Kenwood TK-7100H Service Manual

Also see for TK-7100H: Specifications Service manual

TK-7100H18Control CircuitThe CPU carries out the following tasks:1) Controls the WIDE, NARROW, TX/RX outputs.2) Adjusts the AF signal level of the AF filter (IC251) andturns the filter select compounder on or off.3) Controls the display unit.4) Controls the PLL (IC401).5) Controls the D/A converter (IC161) and adjusts the vol-ume, modulation and transmission power.■ Memory CircuitThe transceiver has an 64k-bit EEPROM (IC66). TheEEPROM contains adjustment data. The CPU (IC101) con-trols the EEPROM through three serial data lines.IC161D/AconverterIC401PLLIC101CPULDDTCKPLLEEEPCKIC101CPUIC66EEPROMEEPDTEEPWP■ Display CircuitThe CPU (IC101) controls the display LCD and LEDs.When power is on, the CPU will use the MBL line to controlthe LCD illumination and key backlight LEDs.The dimmer function is controlled by the switch Q11. TheLCD controller (IC2) controls the functions of the LCDthrough the CE, CK, DI lines from the CPU.■ Key Matrix CircuitThe TK-7100H front panel has function keys. Each ofthem is connected to a cross point of a matrix of the KMI1 toKMO2 ports of the microprocessor. The KMO1 to KMO2ports are always high, while the KMI1 to KMI4 ports are al-ways low.The microprocessor monitors the status of the KMI1 toKMO2 ports. If the state of one of the ports changes, themicroprocessor assumes that the key at the matrix point cor-responding to that port has been pressed.■ EncodeThe QT and DQT signals are output from QT/DQT of theCPU (IC101) and summed with the external pin DI line by thesumming amplifier (IC203) and the resulting signal goes tothe D/A converter (IC161). The DTMF signal is output fromDTMF of the CPU and goes to the D/A converter (IC161). Thesignal is summed with a MIC signal by the summing amplifier(IC203), and the resulting signal goes to the D/A converter(IC161).The D/A converter (IC161) adjusts the MO level and thebalance between the MO and QT/DQT levels. Part of a QT/DQT signal is summed with MO and the resulting signal goesto the VCOMOD pin of the VCO. This signal is applied to avaricap diode in the VCO for direct FM modulation.IC101CPUKMI1KMI2KMI3KMI4KMO2KMO1MONSCNVOLUPVOLDNCHUPCHDNX401TCXOIC161D/A VCOIC203SUMAMPIC203SUMAMPIC161D/AIC401PLLTCXOMODVCOMODHTDIQT/DQTDTMFIC101CPUFig. 10 Control circuitFig. 11 Memory circuitQ10SWQ6SWIC101CPUD2~D5Q9SW D19~D26,D28~D31Q11SWIC2LCDcontrollerCECKDIMBLCOM0~COM3SEG0~SEG30DIMLCDFig. 12 Display circuitFig. 13 Key matrix circuitFig. 14 EncodetCIRCUIT DESCRIPTION