September | 2013 | xbs111.wordpress.com

It’s a tech kind of weekend!

A while back I met a guy named Bob Grieb on the sequential circuits yahoo group who was working on a firmware and memory upgrade for the Sequential Circuits Max. I am a huge fan of the SCI Multitrak as posted here and the Max is basically the same synth in a smaller package with less programming capability ( no editing grid on the faceplate ), performance features ( arpeggiator and wheels ), and an even less colorful color scheme! ( I’ll have one totally 80’s football font on grey sparkle please!!! )

As soon as Bob had kits available i had him ship me a set so i could do some tech work on the weekend. It consisted of a PCB, a new larger ram chip, an eprom with updated OS features, some chip sockets, and a few diodes, resistors, caps, and wires to assemble. He posted instructions on his site to assist in the process as well. Its not too complicated but there’s several steps that are pretty hard if you are not comfy soldering multi pin chips.

1, First i needed to remove the 2 old non writable ram chips from the mother board. Thats right, the original OS didn’t allow you to rewrite the basic patches, although they could be edited via midi and were remembered while the unit had power. The same went for the sequence memory: lost at power down. This was the hardest part of the process. The memory chips are right next to the CPU and had a very tight space between them for desoldering. I chose to use a liberal amount of solder wick to pull the solder from the joints. it took a while but finally the two chips literally fell out without damaging the board!

2, I then assembled the new PCB. Theres a socket for the new ram and the new OS eprom as well as a set of pins on the bottom that sit in the old eprom socket. I then added the other components to the board and checked to see if it fit into the socket on the mother board without touching anything. It looked good and i actually attached a small bit of foam to the bottom of the PCB to relieve the weight of the whole assembly resting on the eprom socket.

3, after attaching the 5 wires for os, ram addressing, and power to the new PCB i was ready to start the Max up! That wasn’t too bad once i got past the chip removal!

At startup the max loads it’s basic patches and default sequences from the new ram location on the new chip. Then it goes through the voice tuning routine as it always would. Pretty smooth actually!

I also did a few other maintenance things while i was inside the max:

1, I gave it a thorough cleaning. 30 years can leave a lot of dust! I also noticed that the metal supports for the mother board were totally untreated metal and they were corroding. They were covered in a fine dust of rust and it was gross. So i scrubbed them in the sink and let the whole bottom plate dry in the sun for a while. I then used a can of Rust-Oleum clear enamel to coat them. This will hopefully help keep them from corroding more in the future.

2 I also removed and cleaned the small red window that covers the led display. I re-taped it on all four sides so it will keep dust out more effectively and look better.

So, the Tauntek SCI Max firmware upgrade adds many features. Here’s a list of them:

1) 100 downloadable programs (Max had 20 that could be downloaded)

2) Storage for ~3200 notes in two songs (Max could store about 500)

3) Unison mode (Max did not support Unison mode)

4) Battery-backed storage of downloadable programs and songs

5) MIDI chan and a few other parameters are also non-volatile

6) Three sets of programs in EPROM, loadable on request:

a) Max orig 80 programs plus Six Trak Unison programs

b) Six Trak orig 100 programs

c) Multitrak orig 100 programs, without chorus and velocity sens parameters

7) Current voice parameters, including any CC changes, can be stored in program #99

8) Program #99 can be copied to any other program.