Sequential Circuits Multi-Trak 1985    Weight = 16 Lbs. Number mfg.= ? MRP=$1499

User Manual: Manual Manor
Reset Proceedures: Turn off for 5 seconds or so. Some machines boot with no sound now and then. Also See the FAQ section 040008 for details about pitch wheel reinitialization.
Operating System code: Wine Country or New OS!
MIDI or other control protocol:
Software related Links: Multi-trak faq including 6-track conversion template
Patches or knob settings: MT site with archive of both versions of factory sysex
Circuit Overview: below
Scematics/Service Manual:
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors misc
Uncommon chips/modules used:CEM3394 'synth voice', 2 ea.R5106 (Rev. A) OR 1 ea. R5107 (These can be replaced with rebiasing with SAD512 and SAD1024A respectively) Analog delay line(s)
Modifications: Code UPGRADE! and wood ends
General Info Links: Vintage Synth Explorer Hyperreal FAQ

Circuit Overview:
     Uses 6 of the "synth on a chip" CEM3394 with a Z80A processor and a custom IC controlling things. Also a sequencer and arpeggiator. Velecity sensetive. Fairly typical architecture.

Service Tips:
     I've found a few problems with this one. You MUST load factory patches or after you install a new battery, no matter what you program, a weak hashy sound (probably signal bleeding through switching chips) is all you get. This thing apparently performs a check sum and if it's not valid simply ignores you until such data exists.
     But that's not all. I had a bad leak of charge that drained batteries FAST on my first unit I worked on. I repaired that problem but a 260uA leak remained. At the time it didn't occur to me. I figured I'd fixed the problem. But then I got a second one and this one seemed to be fine after battery replacement. had that identical 260uA leak. And I realized..wait. This is too much. When Chip Select is high (within .2V of Vnv) we should see something around tenths of a microamp/chip. Plus some for the chips that run them (74HC02 and 74HC32 plus the MC14022 which is hooked to Vnv also for what reason I do not know. The reset line of that chip..apparently so that it doesn't glitch on bootup.)
     Now, it cost me a lot of pain to find the answer. If you have this problem of early battery death, I want to know about it. Call me at 406-582-5849 or email me. If you see that same current drain let me know because I'd like to establish if this is indeed a design flaw or what. My unit now draws a microamp or thereabouts. Also don't forget to reinitialize wheel, MIDI channels, etc. Search faq above for help there. And also if you power up w/out analog board attached display should count 1-4.

I have lots of parts for these including the R5106 BBD if you have the version with those in it. Let me know if you need anything..I have some switch covers in various colors I think.
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