Hello,
I have a V2.2 that used to work then it stared to have bad cracklings sound over the blade sounds I opened it up and…
Can someone tell me what that is and if I can repair the board? Everything seems to still work just bad sound. Also how might it have gotten blown?
Q7. FET that provides reverse polarity protection on one side, SD power uses the other.
Yes you can repair it by replacing the chip by reflowing a new one on with a hot air station.
If I had to guess, you put your battery in backwards.
Unfortunately, at the moment, this one’s not available due to the global chip shortage.
@profezzorn would need to chime in on whether or not a workaround, such as bridging the pads and bypassing its functions is even a possibility for now.
Putting the battery in backwards should not cause this.
Shorting something so that too much power passes through it could cause it though.
Bypassing it is possible, but not entirely simple.
One trick might be to rotate the chip 180 degrees, then connect SD_VDD to 3.3v.
Could work…
Now there is some wizardry! Lol. Let me see if I can find the part anywhere first, maybe someone has an old dead board I can salvage the part from. If not I might just wait till I can find a replacement part.
Thank you Mr Wizard sir.
You’d be surprised what common parts are used in random devices. I’ve been saving up boards from random stuff that I’ve already pulled parts from for other non-Proffie repairs. Last one was a chip from of all things a 3.7v powered Smoke Detector from First Alert. What’s a factory part #? I can look at what I got.
DMP2075UFDB-7
They cost 53 cents when in stock at Mouser.
datasheet:
https://www.mouser.com/datasheet/2/115/DMP2075UFDB-1274646.pdf
Thank you! 
that would be cool! Normally i would just get the part… but…
Here are some alternatives that might work:
https://www.mouser.com/Semiconductors/Discrete-Semiconductors/Transistors/MOSFET/_/N-ax1sfZ1yzvvqx?P=1yzxao2Z1z0y3dtZ1yzvc4b&FS=True
I am no electronics expert but it looks like https://www.mouser.com/datasheet/2/115/DMP2075UFDB-1274646.pdf
Is a direct replacement.
Looks like it should work to me.
Diodes Incorporated usually have lots of different chips with the same footprint, but with slightly different capabilities. I suspect they are really often the same part, just binned after they test them.
SD Card holder plastic looks oozy. Oof.
Can’t tell from the picture if the traces are damaged or not.
If the traces are fine, you should be able to clean that up and put a new chip into place.
The melty SD card holder could also be a problem though. You would have to try it and see if it still works or not.
