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Telemecanique TSX17.20 CPU fault

Telemecanique TSX17.20 CPU fault

Telemecanique TSX17.20 CPU fault


I'm having problems with an old 1989 NUM TSX 17.20 plc which runs on one of our older CNC lathes (Somab Transmab 400).
Basically the main 3-phase contactor is not being energised by the PLC. The trigger circuit for the contactor goes through numerous safety switches and numerous relays. We've been through the circuitry and everything is as it should be.

The problem lies with the NUM 1720 plc. For some reason it is not in run mode and the CPU fault light is on. The two expansion boards both have their I/O lights on too. The PLC is getting voltage and is earthing correctly from what I can tell.

Does anyone have any experience with these old controllers? If so can anyone point me in the right direction?

Installation / manuals for the TSX1720 @

Many thanks,

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