Code B140, Phone System Fault

The BCM receives phone status information directly from the phone transceiver and from CRT controller across serial data line. The phone status input to BCM is a pulse width modulated signal that indicates the state of the phone (see BCM data parameter BD45). The phone status input from the CRT controller is a discrete indication of whether CRT is able to communicate with the phone transceiver across "E" & "C" data line.

Code B140 will set if either of the following sets of conditions are met for more than 2 seconds:

• Code B335 is not set
• CRT controller indicates a phone communication failure

Code B140 will also set if phone status input, BD45 is 7, indicating zero percent pulse width signal (a ground).

Fig 1: Code B140, Schematic, Phone System Fault