I bought a used Yamaha digital piano P-60. It has the following severe issues:

1. All keys and the control buttons don't work randomly. "Not working" means when I press down a key, no sound comes out from the speakers.
2. It's not about any specific key. It happens to random key. Sometimes all keys have no sound.
3. Sometimes the Demo button and Voice button don't work either.
4. Sometimes the voice changes automatically (e.g. from piano sound to organ sound). It's like the Voice button is pressed by a ghost.

Basically this digital piano is unplayable. But it has the following good:

1. It can play demo for hours without any problem. Looks like the main chip is good.
2. Volume control (slider) works well.
3. No key has exceptionally high or low sound.

I am a software engineer and has some arduino experience. I have very little knowledge about circuit board. I had several hypotheses:

1. Hypothesis 1: the power adapter is faulty. I tried another power adapter. No change.
2. Hypothesis 2: there is loose connector. I opened the piano several times but didn't see any loose connector. I unplugged some connectors and plugged them again. No difference.
3. Hypothesis 3: some capacitors are faulty. I didn't see any bulging capacitors. I used an auto-range multi meter to measure some capacitors, but the values did not make sense. Later I knew it's hard to measure on-board capacitor's capacity with the normal multi meter. I searched the internet and watched some videos. I still believe they may be something wrong with the capacitors.

Hope some experts can help me. I will upload some pictures of the PCB. Thanks in advance.

 

Motherboard (?)






A long PCB











Output?







A small PCB for volume control, demo button, voice button.







Some other images

 

Hi, can someone give me some suggestions?

 

hi moniica, I don't have any suggestions for you, but if you still have the keyboard and haven't had any luck, I'd be interested in buying the circuit board from you that you have pictured under "output?"

 

If @moniica is still interested in fixing the keyboard, the first thing I would do is disassemble the keyboard and carefully clean all the key contacts with IPA (isopropyl alcohol).