Oki OKIOFFICE 84 Service Manual page 412

A3.2 OPE (04W) Circuit Diagram
1. Block diagram
Figure A3.2.1 shows a block diagram of OPE (04W).
The 04W (operation unit) circuit consists of the following blocks:
1) IC1 (one chip MOS-CPU)
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Output ports
Setting LEDs on and off: 8 ports
Specifies the row during key switch matrix scanning: 8 ports
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Input ports
Detect the column whose key is pressed: 8 ports
2) Key switch matrix (8 rows x 8 columns)
3) LEDs (8 LEDs)
4) LCD unit
2. Key switch scanning
Output ports (KSCAN0 to KSCAN7 signal) corresponding to 8 rows of key matrix are scanned sequentially by the
software. In the case 1 is any of output from KSCAN0 to KSCAN7 signal which corresponds to the row 8 in the block
diagram, the software reads input port, KSENS0 to KSENS7, and determines which in the row 8 is pressed.
3. LED drives and LEDs
Eight LEDs (ALARM, PHOTO, LIGHT, etc.) on the control panel are driven by output of IC1 via resistors R1, R4-9
and R11 respectively. An LED lights on when a port output is 1.
4. In case sub-power supply is applied to the fax machine: when PC1-N, HUP-N or RIINT signal is input to OPE unit,
OPE unit controls the main power supply (TLHV board) by outputting the MP/OFF (ACON) signal.
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PC1-N: Presence of document on hopper
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HUP-N: OFF-Hook detection for TEL 1 and TEL 2 terminal
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RIINT: Ringing detection signal
Service Guide OKIOFFICE 84
Chapter A Board Descriptions
Page: 245