Icom IC-M422 Service Manual

Also see for IC-M422: Instruction manual Service manual

Contents

4 - 44-7 CPU PORT ALLOCATIONSPinNO. Port name Description2 KEYMInput port for keys on HM-150B/SW.Approx. 2.02 V: [Y] key is pushed.Approx. 3.00 V: [Z] key is pushed.Approx. 3.84 V: [H/L] key is pushed.3 TXDET Input port for transmit detected voltage.4 LBAT Input port for low battery detecting.5 SQL Input port for "NOISE" signal from the squelchamplifi er (IC11, pin 4).6 SQLV Input port for squelch adjustment pot (SQLBOARD; R1).7 WXDEC Input port for weather alert signal from theLPF (Q38).8 PDATA Outputs data signal to the PLL IC (IC1, pin 5).9 PCK Outputs clock signal to the PLL IC (IC1, pin 4).10 PSTB Outputs strobe signal to the PLL IC (IC1, pin3).12 EVDATA Outputs volume control signal to the volumeccontroller (IC13, pin 5) for PA circuit.13 EVCK Outputs clock signal to the volume ccontroller(IC13, pin 4) for PA circuit.14 DSDEC Input port for the DSC decode signal from theDSC decoder (IC15, pin 7).28,29CONT1,CONT0Output LCD contrast adjust signal to the CPU(IC1, pin 134).32 COMTXD Outputs serial data signal to the connectedHM-157 (Optional product).33 COMRXD Input port for the serial data signal from theconnected HM-157 (Optional product).34 ECK Outputs clock signal to the EEPROM (LOGICBOARD; IC4, pin 6).35 EDATA I/O port for the EEPROM (LOGIC BOARD;IC4, pin 5) control data.37 NMTXD Outputs NMEA command signal.PinNO. Port name Description38 NMRXD Input port for the NMEA signal.48 PWR Input port for power switch (VR BOARD; R1).Low: When [VOL] is pushed.49 PAMUTEOutputs control signal to the AF (Public Ad-dress) mute circuit (Q65).High: During mute.50 PWRONOutputs power control signal to the powercontrol circuit (Q61, Q62).High: While the transceiver is switched ON.51 TMUTEOutputs transmit mute signal to the APC circuit(IC12, pin 3).High: During mute.53 RCVOutputs control signal to the R5 control circuit(Q53, Q54).High: While receiving.54 H/LOutputs TX power control signal to the TXpower control circuit (Q17, D11).High: 25 WLow: 1 W55 ATTOutputs attenuator control signal to theattenuator (D22).High: Attenuator ON.57 PTT Input port for the [PTT] switch (HM-150B/SW; S1).Low: [PTT] key is pushed.60 UNLKInput port for the "UNLK" signal from the PLLIC (IC1, pin7).High: PLL circuit is unlocked.61 DTRSInput port for the [DISTRESS] key (LOGICBOARD; S9).Low: [DISTRESS] key is pushed.62 RMUTEPOutputs AF (Public Address) mute signal tothe AF mute circuit (IC4, pin12).Low: During mute.63 RMUTESOutputs AF mute signal to the AF mute circuit(IC4, pin 5) for the connected HM-157 (Op-tional product).Low: During mute.64 RMUTEMOutputs AF (internal speaker) mute signal to theAF mute circuit (IC4, pin 6).Low: During mute.65 MMUTEPOutputs microphone (Public Address) mutesignal to the AF mute circuit (IC5, pin 6).Low: During mute.66 MMUTESOutputs microphone mute signal to the AFmute circuit (IC5, pin 5) for the connectedHM-157 (Optional product).Low: During mute.67 MMUTEMOutputs microphone (HM-150B/SW) mute sig-nal to the AF mute circuit (IC5, pin 13).Low: During mute.68 PTTSOutputs AF/MIC control signal to the AF mutecircuit (IC6, pin 5).High: PTT switch (HM-157) is pushed69 PTTM Outputs AF/MIC control signal to the AF mutecircuit (IC5, pin 12).70 LO/DXInput por t for the [LO/DX] key (LOGICBOARD; S8).Low: [LO/DX] key is pushed.4-6 POWER SUPPLY CIRCUITSLine DescriptionHV The voltage from the connected DC power supply.L5VCommon 5V converted from the HV line at the L5V regulator(LOGIC BOARD; IC3).The converted voltage is applied to the CPU (LOGICBOARD; IC1)VCC Same voltage as the HV line whitch is passed through thepower control circuit (Q61, Q62).S5V Common 5V converted from the VCC line at the +5 regulatorcircuit (IC10).T5 Transmit 5V controlled by the T5 control circuit (Q52, Q57)using the "SEND" signal from CPU (LOGIC BOARD; IC1, pin 52).R8Receive 8 V converted from the VCC line at the R8 regulator(Q55, Q56).The converted voltage is applied to the receiver circuits.R5Receive 5V controlled by the R5 control circuit (Q53, Q54)using the "RCV" signal from CPU (LOGIC BOARD; IC1,pin 53).The controlled voltage is applied to the receiver circuits.