Code B140, Phone System Fault

Fig 1: Code B140, Wiring Diagram (1 of 2) Phone System Fault

Fig 2: Code B140, Wiring Diagram (2 of 2) Phone System Fault

The BCM receives phone status information directly from the phone transceiver on circuit No. 902 and from CRT controller across serial data line. The phone status input to BCM is a pulse width modulated signal that indicates what state the phone is in. 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.

Or phone status input, BD45 is 7, indicating zero percent pulse width signal (a ground).