Varian users who are having the same problem (sometimes "Error E" shows up on the Clinac handpendant) might find the following useful.
The Clinac handpendant sometimes shows "Error E" as the result of a short signal interruption. This happens frequently when the person who operates the pendant moves around while performing "auto-setup" (thereby pressing the pendant's motion enable buttons).
The interruption is usually caused by a non-optimal fit of the cable connector which connects the pendant with the treatment couch via a socket at the base of the couch. The conector has some play in the socket. Even after our sockets were replaced the problem persisted. It seems to be there "by design".
A simple strain relief was constructed.
What you need:
This is the original couch base (a 1996 ETR couch) before the modification:
A small 3 mm hole was drilled into the base of the couch, right above each handpendant socket. The metal is soft, there is no problem drilling:
The spiral cable of the pendant was fastened with a cable tie:
This relieves the strain from the connector. Contact is guaranteed no matter how far the operator moves away from the couch.
The whole procedure takes about two minutes per cable. The costs are practically zero. Since the modification, we never saw "Error E" again ... (patent pending).