Operation Board Section; Lcd Section - Panasonic KX-FM89BX Service Manual

Use modem cable or RS-232C data communication cable.
(Cable type is specified in Operating Instructions..)
Note:
The open circuit driver voltage (output) of this set is +12V ~ -12V. The minimum input signal
voltage must fall outside the transition region of ±3V.
The output voltage range that is terminated with a load between 3kW and 7kW will be between ±
5V and ±12V.

6.12. OPERATION BOARD SECTION

The unit consists of a LCD (Liquid crystal display), KEYs and LEDs (light-emitting diodes). They
are controlled by the Gate Array (IC301) and ASIC (IC501: on the DIGITAL BOARD). (Fig.-a) / The
key matrix table is shown below.
Key Matrix

6.13. LCD SECTION

The Gate Array (IC301) works only for writing the ASCII code from the data bus (D4~D7). V0 is
supplied for the crystal drive.
R303(R377) and R305(R379) are density control resistors.
Consequently, in this unit, the timing (positive clock) is generated by the LCD interface circuitry
in the gate array (IC301).
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