More Synth Maintenance Completed

It’s been a busy week behind the scenes at Studio Nebula. Not a lot of creative stuff going on at the moment, but I’ve taken the time to give much-needed TLC to some vintage gear.

Repaired Sequential Six-Trak!

Six Trak

Let me know if you're looking for a recently-serviced Six-Trak in excellent shape, with the latest / greatest firmware!

There was a faulty capacitor in the power supply section. She’s running like a top now, and I installed the Bob Grieb / Tauntek firmware which fixes some MIDI bugs and adds some cool new features. I plan to do a subjective Six-Trak vs. Multi-Trak analysis (possibly with videos), then I expect to put the Six-Trak up for sale. This unit is in great shape, so contact me if you’re looking for one.
Six-Trak Rear Panel

This spotless Six-Trak could be yours!

Installed the Organix JX-3P MIDI Expansion Kit into JX-3P!


This board must be removed from the JX-3P and modified for the Organix MIDI Expansion Kit.

The Organix mod is a straightforward installation, but fairly invasive. After you assemble the little circuit board and put it in the cute little box, there are several traces on your JX-3P MIDI board to cut, components to remove, places to solder wires to. The MIDI CC features seem to work flawlessly so far. I also replaced the battery. Sorry, I forgot to take pictures of my work! I am working on a Logic environment to allow full control of all JX-3P parameters from the computer screen, and also to use the JX-03 Boutique synth as a control surface to program the JX-3P!
Lithium Batteries for JX-3P (CR-1/3N, left) and Multi-Trak (CR-2/3A, right)

Awww, buddies! The CR-1/3N (left) is for the JX-3P, while the CR-2/3A (right) is for the Multi-Trak. Solder tabs installed locally!

JX-3P Logic Environment

My Logic Environment to control the Organix-modded JX-3P is a work in progress.

I Built a bong0!

Life In Hell Bongo

No, not that Bongo.

A few weeks ago I ordered some parts from “Modular Addict” and I decided to tack on a couple of inexpensive PCB/panel sets. This simple Eurorack module, called “bong0″ from Nonlinear Circuits, is one of them. Apparently it can do little percussive sounds, as well as drones. I haven’t powered it up yet. I just need some IDC ribbon connectors for power, and it should be good to go.
NC bong0

Completed Bong0 Eurorack module. Piece of Cake.

The Future’s So Bright…

Shades PCB

"Shades" PCB.

I got started building the open-source version of the Mutable Instruments “Shades” Eurorack module.

Shades is used for for CV offset/invert/scaling – it makes no sound of its own. The project Bill Of Materials specifies some really hi-spec components. Assuming I can get it working, it will come in very handy for massaging voltages between my non-Euro gear, like the Minifooger delay, the MicroBrute, the MS-20, the Boss Micro-Rack stuff, etc.

If I had this one to do again, I think I’d just buy the module pre-built. I don’t particularly enjoy working with 0603 SMT components, especially at home. I am impressed with the circuit design, though.

Got a crude tape echo happening!

I modified a Marantz PMD-430 cassette recorder so that the pitch control works while recording. This makes interesting dub-style delay regeneration effects possible when using the deck as a simple tape echo.

The PMD430 (CP430 in Europe), as a stereo deck, can do ping-pong stereo echo effects, as well as double-generation double-delay time (by routing the signal into the left input, the left output into the right input, and ultimately getting the delayed signal from the right output. This is in stark contrast to the (monophonic) Marantz PMD 221/222s which are more frequently used for this purpose. Also, some people build a little external buffer/mixer box for this application, but I found that it sounds just fine in the effects loop of a Mackie LM3204 mixer (returning into a full-fledged channel strip, you need only adjust its send level to achieve regeneration).

The mod is simple: cut one trace and bridge two solder joints. I admit it’s ugly, but the little piece of bare wire and a solder glob will more than do the trick. Two clickable pictures of this mod are below, but details will follow in a future article. Feel free to leave a comment if you need more info.

Photo of Modified PCB

Marantz PMD430 / CP430 Pitch Enable Mod Picture 1

Photo of Modified PCB

Marantz PMD430 / CP430 Pitch Enable Mod Picture 2

Replaced 4 coin cell batteries in my Yamaha TX416!

Yamaha TX416

My TX416 got 4 fresh batteries!

(It’s like a TX816 or TX216 but with 4 TF1 modules). I learned that after removing a TF1 module, you should wait for at least an hour before you test the battery on the PCB with a voltmeter, because there is a residual voltage (presumably in some large capacitors) that will mislead you! It also might not hurt to hold a resistor (approximately 100 ohms) across the battery terminals for a few seconds before you start probing.

Received some BBDs!

These MN3009 Bucket Brigade Device ICs are here to repair the noisy chorus in my Juno-106 and JX-3P. After buying them on eBay I am skeptical about their authenticity for a couple of reasons:

  1. They do not look the same – in each of the two photos below, the IC on the left has a circular “Pin 1″ indicator while the other does not. Also, the underline under the final “9″ is different on each IC.
  2. They were bought from an eBay vendor who some users have reported receiving counterfeit ICs from

I plan to try these in my Juno-106 as soon as possible. I will report what I find. Here are the pics:

MN3009 IC x2

Suspect MN3009 BBDs from eBay vendor - pic #1

2x MN3009 IC

Suspect MN3009 BBDs from eBay vendor - pic #2

I’ve been busy!

Other jobs I plan to finish up this month:

  1. Roland Juno-106: HPF slider, Volume Pot, BBD repair.
  2. Roland JX-3P: Volume Pot, BBD repair.
  3. Roland Jupiter-6: Bender Board troubleshoot, 6-voice alignment, VCA level slider repair.
  4. “Mutated” Shades: Finish module.
  5. Sequential Multi-Trak: Battery Drain Mod, Grieb Firmware.
  6. Realistic / Moog MG-1: Octave Divider Repair. (and latency mod?)
  7. Marantz PMD-221: Modify for pitch control during recording.
  8. Korg EX-800: Wood sides, Moog Slayer, FM. To sell.

Please slip some food under the door for me.

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