Guess what I bought last weekend.. :D
Yes, it’s the silly looking (and ridiculously overweight) guitar synth straight from the 80s, made famous by Flight of the Conchords.. the Casio DG-20! You probably now know what to expect to be reading in this blog over the coming weeks.. ;)
Once again, a repair documentation just for the sake of having these bits of info written down somewhere. Notebook as good as any ;) .. Just to intro this monster of a synth, here’s what Peter Forrest writes about it in his book “A-Z of Analogue Synthesizers“:
The Matrix-12 is a 61-note synth with three big LCDs, six value knobs and about 60 switches on the front panel. Internally, it is 12-voice polyphonic and 12-part multitimbral, each part responding to its own MIDI channel. Each voice provides two big fat VCOs (offering triangle, saw, pulse, and noise waveforms), one 15-mode VCF (offering various low pass, high pass, band pass, notch and phaser types, all complete with resonant squelch), five LFOs, five envelope generators, 15(!) VCAs, and one FM modulation generator for oscillator sync and cross-mod madness.
There’s also a lag generator (a sort of portamento that can be applied to anything, not just pitch), three keyboard-tracking generators, four ramp generators (a very simple two-level envelope) and, finally, one noise generator. And that’s just one voice. There are 12 inside here! All this sound-creating muscle is useless without an equally powerful control system, and to this end Oberheim came up with the ‘Modulation Matrix’ from which the machine takes its name. This system enables 20 connections per voice between virtually any parameters. For example, to increase the speed of an LFO with time, select LFO speed as the destination and a slow attacking envelope as the modulator.
The Matrix-12 that landed on my desk was in need of lever potentiometer and rotary encoder replacements. As is, the lever potentiometers had problems tracking smoothly (eg. resulting in pitch “warble”) whereas the encoders did a lot of skipping back and forth.. Working but unusable, so to say.
Ever wondered what a +50 EUR DIP chip circa early 1980s looks like? Well, here you go:
Took “only” about three years to source two of these in NOS (new-old-stock) condition, so you can guess how big of a victory seeing the second one on my desk felt ;).
Possibly worthwhile noting from the picture above that I’ve added sockets for all custom chips. This speeds up cross-testing. For some reason Yamaha has decided to use wider-than-usual pin spacing on the PCB, thus the pins of the sockets had to be bent to match. The spacing is somewhat equivalent to the what you might see on DIP chips when taken fresh out from a container tube, so I’m thinking maybe they designed it this way possibly to speed up assembly(?)..
Anyway, this finally makes my CS15D fully functional and oh boy does it sound sweet! Truly, these Yamaha VCF chips have a character unlike any other VCF chip of the era. It will definitely be interesting to do some actual testing with how well their sound will sit in-the-mix :)
Despite there probably are plenty of instructions like this out there, I figured I’ll do one anyway. The reason: A few weeks ago, I managed to drop my iPod from the height of about 1,5m while the harddisk was spinning.. *Click-whirr* bye bye hd and a round of applause for me \o/. Knowing I’m gonna replace the part myself, why not also document while I’m at it.
Sooo.. Sourcing a spare, no problem. The one I bought is a 240Gb Toshiba (model MK2431GAH) I found on eBay. Even the shipping turned out super-fast; spare part on my desk in less than a week after paying for the order!
In for repairs early june, a couple of HTC phones with their USB connectors in need of replacement. The other one a TyTN and the other one a Touch Dual, both using a proprietary HTC connector. Just take a wild guess which was the most problematic bit of the repair.. Neat that I wasn’t the one who had to source the spares ;)
I’m moreover writing this post just to have the few silly bits of info logged up somewhere in case I need them later, not for the sake of documenting the actual repair (it’s only about swapping connectors anyway). In case you ended up here looking for additional info on this connector but happen to know something beyond what I’ve written, please add that to the comments. If you happen to know a any online shops that sells these connectors, that bit of info is much welcome.