After the test, according to press the power switch after absorbing the relay of the chorus, without light is changed from yellow to red to green, then issue the relay disconnect. After startup, a relay suck up vocalist, explain the microprocessor has a boot instruction, and the grid to the main power supply circuit, the light is changed from yellow to red and cannot become green, judge the fault in the main switch power supply circuit, there is no 12 v voltage output. 2mcservice manual download site
 2mcservice manual download site
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 malfunction. 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), have suyddenly rising voltage, further judgment is mains rectifier circuit malfunction. For grid rectifier circuit inspection, found that The Times, full-wave rectifier switch circuit Q801 short circuit. After the Q801 demolished, instead of full wave rectifier, troubleshooting.2mcservice manual download site