After examination, Hammond organ, rhythm, timbre pre-emphasis, recording, memory, front double drop, audio power amplifier is normal. Further testing, found the main chip in the keyboard switch matrix 29 fuses have a no voltage (signal) outputs, with an output less than 0.2V. Switch matrix's permutation or not at all, can produce at least one full set keyboard, not audible. Determine is the main chip inside the problem, replace the keyboard back to normal.