Hi, not a common keyboard but hopefully someone can help…
My 1981 Yamaha CP25 electric piano (analog synth, really) has two jack outputs. One is intermittent. I’m trying to find the fault in the circuitry with little experience and a can of electrical contact cleaner spray.
The service manual block diagram shows that most of the circuitry is mono until the main volume. It then separates into two signals, goes through the tremolo (which, when turned on, modulates each signal in opposite polarity to create a stereo panning effect), then automatic muting on startup and a line on/off switch that turns off the signal to the outputs (for headphone-only use when plugged into amplification).
I can locate these parts of the circuitry, but am unsure whether I should be spraying, looking for dry solder or something else…
Output 1 seems to be intermittent with either no signal, very low or normal volume. It’s hard to tell if sending a high volume through it helps open it up or not. Seems to help sometimes.
Any help appreciated.
Steve