Maintenance records of the control panel of a CNC milling machine

Maintenance records of the control panel of a CNC milling machine

Fault: connect and repair a CNC milling machine after the machine power on the machine control panel of the key indicators are not on, nc system shows emergency stop alarm.

Maintenance: the CNC milling machine is equipped with mitsubishi CNC system M70 and siyang machine control panel.

After the machine is powered on, the LED indicator light on the control panel of the machine tool is not on. Firstly, the power supply of the panel is suspected to be abnormal. Check DC24V power supply in electrical cabinet, normal.

The inspection panel did not find a DC24V power outlet and wiring. Find the DC buck section of the panel circuit board, which has an lm2575-5.0 linear regulator, measure its input end, the voltage is 0V, indicating that the panel is not powered to.

Further check the panel, which is connected with two wide wires, and the other end is connected to the I/O board of the CNC system. There is a fuse next to the I/O board socket. Turn off the power supply of the machine tool, adjust the digital multimeter to the buzzer, connect one meter with the input pin of LM2575, connect the fuse pin of another pen with the buzzer, and see that the multimeter value is close to 0. This circuit is connected, indicating that the panel power supply is coming from I/O board through the line. Measuring fuse, in good condition. The GND line is also connected.

The I/O board also has two other rows coming from the machine cabinet and connected to a small relay board. Check the 24V and GND lines of this section are also connected. Unplug the line, or a multi-pen buzzer, one of the pen to the DC24V terminal, another pen sweep line outlet pin, the buzzer did not ring.

Remove the relay board, the PCB copper foil from the DC24V to the cable socket on the back board has been burned. Welding with a small wire, power test machine, all normal, troubleshooting.

Summary: this fault repair is a running line process, will run the line to repair such a fault. Running the circuit is the basic skill of maintenance electrician.