Check fuse F801 (3.15A) has blown , power thick block IC802 (STR-S6307) 1,2,3 feet ( ie internal switch C, E, B -pole ) has breakdown , after welding under its periphery will IC802 components , it was discovered regulator control tube Q801 breakdown of each pole are other no abnormal suspected adverse Q801 damage caused IC02 damage. Optional power larger A966 substitution Q801, the IC802 new ones, in order to prevent accidental turn -line load is disconnected, access 60W bulb false load test machine , when just machines to monitor the mains voltage is 140V normal, but about 10 seconds after the lamp goes out , check the fuse has blown , IC802 internal switch and the breakdown of each pole , and new for the A966 was not damaged. Further examination found that charging resistor R829 (2Ω) has been blown , what causes burnout has become the key to R829 for failure. R829 and -9V power supply filter capacitor C843, C813 positive and C810 (1200pF/2KV) connected to one end while the other end IC802 C810 1 foot 300V power supply that end , the end of the work when the switch will generate a kilovolt power supply voltage spikes , be absorbed by C810 . Thus suspected adverse C810, the C810 welding inspection, has indeed leak shorted. After observation, the nominal pressure value on the C810 only 1KV, while the icon is 2KV, it is clear for the lack of pressure caused by the breakdown leakage . The R829, C810, IC802 to replace , start measuring the output voltage of 140V main power supply is normal, continuous test machine without exception , remove the dummy load line access load test machine , troubleshooting.tU9service manual download site