Oki OKIFAX 5400 Maintenance Manual page 322

E
Line transformer (T1)
This circuit processes send/receive signals required for facsimile transmission, dial
tone receive signals required for automatic dialing, and MF tone send and remote
receive signals. It separates between the line and equipment in terms of DC and also
keeps a balance between the line and the ground.
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 communi-
cation line. Set the switches to "F" for France and "UK" for UK.
40838301TH Rev.1 A3 - 41
UNC/WN5/FN5/DN5