Kenwood TK-7100 Service Manual

Also see for TK-7100: Instruction manual Specifications Specifications Instruction manual Instruction manual

TK-710021■ Decode• QT/DQT/DTMFThe signal (W/NO (EVOL2)) goes to SIGNAL (pin 88) ofCPU (IC101). The QT/DQT signal will pass through the low-pass filters in the CPU (IC101) and be decoded within theCPU (IC101). The DTMF signal will be decoded within theCPU (IC101).■ D/A ConverterThe D/A converter (IC161) is used to adjust MO modula-tion, AF volume, TV voltage, FC reference voltage, and PCPOWER CONTROL voltage level.Adjustment values are sent from the CPU as serial data.The D/A converter has a resolution of 256 and the followingrelationship is valid:D/A output = (Vin – VDAref) / 256 x n + VDArefVin: Analog inputVDAref: D/A reference voltagen: Serial data value from the microprocessor (CPU)IC101CPUSIGNAL W/NO (EVOL2)88Q71SWQ31SWQ32SWQ61SWIC33AVRD61BIC34RSTSBCIGNR77R76R39R40INT5MBATTIC101CPUPOWERSWPOWERRESET5MIC35AVRSBIGNFig. 15 DecodeFig. 16 Power supply circuitCIRCUIT DESCRIPTIONPower Supply CircuitWhen the power switch on the display unit is pressed, thepower port on the display unit which is connected port 17(POWER), goes low, then port 82 (SBC) goes high, Q32 turnson, SB SW (Q31) turns on and power (SB) is supplied to theradio.When the DC power supplied to the radio, the voltageregulator IC (IC33) supply into the CPU VDD and reset voltagedetect IC (IC34). IC34 will generate signal (RESET) in to thereset terminal on the CPU (IC101) to carry out a power ONreset. Also, CPU (IC101) is checking on port 91 (Battery Volt-age). If DC power is less than about 9.5V, the radio is unableto power on.When the DC power voltage deceases from normal volt-age, the INT voltage detector IC (IC35) will set to high on CPUport 18 (INT) if B line will became less than about 9.5V. ThenCPU send to EEPROM (IC66) the backup data and go intoSTOP mode.This circuit has an overvoltage protection circuit. If a DCvoltage of 18V or higher is applied to the base of Q61, thisvoltage turns Q61 on and turns Q32 and SB off.