Operation Board Section; Lcd Section - Panasonic KX-FP80C Service Manual

detection, PC101 (4) becomes low.
(DC LOOP)
Tip L101
L104 RL101(5, 3)
2. CNG/VOX signal detection circuit
The CNG signal from the other party's FAX is detected in MODEM
IC505 (digital board).
(Signal path)
Refer to 2.3.7.1. CHECK
3. Remote receiving
This is the parallel-connected DTMF signal for the TEL or EXT.TEL
mode between T and R. When the other party is a FAX, the unit
switches to FAX receiving.
(Signal Path)
Detects the DTMF signal in the MODEM.

6.11. 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

6.12. 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
JJ103 L105
PC101(1, 2)
SHEET().
Tip1 (EXT.TAM)
L102 POS101
192
Ring 1
Ring