Kenwood TK-380 Service Manual

Also see for TK-380: User manual Instruction manual Instruction manual Pricing and specification manual Service manual

Contents

TK-38019CIRCUIT DESCRIPTION6-2. Low battery warningThe battery voltage is monitored by the microprocessor(IC19). When the battery voltage falls below the voltage set bythe Low Battery Warning adjustment, the red LED flashes tonotify the operator that it is time to replace the battery. If thebattery voltage falls even more (approx. 5.8V), a beep soundsand transmission is stopped.6. Control CircuitThe control circuit consists of microprocessor (IC19) andits peripheral circuits. It controls the TX-RX unit and transfersdata to and from the display unit. IC19 mainly performs thefollowing;1) Switching between transmission and reception by PTTsignal input.2) Reading system, group, frequency, and program datafrom the memory circuit.3) Sending frequency program data to the PLL.4) Controlling squelch on/off by the DC voltage from thesquelch circuit.5) Controlling the audio mute circuit by decode data input.6) Transmitting tone and encode data.6-1. Memory circuitMemory circuit consists of the CPU (IC19) and a flashmemory (IC17), a flash memory has a capacity of 2M bits thatcontains the transceiver control program for the CPU and datasuch as transceiver channels and operating features.This program can be easily written from an external devices.Data. such as operating status, are programmed into theEEPROM (IC20).● Flash MemoryNote : The flash memory holds data such as written with theFPU (KPG-49D), firmware program (User mode, Test mode,Tuning mode, etc.) This data must be rewritten when replacingthe flash memory.● EEPROMNote : The EEPROM stores tuning data (Deviation, Squelch,etc.).Realign the transceiver after replacing the EEPROM.6-3. Key inputIf the clock is supplied to CLK terminal when the RESterminal (CPU pin 78) of the decade counter (IC301) is set toLow, Q0 to Q7 become High sequentially. Normally, KI1 andKI2 are Low (pulled down). When any key is pressed, KI1 orKI2 become High. The CPU detects which key is pressed,according to the voltage of KI1 and Kl2 and clock timing.Fig. 9 PLL block diagramFig. 10 Memory circuitT/R(TX : Low)T/R A1VCOCV5IC14PLL8BUFFBUFFLPFDT,CP,EPCPUULIC19VCXO IC1FCBALQ18SWD9 TodriveampQ16X1To mixerSWMBD2318IC19IC17CPUIC20EEPROMFLASHLow battery warningThe red LED flashes duringtransmissionThe red LED flashes andcontinuous beep soundswhile PTT pressedBattery conditionThe battery voltage is low butthe transceiver is still usable.The battery voltage is low andthe transceiver is not usableto make calls.Fig. 11 Key inputRESETCLOCKQ0Q1Q2Q3Q4Q5Q6Q7Q8Q9CLOCKINHIBITCARRYOUTFig. 12 Decade counter timing chartIC19CPUQ5Q1Q0Q2Q6Q7Q3VssVddRESCLKCLCAQ9Q4Q8KI1KI2CKKRSTIC30116 keys