Guangyang PLC maintenance Maintenance model: DL350 Failure phenomenon: customer self reported that the output point of the device is always on the power after the device Fault analysis: the PLC transistor output, the power not connected directly without measuring the resistance between the output and the 24V is infinite, is the normal state, PLC is connected to the power supply, the output resistance measurement of Q1 and 24V value of 0, to observe the output point corresponding to the indicator light is not bright. Cut off the power supply, open the PLC shell, remove the CPU PLC board, the power supply is switched on, the transistor Q2 corresponding measured output point to have the conditions to conduction conduction, the transistor driver chip IC turn-on trigger, the chip for isolation and power amplifier, the input driver for DC 5V, the external output voltage of DC24V measure voltage between IC chip output terminal and the Y1 side of the public DC 22V (DC 0V when the output voltage is not normal) between the public terminal measurement chip and IC input output directly to the opposite foot is DC 0V (not lost When a normal DC 0V), indicating that IC has been damaged, the chip for the SMD, need to be replaced with air gun, after the replacement of power output test, normal, download the test program, PLC to do a comprehensive test, all the normal, PLC repair. Jiahong Weike fault to solve Koyo PLC: power indicator light does not shine, the output has no output, input control, program error, confusion, not communication, no output, no input module; please dial service hotline 0755-28916839, 13640994287, we have professional customer service staff to quickly respond to your needs. Jia Hong Wei repair service hotline: 0755-28916839, 13640994287 Shaw