Kenwood TK-190 Service Manual

Also see for TK-190: Pricing and specification manual Service manual Service manual Instruction manual Instruction manual

Contents

16TK-190EEPROMADDRESSDECODEFLASHROMIC412IC415IC414CPUIC406Fig. 9 Memory circuitCPUIC406VCXOX1to PLLIC416 (1/3)x2 INVINVx1 IC416 (3/3)Fig. 10 CPU clock circuitIC2Q1 Q2 Q3 Q4 Q5IC406CPUMonitorSW A SW B IC4TC7SH08FU TCONTTone1 Tone2 OPPTTCLK,DAT,STBTCONTMANDKEY1KEY2OPPTTFig. 11 Key inputCIRCUIT DESCRIPTION7. Control CircuitThe control unit circuit consists of microprocessor IC406and flash memory IC414. It controls the TX-RX unit andtransfers data to and from the control unit. The CPU (IC406)mainly performs the following :1) Switching between transmission and reception by PTTsignal input.2) Reading channel, frequency, and program data from thememory circuit.3) Sending frequency program data to the PLL.4) Controlling squelch on/off from the squelch circuit.5) Controlling the audio mute circuit by decode data input.6) Transmitting encode data (QT, DQT).7) Sending serial data to output expander (IC400, IC403,IC404 and IC405) to various function in the unit.7-1. Memory circuitIC414 has a flash memory with a capacity of 2M bits thatcontains the transceiver control program for the CPU anddata such as transceiver channels and operating features.This program can be easily written from an external de-vices. Data, such as DTMF memories and operating status,are programmed into the EEPROM (IC412).7-2. CPU clockThe CPU clock is generated by VCXO (16.8MHz) and it isfed through an inverter, IC416. This clock was divided into ahalf cycle (1/2 frequency) at the internal CPU. The CPU fur-ther divides this clock to utilize it as the various clocks.7-3. Shift registerIC400, 403, 404 and 405 is an interface IC for output portexpansion. It is used to expand the CPU (IC406) outputports.7-4. D/A converterIC1 and IC603 is used as a conventional semi-fixed-resis-tor converter. It sets the following :1) RX filter tuning2) Transmission power tuning3) Modulation level tuning4) Audio power tuning7-5. Key inputKI1 or KI2 becomes HIGH when any key is pressed (orEnable signal on the optional circuit).When KI1 or KI2 becomes HIGH, KI0 also becomes HIGHto trigger the interrupt to IC406 in order to start the keyscan.When the key scan starts, the output terminals (Q1-Q5)become LOW. Only the key sensing circuit remains HIGH.When a key is pressed, the signal is routed through KI1 orKI2 to the microprocessor. Then, the microprocessor deter-mines which key is pressed using this signals.