Sony PCS-1500 Service Manual page 145

4-1. Check Items Before Starting Self-diagnostics
Locating the trouble whether it is in IF-745 board or in the PCS-1500/1500P system
S-11
PCS-1500/1500P
NO
works when the IF-745 board
is replaced
YES
The LINE I/F
NO
menu of the dial setup
Replace the IF-745 board
contains V.35
YES
IC755, IC754 and their peripheral
BRI-2
4-15
PCS-1500/1500P