Just picked up a broken Kawai k3 hybrid synth. Not the most ideal candidate to fix since it’s mostly digital but only paid 100 bucks for it. Guy said it didn’t power and had a burnt cord. Cut open the cord and the burn damage was on the outside not inside so think that was from a space heater or something. Replaced the cord, all PSU voltages are dead on. I turn the switch on, no lights, nobody’s home.
CPU has a good clock, cpu address lines are pulsing, EEPROMs address lines are pulsing, gate array chip that drives the screen and buttons is pulsing, even probing one of the demuxes on the right side and hitting a key on the keyboard I can see it transmitting bits on my scope. Button and screen board has power on components, the logic lines running from the cpu board to the lcd board are pulsing. I noticed the wave forms aren’t pure square, a little bit of modulation on the leading edge But probably normal. The synthesizer board has waveforms all over it, filter chips have power. Forgot to mention all the logic chips on the cpu board have power too, couldn’t find any shorts.
I am not sure where to go from here. As I said it seems the code is executing, yet no lights and display, no sounds. I can only hear a faint pop in the right headphone when powering the synth up. There is voltage on the button board.