Yamaha PM-430: overhaul and and a luxury direct out modification

This Yamaha PM-430 mixing console has extensively been repaired, cleaned, recapped and modified by Vintage Audio Sweden. The customer’s wish was to implement transformer balanced Direct Outputs on all the eight input channels, according to the technology used in the 1970ties. Together we decided to continue with installing eight API Active Combining Amplifier clones supplied by @capigear All the ACA amplifiers contain a 2520 Discrete Operational Amplifier clone by @capigear which drive an Ed Anderson clone of the API 2623 output transformer, most frequently used by API with those ACA boards. It was necessary to design a new circuit board with Balanced Output Attenuator switches together with a Power Supply circuit board to supply clean, dual rail 15Vdc to the ACA amplifiers. The direct outputs are connected to a Tascam wired DB25 female connector on the back. All the signal wiring installed (balanced and unbalanced) is shielded and the components of this modification are carefully selected following the technology of that era. For the sake of completeness I will supply a copy of the original Yamaha PM-430 Service Manual, together with a copy of the schematics of the modification. Everything has been attended to. All the switches and potentiometers have been cleaned an lubricated. All the boards have been checked for bad or cold solder joints. All the electrolytic capacitors have been replaced with carefully selected, high temperature substitutes. The metering is recalibrated to factory specs. While working through the console, replacing all the electrolytic capacitors, a few quirks and faults came to light, which needed attention and repair. Creativity was needed to solve all the problems since several parts are no longer available.