This is what happens when you accidentally plug the power in backwards on a Printrbot Jr. (due to a miswired ATX12V extension cable). Hopefully I only have to replace the board and none of the motors. An expensive “oops.”, entirely my fault.
Ouch.
Ya know… If you’re quick enough, you can get that magical smoke back in there…
Cable that caused the problem on the left, good one I’d been using on the right.
damn! I hope it’s not a costly mistake :S
The motors are likely fine. Damn things are nearly indestructible.
Hey, many of us have learned in the same manner, sometimes more spectacularly, other times hidden from view.
My first spectacular failure, I had a spool loaded on top of a Mendel/prusa, and started a print over night. Spool fell off into the X-Axis, causing the X- to MAX, then the spool continued to fall onto the heatbed. where it promptly broke the Hot end retaining collar, and then the extruder continued to drive fitment until the Hot end, snaked it’s way into a Stepper controller where it finally stopped moving. but it did NOT stop heating. the hot end burned it’s way through the Stepper Driver I.C. it took out not only the Stepper, but also the Ramps 1.4 and it’s accompanying Arduino Mega.
SO Yeah, welcome to 3D printing!
your now “One Of Us!”
Yeah, that’s a problem with the printrboard. The motor drivers are soldered down so if they fry, there goes the whole board.
I plan on back-porting the design to the teensylu, once I get enough money for an eaglecad license.
Its not too bad… I had to replace a driver on the Brainwave (those things suck as they are only rated for 800mA) and it wasnt too bad: use an exacto to cut the legs of the chip to release it, swipe the remaining legs with a soldering iron to clean up the pads. New chip is put in place, pin one corner leg with solder to position it, flood solder over all the legs, and clean up with solder wick. Ok that sounds exhausting…
@Brian_Evans is completely right here. The driver chips are really not that hard to replace with a decent soldering iron. And no respectable hacker is complete without a good soldering iron.
And… The other three ATX12V extension cables in the order… Were wired correctly. My bad luck to grab the one that wasn’t and be in a hurry. I’m going to have to replace this entire board, its not just the motor drivers. Won’t even boot up anymore.
Did I mention the USB cable was burning hot? 
its toasted. Luckily it didn’t take out the PC’s USB port with it.
A wise electrical engineering mentor once told me that “you can’t let the smoke out of electrical components”.
I wouldn’t worry about the replaceability of the drivers - they rarley fail if you don’t abuse them (unplugging the motors while powered…). When the drivers fail e.g. due to over/undervoltage, the whole board, including any USB to Serial converter and the Atmega, gets fried and i wouldn’t worry about the drivers themselves.
That said, if I’m buying a set of electronics for my next printer it’ll be a modular RAMPS. The entire setup (mega, ramps, 5 stepsticks) is about 80 bucks in chinese clone form on ebay.
I feel your agony, sometimes experience is realizing you’ve made this mistake before. often this will lead to despair and if that’s the case we’ll all be cheering you on to dust yourself off and get back at it!