Through my own sheer stupidity, I've just powered up a brand new GSM shield with a 9v power supply instead of the required 5v supply. To boot, I think the polarity of my power supply is the opposite of what is required.
This caused a surprisingly spectacular spark from the C3 capacitor, which has basically exploded, and the 29302WU transistor next to the power socket looks like it could be a little scorched (although that could be fallout from the cap.
Am I likely to have fried the whole shield? Or could I carefully replace these components and start again?
Well don't be surprised if the board is or becomes unreliable, its had a shock(!).
The capacitor may have acted as a fuse and protected the rest of the circuitry,
but after it exploded it no longer protected the rest of the board!
My rule for wiring things up is to always double-check the wiring before powering up.
Any source of power should have its polarity fixed by the connector or else you need
to colour code it red+black so you can't make such mistakes!
If you have a bench supply you can initially power up with current-limiting and be ready
to switch off if anything suspicious is happening.
I still don't understand why the more expensive products don't come with at least a diode to stop this kind of thing happening, i'd like to see more basic safety features introduced into the Arduino World .... (it is after all, aimed at beginners)
That looks suspiciously like the Seeed SIM900 shield that can be bought on eBay for less than half the Maplin price, albeit it has a white pcb rather than a green one. So if it does turn out to be damaged then it's not quite so expensive to replace.
cjdelphi:
I still don't understand why the more expensive products don't come with at least a diode to stop this kind of thing happening
As has been discussed before - are you now proposing a series diode which impedes the regulation of the power supply and if so, silicon (0.7V drop) or Schottky, or are you suggesting a IN5401 in parallel with the input?
Electrolytics are the worst. I once put one of those on a board back to front. Heard a fizzing sound so took a closer look (didn't think of removing the power). Gave me a black eye as the outer case came off like a bullet. It'll never happen again.
Now if only we endured that much pain from putting a single = in our code when it should be ==. I'm sure this common mistake could be eradicated too.
