Boot block ic201 (ta7698) using scanning field pulse output pin 24 voltage is 0V, and the field oscillation end 29 feet voltage for normal 2.7-2.8v (with the field sync potentiometer adjustment and change of normal), while the field output tube q301 (a940) be junction for reverse bias voltage up to 1.9V, field output tube q310 (c2073) C is 110V (be junction voltage for normal 0.4V positive bias), push the tube field q302 (2sc1815) of the B voltage is 0V, output voltage of 16V field point (normal value is 27V), replacing the field vibration capacitance is invalid, then check the bootstrap resistor (820 r313 Omega /1w) open, replacement, troubleshooting, repair.5FDservice manual download site