1. The Out of Stock Limit Switch is activated.
Action – Check to see that the Out of Stock Limit Switch is not closed.
2. There is a short circuit in one of the 24v dc devices (Length Encoder, Feed Rate Encoder, Angle Encoder or Proximity Sensor Switch or the associated cables for these two devices) on the machine.
Action – To find the fault, disconnect the wires that supply power to the devices. These wires take 24v dc power from two terminals located on the input side of the Mitsubishi PLC control. The terminals are labeled as 24v and S/S. Disconnect the wires, then start the saw and ensure that the hydraulic circuit stays “latched”. At that point turn the power off then reattach one of the two wires, then start the saw again. In this manner we will located the faulty circuit. Once the faulty circuit has been found then they can use the information in Section 3 of their Operations and Maintenance Manual to troubleshoot the problem.
3. If disconnecting the wires as noted in number 2 above does not resolve the problem.
Action – Check for an active LED input at the status indicator LED’s found on the top of the PLC. Particularly we are interested in the BATTERY ALARM LED’s and the PROG-E / CPU-E alarm LED’s. If the PROG-E / CPU-E alarm LED is flashing this means that the program in the PLC is corrupted. If the LED is not flashing, but is lit and steady then there has been a CPU fault, this means that there is a hardware problem in the PLC control and it would need to be replaced.
4. Check that output Y0 led is lit when pushing the Hydraulic start pushbutton. Check that wire 1M7B (wire number varies) is connected properly at Y0 terminal of the PLC. If no improvement is noted disconnect wire 1M7B(wire number varies) from the Y0 terminal and measure voltage from the Y0 terminal to Neutral terminal. DO NOT check with wire attached to Y0 as the connected wire will backfeed voltage to the Y0 terminal. If no voltage is found PLC output Y0 is defective. Check Fuse 5FU1, if fuse condition is good and proper voltage is measured record all input and output leds’ found lit on the PLC control when hydraulic start push button is pushed and contact HYDMECH’s service department (877) 276-7297.
If voltage is present at Y0 check reconnect wire 1M7D (wire number varies) to Y0 and check that the other end of wire 1M7D (wire number varies) is properly connected to H1 terminal. Check voltage thru H1 terminal to wire 1M7B (wire number varies) thru to terminal A1 of the hydraulic motor contactor.
At the NO contract on 1M contactor
-check that wires are tight
5. Check between terminals L and N on the input side of the plc. If voltage is present and no LED’s are lit then the PLC is defective and will need to be replaced.
Posted in: Troubleshooting