The Electric Piano Forum

Repairs, Maintenance & Upgrades => Parts, Service, Maintenance & Repairs => Topic started by: memcdowell1s on April 13, 2021, 11:47:51 AM

Title: Hello, new here - Yamaha CP-70B repair project
Post by: memcdowell1s on April 13, 2021, 11:47:51 AM
Hello all, just joined the forum. It seems like this is the only place on the web where the Yamaha CP70/80 are discussed, so here I am.

I just purchased a CP-70B. I've had a few classic synths and organs in the past, but I always liked the tone of these and finally found one within driving distance. Unfortunately, it wasn't complete and working like it was described to me.

First, the "power supply" included with it wasn't correct, or even compatible with a CP, so I couldn't test before purchase. I have the proper Cannon jack on order and will wire up a proper supply. 18VDC/200mah sound about right?

Next, when I rigged up a temporary power supply, I found that no current was getting to the power board. The red power LED light is shorted; does anybody know what might fit as a direct replacement?

Once I bypassed the light, I found that one of the voltages was missing. The power board has a big crack down the middle. I wired a jumper across the crack and got all three voltages working, but does anyone have a source for those boards in case this one gets worse?

Finally, after all that, there's still no output  :-[. The electronics are completely silent. Does anyone have any experience with these preamps? I haven't dove into troubleshooting, besides making sure the piezo output and main output jacks have good connections to the board.


Thankfully, the mechanical parts are pretty decent. The action seems okay, and I was able to roughly tune it. It's missing a leg brace and the sustain rod, but at least the legs and pedal are there. I didn't want another project, but these are pretty thin on the ground where I am.

Thanks, all!