Kenwood TK-5310 Service Manual Download Page 20

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TK-5310

CIRCUIT DESCRIPTION

6. Control Circuit

The control circuit consists of CPU (IC5) and its peripheral

circuits. It controls the TX-RX unit and transfers data to the
Control unit. IC5 mainly performs the following;
1) Switching between transmission and reception by PTT

signal input.

2) Reading system, zone, frequency, and program data from

the memory circuit.

3) Sending frequency program data to the PLL.
4) Controlling squelch on/off by the DC voltage from the

squelch circuit.

5) Controlling the audio mute circuit by decode data input.
6) Transmitting tone and encode data.

6-1. Memory Circuit

Memory circuit consists of the CPU (IC5) and a flash

memory (IC6). A flash memory has a capacity of 16M bits and
contains the transceiver control program for the CPU. It also
stores the data for transceiver channels and operating param-
eter that are written by the FPU. This program can be easily
written from an external devices.

The EEPROM (IC3) stores the last channel data, the scan

on status, and other parameters.

■

Flash memory

Note :

The flash memory stores the data that is written by

the FPU (KPG-95D), and firmware program (User mode, Test
mode, Tuning mode, etc.). This data must be rewritten when
replacing the flash memory.

■

EEPROM

Note :

The EEPROM stores tuning data (Deviation, Squelch,

etc.).
Realign the transceiver after replacing the EEPROM.

■

Real-time clock

The clock function is based on real-time clock IC (IC2).

When the power supply is off, it is backed up by an internal
secondary lithium battery

6-2. LCD (K2, K3, K5 and K6 models only)

The LCD is controlled using the bus lines on the connector

(CN800) of the control unit (X57 B/5).

The LCD contrast voltage is corrected using IC800. The

thermometry result used by the temperature IC (IC1) is
corrected by the CPU (IC5), and the contrast voltage is output
as a pulse ripple from the LCDV terminal (pin 28) of the CPU.
The filter then smoothens the voltage which in turn is input
into pin 3 of IC800.

6-3. Temperature Detection Circuit

T h e t e m p e r a t u r e d e t e c t i o n c i r c u i t d e t e c t s t h e

temperature using a temperature IC (IC1) and corrects the
thermal characteristic change of the squelch or LCD.

6-4. Key Detection Circuit

Keys are detected using three shift registers (IC801,

IC802, IC803).

The KIN signal that is normally pulled down goes high

when any key is pressed.

6-5. Low Battery Warning

The battery voltage is divided using R22 and R23 and is

detected by the CPU (IC5). When the battery voltage falls
below the voltage set by the Low battery warning
adjustment, the red LED blinks to notify the operator that it is
time to replace the battery. If the battery voltage falls even
more (approx. 5.8V), a beep sounds and transmission stops.

Low battery warning

Battery condition

The red LED blinks during

The battery voltage is low but

transmission.

the transceiver is still usable.

The red LED blinks and

The battery voltage is low and

the warning tone beeps while

the transceiver is not usable to

the PTT switch is pressed.

make calls.

6-6. Battery Type Detection

The transceiver automatically detects the battery type,

measuring the resistance between the S-terminal and GND
terminal on the battery pack and changes the supplied
voltage to the S-terminal as below. The microprocessor then
detects the battery type.

6-7. VOX

The VOX function can be used only with an external

microphone.

The VOX (Voice Operated Transmission) function detects

voice input to the microphone and automatically switches
between transmission and reception. However, if a
scrambler board is installed (Extended Function Voice
Scrambler is selected with FPU), VOX does not operate.

Fig. 9

Memory circuit

CPU

EEPROM

FLASH

IC5

IC6

IC3

Fig. 10

Clock diagram

IC454

CODEC