Heatsink shorted pololu, sanguino can no longer connect

So, as i was placing my pololus back onto my sanguino, and I didn't notice until too late that one of the pololu heatsinks was slightly off kilter. As soon as i turned on 12v I heard that signature short-pop and immediately turned it off. Though I'm certainly not sure of the cause, after some examination the only cause i could see was that the heatsink was slightly over a couple pins on either side of the pololu. I removed the heatsink entirely and tried to connect just through USB, and no result. I (hesitantly) tried powering up again without the heatsink, and did not hear or see any further signs of a short, but I could still not connect. I also tried removing the pololus again and still nothing.

I know that shorts into the wrong pin can spell death, but is there anything I can do to test/fix what the issue is?

Thats bad...

Depends on what pins you shorted, but you have probably put 12v threw your 5v 644p/1284p I/O pins... just about guaranteed to fry the MPU.

Replace the 644p, and prey the FT232RL didnt get zapped too. Does the board still turn up as a serial device for your computer to see? (should still show up as a serial even with dead or removed MPU)

[www.emakershop.com] is a good place to get replacement, pre programmed, with bootloaders etc..

Hi Dust,
Yeah, the heatsink was definitely over 12v.... dang.
Ok, though, a shot MPU isnt the hardest thing to replace. The board does register as a serial device, I assume that means there is hope for the remainder of the board? That poor little sanguino has been through a lot of me learning what not to do
Outside of that, is there an established strategy for keeping the heatsinks from moving about? I had had the thought of putting some non-conductive tape on the exposed metal on the bottom to keep them from from bridging anything in the event that they do slip again, but would that compromise the functionality of the heatsink? I imagine the tape wouldn't last long exposed to that heat, either.
On diagnosing further issues, I don't know anything about the FT232RL - is there any way to know if it is damaged?


Thanks for the emakershop link, those prices look pretty managable.

Re testing the FT232RL, Since the board still turns up as a serial interface this is a really good sign

You can test it, but shorting TX and RX togeather, see the video on soldering and testing [reprap.org]. Watch the video from 5:10 onwards
Do this with the MPU out

Or just wait till you have a new MPU

Re the heat sinks, myne are stuck on with double sided thermal tape and dont move.
This stuff [ultimachine.com]

Update: Excellent advice. I replaced the Atmega and got a handful of new steppers (with properly applied heatsinks!) and I can now step. Thanks so much!