Yamaha C-85 RCA upgrade I completed the upgrade of the RCA terminals on my C-85. It's not that hard but very time consuming. The original terminals are the weak link on these early Yamaha Preamps IMHO. If you use tight interconnects you can pull the original terminal ground sleeves off in a snap. I have also seen these get loose over time and even standard interconnects will cut out if you wiggle them. This is a great upgrade modification and this C-85 sounds very solid now. You have to slightly drill out some of the holes in the PCB for the wire to replace the original bracket mount. I used AWG 21 cast copper wire. It is important to ground it just like the stock setup. You will also need to run a new ground to the rear plate and the PCB. These RCA locations are very close together but there is still room for most RCA interconnects. Depending on the terminals you are using, the isolation washers need to be trimmed very slightly. Next will be my C-2X but I will be using even better terminals and wire on that modification. It is basically the same setup as the C-85.