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By leehambley
Hi all, first post.

I accidentally powered my Redboard with 12v on VIN/GND (Pins 7&8) and burned out a small 2x4mm component between the LM1117 and the barrel jack connector.

I reviewed the schematic at ... rd-V22.pdf and I *think* it's a diode to prevent current from VIN flowing back through the barrel connector, which probably wasn't rated for 12v?

Anyway, I'd love to knowif it's possible to repair the board. I strongly suspect however that it's just fried and I'll be better served by switching to one of the ESP32 series arduino compatible boards, the particle web IDE and tooling was pretty nice though!

I tried powering via USB and the power LED barely illuminates and it doesn't boot correctly.

Image here of the damaged component
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By TS-Chris
Hi Lee, thanks for your post!

You're actually looking at the schematic for a different board, the one you need for the Photon RedBoard is here.

It's hard to say if this is easily repairable or not since I don't know exactly what caused that part to fail. If other parts downstream are affected, it may not be feasible to repair. The part in your picture that failed is a capacitor and reverse polarity or over voltage would cause damage like you're seeing.

My guess is that that cap failed with a short circuit and that's why USB power isn't working. What I'd suggest is to desolder that component, and clean the board under the component and see if USB power works after trying that. If it does, you really should replace that capacitor, but the board will probably run just fine without it.

If the board doesn't work with the capacitor removed, there's more damage to parts further down the line and it's hard to say what else needs replaced. It might not be worth the trouble and expense of replacing parts and just replace the entire board. (Especially if the Photon module was damaged since desoldering that would be a real challenge. )
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By leehambley
Hi Chris,

Thanks for such a fast reply 🎉 -- Thanks for referring me to the correct schematic too.

I was able to desolder that capacitor, and confirm that with that removed I can see place I see the expected voltages on the pins (circa 5V) when powered with USB, but the LEDs are super dim and the board isn't coming up properly.

I guess it's toast, that serves me right for mixing up my 5 and 12v rails !