Kenwood TKR-D710 Service Manual

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TKR-D710195. Display unitThe Display unit (X54-4060-20) is different from X54-3580-20 which is used in the TKR-750/850/751/851.The Display unit (X54-4060-20) consists of the followingcircuits:(1) LED circuit(2) Key switch circuit(3) Power supply voltage detector5-1. LED circuitThe display circuit consists of various types of LEDs:7-segment type D506 and D507 (red), D503 (red: transmis-sion), D504 (green: busy), D505 (green: power on).IC502 to IC505 are shift registers that convert MCU se-rial data to parallel data and turn on the LEDs.5-2. Key switch circuitThere are PF key 1 to PF key 6 on the Display unit. Usingthese key switches, mode settings are available.The logic signals pushing these key switches are entereddirectly into the MCU (IC20).5-3. Power supply voltage detectorThe Display unit has a power supply voltage detector cir-cuit.The power supply voltage (SB) is divided through tworesistors (R545 and R546).The divided voltage is input to the MCU via the IC508.Fig. 16 Modulation circuit (Analog/Digital signal processing)INT_SPEXT_SPSPOSPISPORDRDRATDTAMODMODIFsignalMICDACIC412DACIC412DACIC412Audio_AMP SWIC402AMP_SWAMP_BMICADC0MICADC1MODDACSPDACPWM1IFRADC1LPFIC501 IC405(C/4)IC404(B/2)IC404(A/2)CR-LPFLPFLPFDETLPFMCUIC20Squelch DACIC14DSPIC6CIRCUIT DESCRIPTION