February 2012 23 – 369
23.3 Possible error causes
îš„ Heavy contamination --> Key functions may be impaired.
îš„ Jammed chips --> Key gets stuck.
îš„ Pressure contact defective. --> Key no longer reports actuation.
îš„ Liquid has penetrated
îš„ Defective keyboard PCB
îš„ Defective ribbon cable between screen and keyboard (screen soft keys)
îš„ Defective ribbon cable between keyboard and machine operating panel (potentiometer)
îš„ Defective USB cable between keyboard and MC 6222 or BF 250
îš„ Potentiometer wiper worn
îš„ Defective touchpad
îš„ Interface of a control component defective
Defective keys either do not contact any more or are in permanent contact.