Watkins (WEM) Copicat IC300
...yes, I know it's not from the sixties
This version of the Copicat was the first to make use of integrated circuits (ICs) instead of discreet transistors for the majority of the signal processing. (27/04/2016: apparently not. Update later)
The device chosen by WEM, in common with most manufacturers at the time, was the 741 operational amplifier in an 8 pin dual-in-line (DIL) package. Life for the service technician was made easier by the reduction in the component count and also by the use of sockets for the active components.
The Copicat IC300 upstaged it’s predecessors by providing four inputs for microphones or instruments instead of the usual two. Forming what was in effect a small mixer, it could handle, for instance, all of the vocals for a small band or provide a mixture of instrument and vocal processing for a single performer.
1) Copicat IC300 Schematic
This is what's in my own unit. There's no sign of a serial number anywhere and, speaking to another owner (Hi Artur), they don't appear to have had any.
No guarantees that it's 100% accurate, so check out the other schematics on the internet, including the genuine WEM drawing. Component numbers don't appear on the originals so I've invented some to make life easier (as you do).
A couple of points to watch before sticking your hands in....
# Although the factory drawing (issue 1, dated 1979) shows a mains earth connection, this particular unit still doesn't have one. Be careful.
# The fuseholder comes before the mains switch, so be sure to unplug the mains cable before changing the fuse (but you knew that anyway).
The 'Send- Return' system is fine for an amplifier but not that useful if your using it in a mixer effects loop. It doesn't block the straight through signal. Input sensitivity in this mode is set by the Input 4 gain pot. That's not obvious from the panel markings but at least it's the one next to the socket.
2) Copicat IC300 Main Board
3) Copicat IC300 Bias Oscillator and Rectifier Boards