The owner wanted to turn this amp into a MKII C+, and luckily for him, it was indeed possible. If he'd purchased a version with reverb, I wouldn't have been able to do the conversion.
I modified the preamp to exactly match the MKII C+, which involved: improving the FX loop circuitry, employing the unused (reverb) triode as an additional lead stage, completely changing what the relay and push-pull pots switched, a LOT of trace cutting, re-routing, and component swaps. Trying to find the room to do this and install all the additional tone filter circuits was a real challenge, but it turned out well! The FX loop actually sounds good now, and the lead channel is liquid smooth.
Since the amp was made in 1980, I also replaced all the power supply capacitors.
