Maintenance Manual
5
U100 pin 63. This pin is analog-to-digital conversion port and the microprocessor measure the voltage
level. And the result is indicated on the LCD battery indicator pixel. When the battery voltage drops
below approximately 6.3Vdc, generates a low battery alert sound.
Liquid Crystal Display (LCD)
The LCD assembly is on the Board. It consists of a diffuser, zebra strips, the LCD and a lens. The primary
function of the board is to drive a 112 x 16 graphic display and to drive the individual segment lines of
the LCD.
Serial display data from the microprocessor is sent to the LCD driver on the LCD panel. IIC DATA and
IIC CLK lines (Inter Integrated Circuit BUS) are pass through the zebra strips on the LCD driver. Another
function is to provide back lighting of the LCD module using for LED devices (D102). The diffuser
placed immediately above the LED evenly distributes the light.
Audio Processor
The Audio Processor U101 handles nearly all the audio functions in the PZ-series radio. It has the audio
filter that operates the basic functions of radio, the Limiter, the Splatter Filter, the Compander and the
Scrambler. It can be controlled by microprocessor.
The main functions are as followings.
The amplifier and attenuator functions for Transmitting and Receiving signals
The Pre/De-emphasis circuitry is built-in.
The Compressor and Expander are built-in.
The Scrambler and De-scrambler of frequency inversion type (3.388 KHz) is built-in.
Max Deviation level adjustment is available.
The 12.5 / 25 KHz filter is built-in.
The CTCSS and DCS filter is built-in and the level adjustment is available.
EDACS & Conventional Modes RX Audio (sheet4)
For transmitting of PZ series radio, the microphone bias can be supplied to microphone through Q109,
R182, R183 and R184 when pressing the PTT key button. When the VOX mode is activated, the bias can
be supplied automatically. The voice signal made through microphone is entered into audio processor
chip. (U101) In case of external speaker-microphone, the bias also can be supplied and generate a
EXT_PTT signal to microprocessor.
