Transformer Circuit; On Hook State; Off Hook State - Xerox WorkCentre PE120 Service Manual

Product Summary

4.8.4 Transformer Circuit

The Transformer circuit is a line impedance matching circuit which matches the internal impedance of the
fax machine to the external -48Volt DC impedance of the PSTN system.
The Transformer circuit insolates the fax machine electrically from the PSTN.

4.8.5 On Hook State

DC10V ~ DC100V, DC Resistance: 5M. and over
DC150V ~ DC200V, DC Resistanc : 30K. and over
Ring Sensitivity
Ring detection voltage: 40Vrms ~ 150Vrms
Ring detection frequency: 15.3Hz ~ 68Hz
Ring detection current: 20mA ~ 100mA
Pseudo Ring Sound
Ring frequency: 750Hz + 1020Hz
Ring Interrupt period: Mark/Space controlled by CPU/Modem

4.8.6 Off Hook State

DC Resistance
DP Dial Mode (DC 30mA) : 50 ~ 220 .
DTMF Dial Mode (DC 20mA) : 50 ~ 300 .
DTMF Dialing (DC 20mA) : 50 ~ 540 .
Matching (Input AC Impedance): 600 .±30% for 300Hz ~ 3.4KHz
Minimum Line Current detecting Off Hook:
20mA (Handset Hook Off)
15mA (External Handset Hook Off)
Minimum Line Current for DP Dial transmission: 20mA ~ 120mA, Product Margin : 20mA and over
4-22 WorkCentre PE 120/120i