was t. I tried to gently push it back in place to solder it back on and it fell off and is nowhere to be found... It one of the smallest sized smd... :-{

picture below

I'm positive its a capacitor but just want to make sure. It's gold with silver on both sides where it gets soldered... if so I could probably just leave it off but I think I have some of the same esc's that are bad I could take it off and replace it on this one...

thx
spedix-gs30-30a-2-4s-blheli-32-dshot-esc-3 (1).jpg
 

jpanhalt

Joined Jan 18, 2008
10,095
This may help:
1596452043138.png

If it is the capacitor on he right, the motor may not run, as that is required to drive the upper mosfets. If it is the one on the left, it is for decoupling (reducing electrical noise) and the motor may still run.

The datasheets I found were in Chinese. There might be recommended sizes there. Otherwise, the one you show appears to be larger than the others. Although that can be misleading, it may indicated a higher capacitance, say 1 uF to 10 uf.
 

Thread Starter

bigjoncoop

Joined Feb 1, 2019
123
@jpanhalt

Hey thanks for the info. And all your help in the past. I see your name come up a lot in my posts.

So since we don't know the rating of that capacitor, in case I don't have the exact ESC in my box of broken stuff, would it be safe to assume I could just replace it with any capacitor I can find off of another ESC or something else that I can solder onto that space? Or in your best guess what is the minimum rating capacitor I could put back in its place and you have any idea what size it might be if I could get one from a friend that is his assortment books
 

jpanhalt

Joined Jan 18, 2008
10,095
I would not just use any capacitor. It is an MLCC (multilayer ceramic capacitor, https://en.wikipedia.org/wiki/Ceramic_capacitor#Multi-layer_ceramic_capacitors_(MLCC)). I suspect its rating is 1 uF or more based on thickness. As mentioned, I suspect it might be 1 to 10 uf. I keep a supply of both, plus some in between.

Be sure you pick the same type (MLCC). After that, anything that is about the same thickness and size might be worth a try. Those are just guesses. If you can measure capacitance, I would definitely keep track of what I did.
 
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