I bought a non-working F1 Kontrol for cheap. After inspecting the Voltage and GND, I found that they were shorted, but since I removed the USB-B port the short between GND and VBUS persisted.
My next move was to remove the VBUS Protection Diode. It’s a surface-mount protection diode (TVS/Zener) immediately next to the positive 5V track coming from the USB terminal pads to suppress spikes.
It is the small, black rectangular two-terminal component which is removed (seen on the white background). I’ve measured with a multimeter to its two pads. It was beeping so I desoldered it completely. I’ve checked the main VBUS-to-GND pads once again. The beep stopped, so the diode is indeed dead and needs replacement.
So, I now have a couple of questions.
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Does anybody know what kind of diode is that (it’s supposed to be marked D - something), but I really don’t know the exact diode to replace it.
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Should I replace the Main 5V Filtering MLCC Capacitors (These are the tiny, light-brown/tan unlabelled ceramic rectangles near the power input or the main processor). Because they are wired in parallel, a single cracked capacitor will cause all of them to beep on a continuity test. After removing the black diode, one of them beeps, and the other one not - in continuity test. So, I’m assuming I have to replace the one beeping - perhaps both to be on the safe side - or future proof. Again I don’t know the kind/type of capacitors in need. Does anyone here is aware?
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Should I check the 3.3V Step-Down Voltage Regulator? I cannot figure out which one on the board is.
Any help, experience or else would be highly appreciated.
P.S. I will also send an e-mail to the support of NI, just in case.