First for the post u need to see in schematics what does turn on that contactor.....And then check that line from begining... Out of the blue i think some power supply module failure (no screen---nothing) but without the schematics i cant tell (usually the plc (NC ready and NOT Total Stop Line) turn the small contactor then small turn big one )

To examine the contactor
1. U need to have voltmeter
2. While machine is OFF check what voltage is coil of contactor (24V DC or 110V AC or 220V AC)
3. Place the instrument on buzzer or 1k Ohm
4. Measure coil (A1-A2) with buzzer or 1k Ohm--- it should have some resistance ( depends of coil voltage)
5. Turn machine ON
6. Place the instrument on higher voltage than coil ( if 24V DC then on 100-200 V DC, if 110V AC then on 200-600V AC and so on)
7. One man has to try to turn machine ON (procedure... button or .... ) while one is measuring coil voltage
8. Measure the coil voltage A1-A2

If there is a voltage on that coil that is equal (+-10%) to coil voltage of contactor and contactor does NOT turn on then its broken...
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