Tuesday, October 13, 2009

Bi-N-Tic Filter: Panel Wiring

I just finished wiring all of the panel leads to the board. Here's the results:

If you look at the right edge of each of the four pots, you can see that they have a locator pin. I'm still trying to decide if I want to use them, or cut them off. If I use them, I have to drill seven additional holes in the panel. Lot of trouble. On the other hand, if the locator pins are used, it pretty much assures that the pot bodies won't rotate behind the panel and mess up the knob indexing.

For my mod, which will provide for passing the Q4 instead of the Q3 bit from the counter to the most significant bit of the muxes, I had to solder a wire directly to that pin of the 4024 counter IC.:

It's a bit hard to tell from the photo, but that pin of the IC is bent outward and is not in contact with the socket. The yellow wire soldered to it will go to the panel switch for this mod. The output from the switch returns as shown in the next photo:

The blue wire brings the signal back to this otherwise-empty hole under the pin socket that I broke off.

One of the few things I don't like about this board is that the various points on the board, where the pads are for the wiring to/from the panel, don't have ground pads in the vicinity. This means, among other things, that you really can't use twisted-pair wiring. In fact, grounding points are kind of scarce. The only convenient place to bring out grounds is to use the set of pads that are intended to be used for a Eurorack-style power connector. It has six pads connected to ground. I've soldered in two wires, with the idea that one will be the ground for the input signal jack, and the other will be the ground for all of the control and output jacks. But I'll look at again when I put together the panel. Here's the ground wiring; note the MOTM-style power connector above:

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