Boot, through inspection, pipe Q551 sc5591000lk (2) short circuit, can change after boot, appear white, no picture, there is interference upper line, sometimes don't boot, burn manager sometimes turned on. JrHservice manual download site
According to preliminary judgment fault phenomenon following circuit has a problem 1, 2, 3 line scan circuit, power circuit circuit JrHservice manual download site
First measured the output voltage of the power: + B shows no problem with the power supply circuit. Then check that the line scan circuit and apparent, found when measuring apparent put power supply voltage of 260 v, 200 v is much larger than normal. Measuring line output transformer and other sets of voltage output, are higher than normal voltage. Doubt caused by horizontal frequency is too high. Measure the line scan circuit of power supply, to much. Control circuit diagram, 5 v voltage by IC2706 voltage, measuring normal IC2706 1 foot 15 v input, the output voltage is on the high side. Doubt IC2706 bad earth. Measuring grounding IC2706 foot 3 between foot and ground, proved right. Control circuit board check, found that external IC2706 3 feet jump line JSA28 open circuit. Replace the rear view put resume normal voltage 200 v, machine back to normal, also replace Q551 JSA2. JrHservice manual download site
In maintenance the machine found fault phenomenon is not fixed, sometimes boot, appear the phenomenon. Sometimes boot protection, light is flashing. Sometimes boot instantaneous burn pipe. By measuring the DG plate of 5 v power supply, 37, 38 feet boot instantly when the foot is no voltage, boot will burn pipe in a minute. Boot have voltage, wouldn't burn pipe. In measuring voltage time is shorter, so do not electricity for a long period of time so as not to cause unnecessary losses.JrHservice manual download site