From: peterwieck33@gmail.com   
      
   Thank you!   
      
   > ** Should be digit date codes ( week and year) on the filter electros and   
   output transistors.    
      
   This, I can check.   
      
   > This is the later version ( no ICs) sold from 1980 onwards.     
      
   I would have thought the same, but it lacks the internal fuses on the 12V   
   power-supply, and the primary fuses are internal. This mirrors the original   
   schematic (power-supplies), but for no ICs.    
      
   Per Orion Blue Book (not the most accurate):     
      
   citation 16 1976-1979 - Some overlap with the 16a, apprently. ICs stopped   
   somewhere in production.    
   citation 16a 1978-1979 - slightly derated, no ICs.   
   citation 16as 1978-1979 -  no LEDs, no ICs.   
   citation 17 1977-1979   
   citation 17s 1975-1979   
   citation 18 1977-1979   
   citation 19 1977-1979   
       
   The earliest photos I could find showed the fuses accessible externally,   
   directly under the speaker jacks, either side of the power cord. So, given all   
   this, I am trying to find someone who has an idea of that serial number. All   
   others I could find (   
   pictures) were straight numerics, no letters. But for one that was   
   hand-written, and clearly a test-bed unit (with the external fuses,   
   however).   And, I also keep one-each 17, 18, 19 all with conventional S/Ns   
   and reflect their respective OEM schematics    
   accurately.    
      
   Peter Wieck   
   Melrose Park, PA   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)