And set the brightness and contrast to the largest, there are lack of the brightness of the color image; Sprite brightness slightly higher than the main screen, but still significantly darker, and a transverse interference light line, the main screen field amplitude slightly compressed, and audio and other functions are normal 2frservice manual download site
 2frservice manual download site
Preliminary judgment fault for ABL circuit control or brightness signal loss caused. Chad R plate (panel) on Q1867, both areas Q1866 conduction state, so not accused of ABL circuits; Due to the main, Sprite or dark, luminance brightness loss point should be in the public channel. Native M18M machine, equipped with many quality improvement circuit, so the available signal when maintenance short-circuit method to determine the relevant function board. Unplug Y board (comb filter plate), with 0.1 u F capacitance sub motherboard A42 sockets and A43 socket {1} {2} feet feet, switch on the main screen black screen, Sprite is still dim image; Y back plate, remove the M board (dynamic sharpness correction board), still use 0.1 u F capacitance sub the A13 motherboard socket {7} {8} feet and A15 socket, boot failure phenomenon is not changed. Determine the fault point in Y board and M board motherboard after signal process, focusing on IC601 (TA1215AN) and auxiliary circuit. Measured brightness signal processing related pin to low voltage value are more, analysis is caused by insufficient power supply voltage. The two sets of power supply, 12 V is normal, and 9 V voltage is only 6.4 V. Along the line check to get the line D board, 9 v voltage circuit such as the appended drawings. Switching power supply output pulse voltage transformer secondary S3 foot after rectifying filtering for 14 V, then through L845 filtering, R842 current-limiting followed by IC805 (AN7809) {1} feet, measuring IC805 {1} feet just 7.2 V voltage, then measuring C836 voltage on both ends of 14 V is normal. Shutdown removed its resistance to 28 Ω R842 test, and figure coordinate values of 2.7 Ω (3 w), causes IC805 output voltage drop, IC601 brightness inside channel gain, and cause the light from the darkness; Impact due to lack of 9 v power supply again concerned in the IC circuit, the scene picture compression phenomenon. Will R842 replacement after the image back to normal.

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