Line Path Switching Control Circuit - Toshiba DP120F Service Manual

4.1 Line Path Switching Control Circuit

US/CA/TW models
The line path switching control circuit consists of the CML relay (RLY2) and analog switch
(IC51) on the NCU PBA, the I/OP-1 GA (IC7) on the Main PBA, and other peripheral devices.
The CML relay is switched according to the CML1 signal output from the I/OP-1 GA on the Main
PBA. When the CML1 signal goes HIGH, Q51 turns on to turn on the CML relay.
The analog switch is switched according to the CML1 signal and ATT3DB1 signal. When the
CML1 signal or ATT3DB1 signal goes HIGH, the analog switch turns on.
Turning on the CML relay and analog switch allows the MODEM to be connected to the line.
Signal Name Type
CML1 O
ATT3DB1 O
March 2000 © TOSHIBA TEC
Fig. 7-4-3
Active
H Line 1 CML Relay Control Signal
H Line 1 Attenuator Control Signal
Description
7-79
Destination
RLY2, IC51
IC51
DP120F/DP125F Circuit Description
07-04-01