Oki OKIOFFICE 84 Service Manual page 421

A3.5 UNC, WN5, FN5 and DN5 Circuit Diagram
The NCU board is selected from UNC, WN5, FN5 and DN5 because it differs depending on country's specifications.
Therefore, the NCU circuit diagram is destined for the following countries.
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UNC circuit diagram
US and Canada.
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WN5 circuit diagram
Sweden, Finland, The Netherlands, Ireland, Portugal, New Zealand, Australia, Belgium, Spain, Greece, Norway,
Denmark, Italy, and other countries.
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FN5 circuit diagram
France and UK
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DN5 circuit diagram
Germany, Switzerland and Austria.
1. Block diagram
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Figure A3.5.1 shows a block diagram of UNC circuit.
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Figure A3.5.2 shows a block diagram of WN5 circuit.
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Figure A3.5.3 shows a block diagram of FN5 circuit
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Figure A3.5.4 shows a block diagram of DN5 circuit.
2. General functions of this circuit are as follows:
1) Generates and detects signals to be exchanged with a telephone exchange or network in Phases A and E defined
by ITU T.30.
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Loop formation for call origination
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Line current detection (see note 1) before call origination
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Dial tone detection (see note 1)
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Generation of dial pulses (see note 2)
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Busy tone detection (see note 1)
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Ringing signal detection
2) Sends various data and signals from the R51 board to the telephone line after amplification.
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Picture data/Protocol/Tonal signals/PB tone, etc.
3) Sends the following signals received from the line to the R51 board as data after amplifica-tion.
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Picture data/Protocol/Tonal signals, etc.
Service Guide OKIOFFICE 84
Chapter A Board Descriptions
Page: 250