I have installed two LCD displays for ABB PLC PM671, they were working fine, but suddenly one of them stopped working and shown fault, that caused stopped working other instruments connected through same power supply. I removed the power connector, all the other instruments working instantly. when I took faulty lcd to lab for repair, it starts normally, and no dysfunction was shown. I brought it back for plugging it shows same error again. I have replaced power plug, power cable, but same position.
What is the fault?