Things That Go Boom In The Night...

It is a truth universally acknowledged that a mechanical engineer will invariably blow up the electrical components of their current project.

Case in point: I just finished assembling a Prusa i3 Geeetech 3-D printer and was plugging it in for the first time when the large, 1000 microfarad capacitor on the main control board (the Sanguinololu) exploded in my face. I had spent an entire week's worth of scotch-fueled, STNG-powered evenings carefully assembling my 3-D printer. Step by step the x, y and z axes came together, the aluminum frame was screwed together, the motors mounted and the wiring very cautiously completed. Monday was the moment of truth - I was ready to plug the power supply into the wall.

But when I did, I smelled something funny and then I heard a bang as loud as a party popper. So I turned off the power supply and had another glass of wine.

(The picture on the left shows the remaining terminals and base in the top middle of the image.)

There are 2 ways to blow up a capacitor:

1. Reverse the polarity: if you reverse the positive and negative power inputs to the capacitor, it causes the capacitor to heat up and a gas is formed which creates enough pressure inside the capacitor to cause an explosion.

2. Excessive voltage: if the input voltage is significantly greater than what the capacitor is rated for, the excess voltage will also cause the capacitor's terminals to heat up and produce a gas that causes the capacitor to explode.

My power supply was set to deliver 220V instead of 110V, and it is also possible that I had the polarity reversed, so I cannot nail down the cause. I do, however, have a solution - look for my next post on soldering and through-hole mounted electrical components!