So back in 2018 when I got my midibox sequencer v3 working and then my midibox SID stopped working I started looking for something else to control with the sequencer. I reached out to some local musically inclined friends to inquire if they had any MIDI synths that were gathering too much dust and they may want to part with at a decent price…or even any I could borrow for a few weeks just to put the sequencer through it’s paces.
The only offer I got was a friend who gave me an edirol USB midi interface he didn’t use anymore and a “set of bass pedals I picked up years ago that don’t work - they just hum and make a click when I hit any of the pedals”. I didn’t really want bass pedals…but…was intrigued so said I’d take them.
This is what he showed up with:
A set of late 70’s early 80’s Crumar bass pedals. No MIDI which at the time was what I was really interested in. They’re basically a CEM3340/3320 based analog synth. I immediately noticed that the sustain control was broken and though “oh, this is an easy fix…it’s just mechanical!”
Then I opened it up to see about fixing that…I have to assume someone has already tried to repair these and this is not factory wiring:
Then again maybe it was and that explains why Crumar isn’t around anymore 
I mean…this actually does look like it may be from the factory (hello there CEM3340!):
The sustain control was badly damaged…the pot itself is still ok but the “knob” is totally broken where it clamps to the shaft:
But I have a 3D printer and some CAD skills…so 15 minutes in Fusion360 and an hour on the printer solved that:
I even have orange filament but the clear was loaded into the printer so I just went with that to test how well my replacement works…if I get these pedals working again then maybe I’ll reprint it in “proper” orange.
But - this was just a bit of fun because turning the pot manually I confirmed that the broken sustain wasn’t the reason this thing only generates clicks.
I’ve tried to track down a schematic for it but haven’t found one for free. Have found a few places selling them for $25…but…I’m not really interested in putting that much into these right now 
And given the status of the wiring and how many factory bodges there appear to be I’m not sure just how much the schematics would match up anyway.
Every couple of months I pull them out and think about trying to fix them again. But…they’re just so big and heavy that they take up too much space even to work on them. And with no CV or MIDI and me having horribly uncoordinated feet I doubt I’d even use them if I do get them working. But…I still kind of want to get them working just to do it.
Next time I dig in on them I figure I’ll start probing with the oscilloscope around the output of the 3340 to see if it’s an oscillator or VCA issue. Since I do hear a click when hitting any of the keys I’m guessing the VCA is working and it’s the 3340 or something around it that’s not happy. Though given the number of crazy poorly done “repairs” on this thing it could be almost anything at this point.
I’m half tempted to just desolder the 3340/3320 and re-use them in something else…but at the same time I hate the idea of scrapping them entirely.
