From the failure phenomenon, without screen is commonly fluorescent display LCD part, no filament voltage or plus the control voltage is not in place. Check CON01 AC220V input, control transformer secondary filament voltage of 2.4 V AC is normal, and are negative voltage, anode voltage measurement show that no driver level input, circuit IC1 (HD40316B38S)} {21 feet a + 5 V voltage, {8}, {9} feet clock oscillation voltage of 2.8 V, 2.1 V, respectively is normal also, specify between driving circuit and CPU circuit, if only drive circuit fault will only make a stroke segments in display abnormal. Check IC1 emphatically {and} feet and IC2 {4} feet voltage, circuit IC2 (SWM002) in the CPU, which {4}, {7} to {12} feet are controlled by CPU, as IC2 {4} feet no voltage input (the normal voltage should be 3.5 V), when a check is connected with the IC1 {and} feet, it found that the foot has a virtual welding, repair welding processing after the voltage is normal, troubleshooting.ygkservice manual download site