Wednesday 30 June 2021

Maestro OB-1 Octave Box

 Another old octave down circuit with a forest of transistors.... It also have a rare part, MFC-4040 which were a 4.pin divider/flip-flop IC. It went obsoltete in 1975 but according to several sources, NTE754 is a direct replacement. R12 and C21 is marked as "factory tailored component" in the factory schematic so these needs to be socketed and tested. And yes, there is a 1,4uF cap under Q4 but a 1,5uF will do.