[sdiy] Moog 903 schematic

[Terry Michaels]

Message text written by "Steve Ridley"
>> I recently scanned and edited the schematic diagram for the Moog 903
white
> sound source. 

Terry
        Do you have any other Moog schematics from that period?  
I have a modular which includes some 1967 oscillators and a few 
later modules, and they're different from the schematics in the
Norlin book.  I'm looking for the 901, 901A, 901B and 901D
schematics from around that time.  Any leads would be appreciated.


Thanks


Steve Ridley<

Hi Steve:

I have nearly every early Moog schematic, however they vary greatly in
quality, some are very good, and some are very hard to read copies of
copies.  The 901had a 901A circuit board and a 901B circuit board mounted
behind one panel, with (I think) four extra panel pots for adjusting each
of the waveform output levels.  The earliest schematic of the 901A that I
have, drawing number 1100 dated 7-22-66 used two series strings of silicon
rectifiers for the exponential converter, this drawing carries the
statement "Supercedes drawing number 1069", so there may be an even earlier
version of the 901A.  The later version of the 901A (same as the schematic
in the Norlin manual) used two CA3019 diode arrays for the expo conversion,
and had a different circuit board layout.   The later version also
eliminated the "mid high compensation" trim pot.  The schematic for the
later version was completely redrawn, but used the same drawing number as
the earlier version, 1100.  

The earliest 901B schematic I have, drawing number 1101 dated 7-25-66,
carries the statement "Supercedes drawing number 1072", so there may be an
earlier version of that one also.  This schematic was completely redrawn
dated 6-13-69 but used the same drawing number, and had some minor circuit
changes.  The 6-13-69 drawing is used in the Norlin manual.

I don't have a schematic for the 901D, it is listed in the Moog 1967
catalog as a Variable Waveform Output Stage.  According to an earlier post
by Roger Luther, only eight 901D modules were manufactured.

Terry Michaels