The cause of the problem may be needed for the backlight power amplifier 30 v working voltage abnormal, or over voltage detection circuit has a problem. The over voltage detection circuit, as shown in the figure below is made up of Q7750 ~ Q7753 and peripheral components. In the second boot instantaneously, measured Q7750 base voltage of about 0.7 V, suggests that overvoltage protection circuit has accused. : the original, should be 30 v power supply malfunction, or 30 v voltage over voltage detection circuit is defective. Will Q7750 disconnect, when the second boot measured 30 v voltage is normal, so the over voltage detection circuit has a problem. Check each element in the figure, find Q7751 damaged, switch to a model for a 2 sc2001sol triode, troubleshooting.BUuservice manual download site