Oberheim Matrix-12 Synthesizer Power Supply Issues RESOLVED

In this video I show what I did to resolve my power supply issues on the Oberheim Matrix-12 analog synthesizer. Symptoms were intermittent non-boot, locking up, and the dreaded Voice 1 Processor Malfunction message. Along the way I'll talk about how the power supply works and how it is different than many synths from the era prior to this. Even though the Oberheim Xpander is a little different than the Matrix-12, its power supply works exactly the same. This may not enable you to fix your Matrix-12/Xpander completely, nor answer ALL questions you may have...but hopefully it will be helpful information.

YOU ASSUME ALL RISK WHEN REPAIRING YOUR OWN ELECTRONIC INSTRUMENTS! There's no shame in asking a friend for help or taking it to a reputable synthesizer technician. BE SURE TO UNPLUG THE SYNTH PRIOR TO DOING THIS KIND OF WORK.

0:00 Introduction
1:10 Getting Started
1:54 Dealing with an SMPS
3:16 Why did Oberheim use an SMPS?
3:40 Why I'm NOT going to troubleshoot this power supply
4:38 Power Supply Restoration and Results


Here are the Mouser parts numbers:
Power Entry Module - 871-B84771A0001A000
2W Shunt Resistors 0.1ohm - 667-ERX-2SZGR10V
sorry I don't have capacitor numbers, I did that work 2 years ago

Oberheim Matrix-12 Synthesizer Demo #7

The Oberheim Matrix-12 was cooperating today, so I thought I better make a video before something happens again. Using some reverb and delay, recorded direct and no audio post processing.

Roland Alpha Juno-1 Synthesizer Demo #2 New Patches

Rolling out some new patches for the Juno-1/2 available on my download post for this blog. A full bank of patches including the sounds from Demo #1. In this video I have selected a few of my personal favorites: bass, arpeggios, and soundscapes/pads. There are copious amounts of Big Sky reverb, a couple of sounds use the Timefactor delay. Basses don't usually need anything. Sounds were programmed using the indispensable Stereoping synth controller, also used briefly in this demo. Recorded direct through a Mackie 802-VLZ mixer to a Tascam DR-05.

Rundown:
0:00 Cloud Bank
0:31 Tinsel
0:56 Aurora Pad 2
1:14 Bass Arp 01
1:30 Strangers
1:54 Particle
2:14 Mod Bass
2:25 Juno Crush
2:37 Alpha Synth
2:51 Micro Fab
3:08 Toys
3:24 Bass Pedalr
3:35 Mono Bass
3:43 Shimmer
4:10 Synth Mutes
4:25 Fake Wurli
4:46 Choir
5:21 twilight
6:07 Psycho Sweep
6:32 Pure Space
6:59 Detroit
7:24 Ascension

Design Philosophy Behind the DRE4MTR4CK Eurorack Sequencer

Sequencers. It seems the market is inundated with these things. Not long ago your choices consisted of the MMT-8, an MPC, or one of Roland's MC series. And if you wanted CV and not MIDI, good luck finding a high-priced analog modular piece. Nowadays there's the Beatstep, SQ-1, and a flood of sequencers in the Eurorack market. Let's not forget about the Social Entropy Engine, that thing is absolutely fantastic. Why would anybody want to make another bloody sequencer?

It also seems everybody is also churning out Euro sequencer modules. I made a deal with myself not to design any Euro modules. That is, unless I had a compelling idea. An idea came along indeed, and it has consumed me. I've owned and used many of the MIDI sequencers mentioned above. They all come from a place of music composition, assembling songs together in very predefined manner. Ever since getting into Euro, this elusive thing of organic melody progression has been tugging at me. There are some interesting devices going this direction such as the Pressure Points. The Hologram Dream Sequence has been especially intriguing, the way it octave shifts incoming audio. There are Euro devices that quantize pitch cv, and devices which feature all manner of pitch scales. I've been wanting something more organic, intuitive, and could serve more VCOs at the same time.

Messing with this idea of organic melody progression, it had to have something more: Polyrhythmic. So many sequencers these days seemed chained to shuffling/swinging everything to a master clock. I wanted it to be able to serve multiple incoming clocks, and maybe times when I wanted none at all. This is where the idea for the DRE4MTR4CK is really coming from. A sequencer that has the freedom (flexibility) to be used in many different Euro module configurations.

And lastly, it had to be compact. Large modules that are case hogs are off-putting, that's my valuable rack real estate! So 10HP was the target, but the hardware couldn't fit. 12HP gives a little bit more breathing room for handling the buttons and data pot. Sure I thought it would be nice to have a display that would show the note values. But again, that would have become a bigger module, and I kind of like the idea of note programming being intuitive. Who cares what the note names are, I have a Beatstep Pro for that - so let the ear decide these things as you go.

Designing a module such as this has its challenges. Things happen when you are designing a module on your own, and building it with your own two hands. Just last week I thought the project was dead in the water. But I persevered once more. I have risked everything, all my cards are on the table. The DRE4MTR4CK has been my labor of love for over 2 months in the making. With hard work, persistence, and steady dedication the DRE4MTR4CK is now a reality. An organic melody progression sequencer, with polyrhythmic capability.

Evolving Chords Eurorack Synthesizer Performance Demo

Performance using evolving chord changes with my custom DRE4MTR4CK Euro module. It has 4 independent tracks of polyphonic pitch control:
Track 1: Pittsburgh Synth Box, internal filter
Track 2: DNA Symbiotic Waves, JP-6 Filter clone
Track 3: Disting MK3, Doepfer SEM filter
Track 4: Rings, no filter.

Clocking direct to envelopes, triggering pitch changes manually. Track 1 pitch CV is going through a PM Toolbox slew limiter. Mix is going to Timefactor delay. Recorded direct through a Mackie 802 to a Tascam DR-05.

DRE4MTR4CK Eurorack Sequencer User Guide

The DRE4MTR4CK is a simple and intuitive Pitch CV sequencer. It has 4 steps, and it has 4 Individual tracks. Each track has its own clock input, clock output, and Pitch CV output. In this way, it can behave like 4 completely independent sequencers.

In this video I show how to use the DRE4MTR4CK in more detail.
0:00 Introduction
1:23 Installation Options
Correction: the graphics say -5v when it should say +5v (positive 5v).
3:06 Boot-Up Defaults
3:32 Connections and Operations

DRE4MTR4CK is a custom module built by hand. Full specs available on my previous post.