Clean and Repair
Since Wally was in boxes for over a decade, and those boxes were stored in my garage, some parts of him aren't working at 100%. Pretty much all of his potentiometers are scratchy, and a number of wires had come loose.The VCA and LFO are in the most serious need, with the other modules being only intermittently scratchy. Some DeOxIt should fix things up.
The Noise and Dark Star modules actually had some broken wires in them. I've already re-soldered them, so they're working well enough.
Side note: actually, the Dark Star wasn't working at all. In fact, I'd never gotten it to work, since it was one of my earlier projects. With a little help from the good people at Blacet Research (who made the Dark Star) and some diligent circuit tracing, I think it's mostly working now. It's a strange enough module that I'm not entirely sure. But it responds more predictably to its controls now, and I've managed to CV all the parameters successfully, so I'm going to say it's working now.
Tuneups
The MIDI->CV converter and my VCO both have a lot of trimmers in them. It seems like almost all of them need to be trimmed.
The MIDI->CV box has a trimmer that tunes 1v/oct sensitivity. If you know anything about guitars, it's almost the exact same thing as setting intonation - the pitch of each octave relative to the other. The goal is to get exactly one octave for exactly one volt. The control is VERY touchy though. I got it pretty close the other day, but it might still be off. It would be much easier if this trimmer was a multi-turn trimmer, but it's not, and the PCB isn't designed to make it easy to swap one out.
The VCO has trimmers of its own for mostly the same purpose. That's right, both the MIDI->CV and Oscillator can go out of intonation, and they both need to agree with each other. In addition, this VCO has a radial octave dial that lets you pitch it up or down an octave relative to the input control. At least one of these is out of tune with the others. That will be "entertaining" to adjust as well. Fortunately, Ric built these all as multi-turn trimmers, so I should be able to get very precise trim.
I suspect the VCF has a similar v/oct adjustment, but given my current inability to put pitch CV through to both VCO and VCF, it hasn't come up yet. :)
Circuit Upgrades
The Attack/Release module, based off of a modified circuit in the Barry Klein book, is pretty good, but the timing control pots are linear 5M ohm pots. While they have VERY long decay times, their precision for short times is touchy. They need to either be replaced with Audio taper pots or converted with that "add a parallel resistor" trick. Since the pots in that circuit are just "rheostat" type variable resistors, and I don't mind having my resistance cut in half, I think I can get away with it. Or maybe I'll just buy 4 5Meg Audio taper pots and be done with it.Another upgrade is to replace the second AR's gate input jack with one of those "switch normal" jacks, and permanently hook the "normal" connection to the first AR's gate. That way, I can run them both with one signal, and only break the second one free if I plug in a second signal. I've hacked this with an alligator clip, and it's very useful. I need the different jack/switch part to make this a permanent change though.
I plan to do more with this sort of "normaling" in other places.
Much Ado About Jacks
I need to deal with the heterogeneous jacks issue. I can't really upgrade the 1/8" jack modules to 1/4", but I can replace the banana jacks in my VCO. The panel was already drilled for the larger jacks, so it's really just a monster soldering effort. There are 15 jacks to upgrade. Fortunately, I have 20 good quality jacks left over from the Old Days, so I can do the upgrade for nothing but time. I'll admit that the job scares me a little, since I've never been good at panel hookup.The FracRack banana modules are a bigger problem. There just isn't the room to upgrade them in-place. I might be able to 1/8" jack them, but I think I might want to re-panel them.
FracRack Modules
These modules, specifically the Noise, LFO, VCA and Output modules, present a problem. For one thing, since they were the first things I had ever built, they're cobbled together on perfboard and not well mounted to their panels. They also have banana jacks, and can't possibly fit in their same sizes with the larger jacks. The FracRack is pretty tight for space as it is.
Consequently, most of this work seems like it's going beyond First Steps and into Next Steps. I'll need to keep these modules around, since really all of them are essential to Wally's utility as a musical instrument.
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