Oki OKIOFFICE 84 Service Manual page 429

21 Telephone cascade/parallel switches (S1-1 to S1-2)
To connect the telephone connected to the TEL1 terminal and an external trephone in parallel, set the switches to
ON.
22 16 kHz LPF (L7, L8, C7, C507, C9)
This low-pass filter removes 16 kHz metering pulses.
23 Transmitter amplifier (IC501 1/2)
This transmitter buffer amplifier amplifies DTMF signals and FAX send signals.
24 Receiver amplifier (IC501 2/2)
This amplifier amplifies MF tones, dial tones, and FAX receive signals.
25 16 kHz LPF (IC502)
This active low-pass filter removes 16 kHz metering pulses.
26 PBXE (RL4)
This circuits connects one end of the LINE terminal to the PBXE terminal when requested from the PBX line.
4.5 Outline of Parallel Pick Up
Parallel pick up is a function that controls a fax (to make a fax in receive mode) from a telephone set connected
parallel to a fax. The two possible parallel connections of telephone sets A and B are shown in the figure.