Service manual

I-1
Circuit Diagram
RX: 0 V
TX: 5.0 V
RX: 5.0 V
TX: 0 V
NORMAL: 0 V
EMERGENCY MIC: 5.0 V
8.6 V 5.0 V
RX: 5.0 V
TX: 0 V
HOOK OFF: 5.0 V
HOOK ON: 0 V
13.6 V
FRONT-C Unit (VX-4100: Lot. 1~5)