Kenwood TK-5310 K4 Service Manual page 20

TK-5310
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
IC5
CPU
FLASH
IC6
Fig. 9 Memory circuit
9.216MHz
IC5
(2/3,3/3)
CPU
9.216MHz
IC8
DSP
IC457
FPGA
IC454
CODEC
Fig. 10 Clock diagram
20
CIRCUIT DESCRIPTION
IC3
EEPROM
IC453 IC453
(1/3)
IC455
18.432MHz
18.432MHz
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
The temperature detection circuit detects the
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
The red LED blinks during
transmission.
The red LED blinks and
the warning tone beeps while the transceiver is not usable to
the PTT switch is pressed.
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.
Battery type
Battery case
Li-ion battery
Ni-Cd battery
Ni-MH battery
X450
VCXO
6-7. VOX
The VOX function can be used only with an external
18.432MHz
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.
Battery condition
The battery voltage is low but
the transceiver is still usable.
The battery voltage is low and
make calls.
Input voltage of S-terminal
0~0.2V
0.85~1.02V
3.23~3.37V
1.71~1.95V
Resistor value
Short
47 kΩ
Open
150 kΩ