Check the CPU d701 (ch04001) characters, pin, oscillation, voltage for normal 5.0V, 25 foot line pulse voltage is 4.9v, normal, and 26 foot field pulse voltage is 0.4V (normal 4.2V), indicating that the pulse circuit failure, check the substitution and related components, had no effect; come back to check for a pulse circuit, the contemporary change capacitance c761 (1000p), character appears, the capacity for the 0 basic, replaced with a 10N ceramic capacitor, repair. The trouble is, the special field pulse voltage normal but wrong, wrong is normal.z46service manual download site