Judgment is on / off control circuit failure. Of the circuit, it was discovered in the on / off control circuit of Q841 and the optical coupler is extremely I) 841 of a corresponding pin ② ① a voltage change, ③ - ④ pin but no voltage change, thereby judgment D841 internal open, so that the shutdown signal is interrupted. Although the microprocessor has issued a shutdown signal, the image is no longer under their control no sound, but has not received a shutdown signal switching power supply, still the output voltage, resulting line scan circuit continues to operate, there grating. After replacing the D841, troubleshooting.e4gservice manual download site