Interesting, thanks for the informative response. Not much info on D17 out there, and it seems like no one else has had this issue so a strange thing to have occurred. I've emailed Element14 and will hopefully be able to send it back.aTao wrote:D17 is an overvoltage protection system, in the case of "extreme" voltages its resistance breaks down and conducts large currents.
If it is "doing its thing" then you have:
a) a PSU that is outputting significantly more than 5V for at least part of the time
b) a faulty D17
c) a D17 with a wrong value that sneaked into the production chain.
To properly measure you PSU voltage you would need an oscilloscope, or you could have it charge a capacitor and measure that voltage.
Might be best to try a different PSU. But it does seem most likely that your D17 was faulty and died (they should be able to take a massive hammering), in which case it should be covered by warrantee.
I bet that in this power configuration you were actually back feeding the PI from the HUB, that is instead of feeding power from the micro-USB port you were actually applying power via its normal USB output. Normally this isn't too big a problem, but one hidden problem with it is that power no longer passes the input polyfuse. Now if for whatever reason there is a millisecond pulse that raises above ~6V the over-voltage protection diode will trigger and short the 5V supply to GND! As there is no polyfuse anymore to block current, and if the hub is also cheap and doesn't have any over-current protection itself, all the power the PSU can deliver keeps flowing through the over-voltage protection diode until it burns out completely! Which wouldn't have happened if you had fed the PI the correct way through the micro-USB port!jascination wrote:I have a very simple/standard RaspBMC setup, like so:
USB hard drive -> Powered USB hub -> RPi <- Wifi Dongle
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