What kind of smd fuse is this?



The part in your photo is not a fuse at all. It is an EMI filter. I am not able to tell a specific part number from the photo, but it appears to be from the EMIFIL NFE31 series from Murata. Something like NFE31PT222Z1E9L.


I hope this helped you

Well that was an example I found on the internet. I will provide a pic of the actual component on my board. However thank you very much for your response. I guess that’s why I never found it I was google searching for a fuse. Here the pic plus my pointer fingertip in the photo for size reference. Thanks again!

Ouch!!! That does not look good. Those definitely look like they are from the NFE31 series of filters, but sadly there is no way to tell which exact values are on that board. Given how bad that is fried, I am not sure if replacing them is much of an option anyway. Here are the options we have in stock anyway.


Sorry I cannot be more help on figuring out an exact part number, but I wish you luck with it. It looks like you will need it.

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Oh no… Does it look so bad that you think replacing them would not help? I have not cleaned the area yet so I don’t lose the problem spot for now. As far as checking if there good or bad, I was thinking of treating them like smd caps by removing them and measuring capacitance values while making sure they are not shorted. And for the replacement value I was going to try to check the capacitance of a good neighbor and copy the value for the bad one. What do you think about my attack plan so far? Thank you for your help Chris.

My guess is that those are filters on a set of I/O signals for the board. IME the amount of damage shown indicates extreme EMI effects from a nearby lightning strike(s).

If my guess is correct there is less than a 50/50 chance that replacing those parts will fix the circuit.

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Thanks Paul. It’s actually a hardmon kardmon logic 7 car amplifier. I believe it’s water damage from a sunroof leak. I do think they have something to do with I/0 operations because one side of the of the cap is connected to the 12v input trace on the power plug, the the other side cap is connected to 12 v trace on the board side sharing trace with 3 diode components. And the middle is connected to a ground rail. The power mosfet connected to the inductor is reading 12v on the drain, 0 v gate and .20v on source instead of 12v. After finding no ovious short I used my thermal camera and it showed those first 3 filters as the hot spot the rest of the board has temp signatures and was cold. Here a pic with more of a view off the board. The red box to the left is the inductor connected to the lowest black chip on left , the mosfet. The top 2 black chips on left are each double souses and the black chip on the right is another diode! However both sides of of filter caps both plug and diode side show 12v. So that’s weird. image|375x500