Part 6: assembling and testing the PCB

Here is where I ran into some PROBLEMS. At some point during my design process, I dropped a very important resistor from the design. This one:

The perpetrator

Unfortunately, by dropping this resistor, I had shorted power to ground along every button in the keyboard. When I got my board, soldered on the parts, and plugged it in, it immediately got EXTEMELY hot. That's when I knew it was bad news. After I figured out what the problem was, I set about fixing it. I had to cut all power from the keyboard and also pin 4 on every chip. This meant cutting 28 traces. THEN I had to jumper a few of the pin 8s back to power and jumper every pin 4 to pin 8 via the aforementioned 10k resistor. It took me several attempts to do this. This is what it looks like:

My poor board!

Unfortunately, I didn't account for all the vias (traces running from the top to the bottom of the board), so I ended up with no power to some of the resistors that set the tones (frequency value). I've since fixed that particular problem in my design and plan a few more alterations before ordering another round of PCBs.

Here's a video of what it currently sounds like: