Tested found IC851 damage, and damage to IC851 because D very sharp Yi absorbing circuit R, C numerical inappropriate. R873 original resistance is 470 euro, resistance is too large, the peak absorption is too weak, should be changed to 4, 7, R886 value is 100 k, resistance is too large, poor absorption peak, change a little for 12 k. After the above changes, rush absorbing circuit works well and can very good protection IC851 inside the switch tube.hdZservice manual download site