First off keying plate three locks, cutting down the front panel circuit board on the back up with digital multimeter test. The board has seven key switch, a remote control receiving/zoom box IR1701 and some switching diode. Measuring IR1701 {2} feet VCC only 3 v, 5 v large difference in the normal, is likely to be caused by the voltage drop system microprocessor control circuit can not work normally. Through inspection, the failure is due to QF0901 open, QF0901 + 13.78 V voltage by R, after open D458 b and e output 3 V voltage. QF0901 appearance such as small encapsulation triode, have insurance effect in the circuit, with 0.5 Ω insurance / 2 w resistor instead of after processing power, the screen brightness returned to normal. Packed the whole machine remote control and panel keying after heart back to normal.MNNservice manual download site