MIDIBox SID Project Blog

A COMMODORE 64 BASED MUSIC SYNTHESIZER

Wiring the Matrices

First I did the diodes and soldering just the cathodes. The top row of cathode leads I soldered by themselves. Then for each row below I bent the cathode lead so that it touched the cathode lead of the diode below it and repeating that process built the columns for my matrix. Next I added the pin headers and following a tip I found online I held them down with some of the plastic foam my components shipped with. I had to wrestle the pin headers on the edge of the matrix back into their hole after some were accidentally pulled out by the foam, but ultimately I got them all to stay in place after taping the foam down to the perfboard.

So next I needed to connect the anode leads of the diodes to their neighbor pin head. I found for this task it was easier to clip the anode lead fairly short so I could lay it down on the pad for the pin header without disturbing the ones near by. Initially I was still not cutting the leads short enough and they would extended beyond the targeted pad, but later on I started making the shorter to avoid this.

Near the end of this round of soldering I ran out of my old solder and switched to my new solder. Both solders were 63/37 mixes, 0.8mm thick, and with 2% flux, but this new solder just doesn't melt well (I thought my old solder was bad, this is worse). To finish the rows I had to turn the soldering iron up an additional 100 degrees from 760 to 860F. This seems way to hot so I think I may have to invest in higher quality solder instead of $5 spools from China.

The cathode leads of the diodes laid down for soldering.
By carefully pressing a piece of plastic foam over all the pin headers I was able to keep them in place while soldering.
The cathode rows soldered down.
The clipped anode leads bent onto the adjacent pad shared with the pin header.
Anode leads soldered. These are a little long... later I started clipping them shorter so they wouldn't extend beyond the target pad.

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