After this machine electricity, power indicator light is yellow, press the power switch, indicator light changed from yellow to red, put out after the green light is not bright.
 
After startup, a relay suck up vocalist, explain the microprocessor has a boot instruction, and the grid to the main power supply circuit, according to the indicator light turns green. Judge fault in the main or protection switch power supply circuit.
 
Points by measuring the voltage, judge the fault range, measuring large filter capacitance C818 anode voltage 300 v, boot moment about the suyddenly rising voltage of 320 v, and then relay RL801 disconnect reduced to 0 v, the judgment is mains rectifier switch circuit fault, under the condition of 220 v mains, go doubler rectifier state, cause overvoltage protection circuit starts. Boot, the positive voltage measurement D819 light-emitting diodes (oleds), there are about 1 v suyddenly rising voltage, further judgment is mains rectifier circuit malfunction. For grid rectifier circuit inspection, found that The Times pressure, full-wave rectifier switch circuit IC895 (STR83145LF55) internal short circuit, the circuit, instead of full wave rectifier, troubleshooting.