The input unit is usually the monitor of faults and will not allow the control power on to troubleshoot, but I have used this method in the past on that input unit A14B-0076-B00
Some input units also have a door interlock that is sometimes wired to the Main cabinet disconnect interlock, so if this is open it won't allow the control power to come on.
On this unit I have also jumpered out the alarm relay contacts to allow the control to come on so that further trouble shooting can be done.
There are two pins that are labeled P1 & P2 that are the Alarm relay contacts , this usually brings in RY1 and allows further trouble shooting, also test all the power supply unit voltages, usually there is a set of pins on the main board next to the power supply for checking.
Al
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.