Found R7085 open check, change again after a burn out. So check again and IC7109 Q501 and 18 V power supply branch, but still not found the problem. Use substitution method to replace the IC451 and IC7001 IC7002 and peripheral components, only measure Q451 and D454 is damaged, replace after the fault has yet to rule out, measured by the voltage measurement method after IC7105 1, 14 feet voltage is 3 V, voltage of 0.7 V, 7 feet IC7106 1,7,8,14 feet are - 3 V, through the analysis, the voltage should be not normal, can cause excessive current IC7001 and IC7002 and burn out R7085, so in a static analysis. According to the general maintenance field circuit and convergence circuit fault occurs when the general line circuit will work in an instant and protection, but this machine didn't work, so on the voltage measurement method, the voltage measured DG plate of the foot, found for DG board 5 V voltage to 0.8 V, and high temperature IC2706. By using the open method to exclude IC2706 for the components one by one, when out to IC7107 5 V voltage return to normal. After replacing IC7107 troubleshooting. gLjservice manual download site
Conclusion: because of substituted IC451 do damage, from IC451 and IC7107. Damage caused should be IC451 IC7107 synchronous pulse voltage is too high and damage.gLjservice manual download site