Instant boot sound high pressure created, and then three non-measuring Q841 and Q554 base has O. 7V voltage protection circuit is determined.ifWservice manual download site

     Unprotect method using overhaul. Disconnect the line output circuit, connected to dummy load, short circuit STAND-BY, and then turn the main power still does not start, proved to be the protection of the power supply circuit board caused. Q554 base before turning off the output voltage of the switching power supply is normal, indicating a protection circuit failure caused by false starts. Measuring a, b, c, efg test point voltage, c-point high voltage 4.5V, the overvoltage protection circuit to determine the fault. The detection circuit, voltage divider resistors R868 has found open welding phenomenon, resulting in R868 upper voltage increases, the overvoltage detection circuit starts strayed protection status occurs three noes. After welding R868, back to normal.ifWservice manual download site