Technical Manual

RADIO BOARD DECODER BOARD
AUDIBLE
GND
BATTERY
CONVERSION
RECEIVER
DUAL
DECODER
POCSAG
CONVERTER
SUPPLY
VOLTAGE
BACK-UP
DISPLAY
ILLUMI-
LIQUID
EEPROM
CRYSTAL
DISPLAY
MODULE
SRAM
M
VIBRATE
MOTOR
MICRO-
PROCESSOR
B+
VDD
PL401 SK1
DATA
TAG11262-1
DATA
ADDR
CONTROL
B+
VDD
VDD
B+
PROG
ALERT
GND
RXEN
CHG
LOBAT
NATION
TLA 852/FLA 872
TM1205 Issue 2Page 3 - 2
Figure 3.1: TLA 852/FLA 872 Block Diagram
3.1 CIRCUIT SUMMARY
The TLA 852 and FLA 872 radio paging receivers each consist of two Printed Circuit
Board (PCB) assemblies contained in a plastic case.
The case is constructed in two main parts, the case front and the case back. A cover
on the back of the unit provides access to the battery compartment.
The two boards in the case are:
a) The Radio Board which has the Dual Conversion Receiver, the POCSAG
Decoder, the 1 volt regulator and the audio alert output circuit and transducer.
b) The Decoder Board which has the microprocessor, the EPROM, the SRAM, the
Liquid Crystal Display Module, the LCD illumination, the vibrate motor and the
primary and backup power supplies.
The block diagram of the functional areas of the units is shown in Figure 3.1. Refer
to Section 7 for the circuit diagrams and board layout information.