Oki B4100 - Manual (Page 453)

40055101TH Rev.4 453 /
F Off-hook detectors (IC2, RL7)
These circuits detect the off-hook state of the telephone connected to the TEL1, TEL2,
through LINE terminals. IC2 uses a high detection sensitivity than of RL7. In TEL/FAX
mode, the higher sensitive IC2 is used to detect the off-hook state of the telephone while the
main equipment is hunting a line.
Usually, IC2 is short-circuited by the CML relay (7) in the standby state and RL7 is used
for off-hook detection.
G Impedance switches (S5-1 to 5-2)
These circuits set the impedance according to the line requirement.
S5-1: 370 ohm + 620 ohm//310 nF (UK)
S5-2: 600 ohm (F)
H DC resistance switches (CN26 and CN36)
These switches set the DC resistance according to the line requirement.
Q FICC (IC6)
This circuits reduces the DC resistance to increase the loop current momentarily to assure
operation of the switch at line seizuring.
R Constant current circuits (Q1 and Q2)
These circuits provide DC characteristics according to the French line requirement.
S Shunt (RL5)
This circuit prevents bell resonances in the telephone sets connected in parallel during pulse
dialing and also reduces distortions of the pulse waveform.
T Communication line terminal switches (CN26 and CN36)
Unlike other countries, pines 2 and 5 are connected to the line for the UK communication
line. Set the switches to “F” for France and “UK” for UK.