Boot relevant brightness signal processing circuit, measuring nq501 (ta8783n) of the light signal input pin 59 voltage for normal 3.6V, color transient processing circuit block nqt01 (ta8814n) 15, pin 2 voltage, black stretch circuit nqe02 (cx20125) and voltage are normal, then the fault range reduced to brightness processing board, remove the brightness processing board, found that the brightness acuity strengthening integrated circuit block dql10 (an5342k) pin is a repair welding, welded again again, check the board and other components of normal, (the board uses smaller components surface mounted, inconvenient repair) to reload the motherboard, the fault is still remains. Then according to this principle, the direct use of 4.7u/50v capacitor connected across the board to the brightness processing board video signal input, output plugin for xtl1a 1, 3 end, and from the input to the 1 terminal brightness boards xpl1a. After such a treatment, the fault is no longer present, repair.6LVservice manual download site