Most good techs could take care of this for you. If you do the tech legwork, it will save you bench fees, since most charge by the hour.
You need the schematic and wiring diagram for the cable which goes between the power supply and the console. Then a decision needs to be made. Do you need to unplug the power supply from the board?
It is usually cheaper to hardwire the components together and often the connectors which were used 20+ years ago may not be in common use today.
Both David Kulka (an independent studio tech in LA) and Jim Williams (well known for his modifications to existing audio equipment) are active in this forum, capable of doing a job like this, and are based in Southern California.
I can't speak for what the charge for this job would be by any tech. I don't know if you would save money over ordering the cable from Yamaha. Good luck!
Galil