Sequential Circuits Six-Trak -1983    Weight = 17.5 Lbs. Number mfg.=? MRP=$895?

User Manual: Synthesized dreams download or Manual Manor
Reset Proceedures: Six Trak reset notes from NoteIt
Operating System code: EPROM version 11 or EPROM omni off(if for some reason need v2 or v9 let me know)
MIDI or other control protocol: Useful Sysex info from NoteIt's Site
Software related Links: Six-Pat Dos editor
Patches or knob settings: Collection of patches fro NoteIt etc.
Circuit Overview: below
Scematics/Service Manual: Analog Hell or Manual Manor
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors misc
Uncommon chips/modules used: AD7541 DAC, 8253C, Z80, CEM3394 voice on a chip
Modifications:Output Modification for six individual outs Firmware BUG FIX and NEW FIRMWARE!by Tauntek
General Info Links: Vintage Synth Explorer

Circuit Overview:
     The first Multi-Timbral synth. six track sequencer and arpeggiator. Digital control of Curtis CEM3394 'synth on a chip' with nothing particularly surprising I suppose. Single knob data entry and numpad parameter and patch entry.

Service Tips:
     These machines auto-tune every 30 minutes. Or you can init the process with hidden function Patch Rec+6 as I recall. Look at the hidden functions before you start work on this machine. There is also a reset proceedure in the manual someone said. I've not had to use this. Recent repair had a defective DAC which is also a little hard to find. Here are those functions not shown on panel:

Below is a list of Midi commands:

CONTROL RECORD + 0- dump current sequences and stacks
CONTROL RECORD + 1- enable/disable program change
CONTROL RECORD + 2- dump current program (sysex)
CONTROL RECORD + 3- center pitch wheel (for service use only)
CONTROL RECORD + 4- enable/disable wheels and parameters
CONTROL RECORD + 5- unknown
CONTROL RECORD + 6- manual tune
CONTROL RECORD + 7- zero DAC (for service use only)
CONTROL RECORD + 8- basic/raw patch
CONTROL RECORD + 9- tune test toggle (for service use only)

TRACK RECORD + 0- unknown
TRACK RECORD + 1- Mode 1, Omni on/mono off
TRACK RECORD + 2- Mode 2, "Double Mode"
TRACK RECORD + 3- Mode 3, Omni off/mono off
TRACK RECORD + 4- Mode 4, Omni off/mono on
TRACK RECORD + 5- Shows software version
TRACK RECORD + 6- save the base channel
TRACK RECORD + 7- local on (enable keyboard, etc.,..)
TRACK RECORD + 8- local off (disable keyboard, etc.,..)
TRACK RECORD + 9- dump 100 programs 

NOTE ON EPROM versions from Greg Montalbano who took time to investigate my finding that a six trak I sold recently had omni off when it booted:

**OK, here's what I've found with my unit:

**Using version 11, the MIDI mode will be memorized -- if you set it to Omni **off, it will be that way on power up. Works for modes 1, 3 and 4.

**The version 9 you sent is the same one I have. It powers up in mode 1 (omni **on, mono off) -- changes are NOT saved in memory.

**What I find interesting is that NONE of the versions will save the basic **channel -- it always powers up on 3.
--------------Thanks for checking that Greg. I'm totally baffled now by how the one I had booted refusing to acknowledge messages on anything but channel 3. When I get my new burner I'm going to try both versions in my old machine sn.799 and see what it does.

Output Modification:

Many have wanted the mod now gone from NoteIt to give individual outputs. SInce the outputs can all be merged (to a current summer) on the 3394's, one would have to install individual buffers (A quad op amp and a dual to accomplish having six would seem most efficient. TL084 and TL072 would work fine) and then run the outputs direct to the jacks for lowest noise or include a protect resistor in series if you're afraid of having something get damaged ..1K typically. Remember for quieter results you can always just rig a cord if you have a 1K resistor in that the unbalanced output end on a 1/4" jack for instance has a two wire coax coming into it; the other other end tied into an xlr and into a mixer that subtracts pin 2 and 3 to get the signal. Anyway tied shield to ground from pin 1 of the xlr. Pin 2 direct to top of the 1/4". But pin 3 of xlr should tied to a 1K resistor inside of the jack housing of the 1/4" jack. THen tied the other end of the resistor to shield and voila you have a simulation of a balanced output where all the common noise in the two lines gets subtracted away!

I have lots of parts for these. Let me know if you need anything and I have a scrap case at the moment even but no knobs. I did come up with a near fit solution for the rubber buttons and have some pares of those. I think most have arrows on them as I recall.
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