Board Burnout!
The other day, I made a mouse driver for my senior project, and as a test, I hooked it up to a video controller to display a cursor that’s controlled by a mouse. It was all rather exciting, having the cursor move around on a screen. As I was working on another project, I let my board run that configuration for about an hour or so. Suddenly, the screen went black and my board shut down, smoke coming from somewhere around the power regulation area. After unplugging everything, I discovered that a small transistor by the VGA port that had blown, and the power light wouldn’t turn back on. I suppose the fusion of an old monitor, an old mouse, and operating for too long led to this transistor burning out.
After contacting Digilent, I learned that returns for manufacturing defects have to be within 30 days of purchase. Considering I got the board about a year and a half ago, I’d have to either get a new board, or try to repair this one. I got the part number from them and ordered plenty of spares, as I had never soldered an SMT component by hand before. I just spent about half an hour figuring out how. I learned first that getting the transistor to stay in place is quite a challenge, and that a slightly magnetic X-ACTO knife makes for getting it in the right place to start with difficult. Desoldering the burnt transistor also made for a grand ‘ol time.
To solder the transistor, I cleaned off the pads and the area around it, which was a bit of a mess because of the other transistor. Then I got some solder on all of the pads, which caused them all to bump up and constantly shift the position of the transistor. After it had been pinned down in place by end of a wire, I tried to secure just one contact. Not trusting that I hadn’t overheated the transistor after ten minutes of trying to solder, shifting, placing, and soldering again, I kept throwing out transistors and getting new ones. By the fifth transistor, I was confident that I didn’t damage the component. The other two pads were easy to solder down because the other was holding the transistor in place.
Here’s my handywork:
The moment of truth: I plugged the board in, the power light came on, and a configuration worked. Woo! I avoided having to buy a whole new board, and got a little experience with SMT soldering.
Ben Oztalay
