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I purchased a second hand Yamaha CP73. It was working fine for a while.
Five keys stopped working in the upper two octaves this morning. It was working yesterday. It was not moved overnight.
I tried a factory rest, but it did not fix the issue.
Are there any fixes I can try? Does anyone know how to access the keybed? I have reached out to Yamaha, but would like to try basic fixes to avoid service fees if possible.
If you're able to find the Service Manual for the CP73/CP88, it will have all the details, including disassembly instructions and parts descriptions. I don't know this particular model, but I would assume the keybed is accessible from the bottom. If you prop the instrument up on pillows or similar, you can safely turn it upside down to remove the bottom cover.
The keybed itself typically consists of several sections, that are connected with ribbon cables. If the connectors become loose or corroded, this type of problem can occur, so check those out if you can.
I thought I would post an update. The top three D#/Eb keys did not work and the top two A keys did not work.
Unfortunately I could not find a service manual online.
I took the two side panels off.
I removed the screws on the back of the CP73 that fix the top panel to the bottom panel.
I was not able to remove the top panel. I could jiggle it a little, but I did not want to force it.
I think some of the knobs/display for the Sub voice (particularly the Voice Category Selector knob) are connected to an internal chassis that is mounted to the bottom panel. I did not want to disassemble it any further because I did not want to break something, or forget how to reassemble it.
I reassembled it and all of the keys worked. Maybe there was some dust, or something else somewhere it shouldn't have been and I dislodged it while moving it around and loosening some parts.
There are other possible explanations, but same keys in different octaves failing can be caused by a single wire losing contact (in the keybed section interconnects, each line is usually shared by two keys). I'm guessing that the physical handling was enough to restore contact, but that could be temporary.
I was unable to find the service manual too, but you may be right about the assembly. I would be surprised if the instrument couldn't be opened, but better safe than sorry.
Unfortunately the issue has returned. I found a video which shows how to remove the top of a Yamaha YC61:
The Yamaha CP73 Is the same. There is a metal support holding the top and bottom panel together. The support is connected to the bottom panel with two screws.
I will need to unscrew the keybed from the bottom panel before I can access the keybed. I plan to check connections and give it a clean. I will make some enquiries with repairers in the meantime.
I have reached out to Yamaha for a service manual too.
Please let me know if you have fixed a similar issue.
Thank you, zacintosh13. That is helpful. Were you able to find out any more information?
Were you able to successfully open the CP88 using the instructions from the video you posted?
I started the process but I got nervous and put everything back together. One thing I noticed right away is I couldn't tell what kind of screw head was used. I was able to remove them with a T10 torx bit but whatever those screws are, it is a little larger than a T10 (but smaller than a T15).
