Icom IC-M502 Service Manual
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Icom IC-M502 Service Manual

Vhf marine transceiver
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SERVICE
MANUAL
VHF MARINE TRANSCEIVER
iM502

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Summary of Contents for Icom IC-M502

  • Page 1 SERVICE MANUAL VHF MARINE TRANSCEIVER iM502...
  • Page 2 This service manual describes the latest service information NEVER connect the transceiver to an AC outlet or to a DC for the IC-M502 VHF MARINE TRANSCEIVER at the time of power supply that uses more than 16 V. This will ruin the transceiver.

  • Page 3: Table Of Contents

    IC-M502 ........

  • Page 4: Specifications

    SECTION 1 SPECIFICATIONS ‘ ‘ GENERAL • Frequency coverage : 156.025–157.425 MHz (Tx) 156.050–163.275 MHz (Rx) • Mode : 16K0G3E (FM) 16K0G2E (DSC) • Usable channels : All international and USA channels • Power supply requirement : 13.8 V DC (negative ground) •...
  • Page 5 ‘ ‘ VHF MARINE CHANNEL LIST Channel No. Frequency (MHz) Channel No. Frequency (MHz) Channel No. Frequency (MHz) Transmit Receive Transmit Receive Transmit Receive 156.050 160.650 157.050 157.050 156.675 156.675 156.050 156.050 157.100 161.700 156.725 156.725 156.100 160.700 157.100 157.100 156.875 156.875 156.150...

  • Page 6: Inside Views

    SECTION 2 INSIDE VIEWS 2-1 IC-M502 • MAIN UNIT AF power amplifier (IC14: LA4425A) PLL IC (IC2: µPD3140GS) VCO circuit Reference oscillator (X2: CR-659 21.25 MHz) Drive amplifier (Q12: 2SC2954) 1st IF filter (FI1, FI2: FL-310) Power module* (IC3: SC-1302)

  • Page 7: Hm-127 (Optional Unit)

    2-2 HM-127 (OPTIONAL UNIT) • TOP VIEW (DS1: A0119) • BOTTOM VIEW System clock (X1: CSTCC4.91MG) (IC1: µPD789405AGK-A30-9EU) Dimmer circuit Data buffer circuit Reset IC 8V regulator (IC7: S-80928ANMP) (IC6: TA7808F) 5V regulator Volume IC (IC5: TA78L05F) (IC3: M62429FP) AF/MIC switch (IC9: TC4W53FU) AF amplifier MIC amplifier...

  • Page 8: Disassembly Instruction

    SECTION 3 DISASSEMBLY INSTRUCTION CAUTION: DISCONNECT the DC power cable from the transceiver before performing any work on the trans- ceiver. Otherwise, there is danger of electric shock and/or equipment damage. • Opening the transceiver case • Remove the MAIN unit q Unscrew 6 screws A, and remove the front unit.

  • Page 9: Circuit Description

    SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS The signals from the RF circuit are mixed with the VCO sig- nals at the 1st mixer circuit (Q3) to produce a 21.7 MHz 1st 4-1-1 ANTENNA SWITCHING CIRCUIT IF signal. The antenna switching circuit functions as a low-pass filter while receiving and as resonator circuit while transmitting.

  • Page 10: Transmitter Circuits

    4-1-5 AF AMPLIFIER CIRCUIT The amplified signals are applied to the IDC amplifier (IC13a, pin 2) via the analog switch (IC12, pins 9, 8 and pins The AF amplifier circuit amplifies the detected signals to 4, 3) and are passed through the splatter filter (IC13b) to drive a speaker.

  • Page 11: Pll Circuit

    4-3 PLL CIRCUITS The pulse-type signal is converted into DC voltage (lock voltage) at the loop filter (R252–R254, C292–C294), and is 4-3-1 GENERAL then applied to varactor diodes (D6, D7) of the TX-VCO to The PLL circuit provides stable oscillation of the transmit fre- stabilize the oscillated frequency.

  • Page 12: Dsc Circuit

    4-4 DSC CIRCUITS (DSC UNIT) 4-6-2 LOGIC UNIT • CPU 4-4-1 DSC ENCODE CIRCUIT IC1 is an 8 bit single chip micro-computer and contains LCD The DSC signal created at CPU (IC16), is passed through driver, serial I/O, timer, A/D converter, programmable I/O, the buffer amplifier (Q33) and applied to the analog switch ROM and RAM.
  • Page 13 4-7-2 MAIN CPU (MAIN unit; IC16) Port Port Description Description number name number name Outputs control signal to the analog Output port for the cloning data to the CLTX switch (IC12) for passing through the buffer (MAIN unit; Q37). STRU optional VOICE SCRAMBLER unit Outputs clock signal for EEPROM (UT98 or UT-112).

  • Page 14: Adjustment Procedures

    SECTION 5 ADJUSTMENT PROCEDURES 5-1 PREPARATION I REQUIRED TEST EQUIPMENT EQUIPMENT GRADE AND RANGE EQUIPMENT GRADE AND RANGE Output voltage : 13.8 V DC Frequency range : 300–3000 Hz DC power supply Audio generator Current capacity : 10 A or more Measuring range : 1–500 mV Measuring range...

  • Page 15: Pll Adjustments

    5-2 PLL ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST LOCK • Operating channel : ch16 MAIN Connect a digital 3.5 V MAIN VOLTAGE • Receiving multi-meter or oscil- loscope to check point CP1. • Operating channel : ch116 4.5–6.0 V Verify •...

  • Page 16: Transmitter Adjustments

    5-3 TRANSMITTER ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST OUTPUT • Operating channel : ch16 Rear Connect 25 W MAIN POWER • Output power : High Panel power meter to the • Transmitting antenna connector. •...

  • Page 17: Receiver Adjustments

    5-4 RECEIVER ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST SENSITIVITY • Operating channel : ch16 MAIN Connect a DC volt- Maximum voltage MAIN • [SQUELCH] control: meter to check point Max. counterclockwise CP3. • Set the internal speaker OFF in the SET mode, and connect a distortion meter with a 4 Ω...

  • Page 18: Parts List

    SECTION 6 PARTS LIST 6-1 IC-M502 [LOGIC UNIT] [LOGIC UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 1140009280 S.IC µPD78F9418AGK-9EU 7030003680 S.RESISTOR ERJ3GEYJ 104 V (100 kΩ) 1140008960 S.IC HD66712SA03FS 7030003590 S.RESISTOR ERJ3GEYJ 183 V (18 kΩ) 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ) 7030003630 S.RESISTOR...

  • Page 19: Vol Unit

    [VOL UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 7210003080 VARIABLE TP96N97-15F-10KA-2345 1110003200 S.IC TA31136FN (EL) 1130007610 S.IC µPD3140GS-E1 (DS8) 1150001540 IC M57710-A/SC-1302 6510009470 CONNECTOR S3B-ZR 1110003750 S.IC M5218AFP 600C 1110003650 S.IC NJM2211M-TE1 1130007420 S.IC TC7W14FU (TE12L) 8900009860 CABLE OPC-970 1110002030 IC TA7808S 1180001070 S.IC TA7805F (TE16L)
  • Page 20 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 1710001080 DIODE XB15A308 7030003450 S.RESISTOR ERJ3GEYJ 122 V (1.2 kΩ) 1710001080 DIODE XB15A308 7030003460 S.RESISTOR ERJ3GEYJ 152 V (1.5 kΩ) 1750000550 S.DIODE 1SS355 TE-17 7030003680 S.RESISTOR ERJ3GEYJ 104 V (100 kΩ) 1790000700 DIODE DSA3A1 7030003500 S.RESISTOR ERJ3GEYJ 332 V (3.3 kΩ)
  • Page 21 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION R119 7030003550 S.RESISTOR ERJ3GEYJ 822 V (8.2 kΩ) R210 7030003800 S.RESISTOR ERJ3GEYJ 105 V (1 MΩ) R120 7030003770 S.RESISTOR ERJ3GEYJ 564 V (560 kΩ) R211 7030003650 S.RESISTOR ERJ3GEYJ 563 V (56 kΩ) R121 7030003710 S.RESISTOR ERJ3GEYJ 184 V (180 kΩ)
  • Page 22 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 4030009510 S.CERAMIC C1608 CH 1H 010B-T-A C109 4030007040 S.CERAMIC C1608 CH 1H 180J-T-A 4030007010 S.CERAMIC C1608 CH 1H 100D-T-A C110 4030006860 S.CERAMIC C1608 JB 1H 102K-T-A 4030009570 S.CERAMIC C1608 CH 1H 0R3B-T-A C111 4030006860 S.CERAMIC C1608 JB 1H 102K-T-A...
  • Page 23 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION C206 4030007090 S.CERAMIC C1608 CH 1H 470J-T-A C312 4030006900 S.CERAMIC C1608 JB 1E 103K-T-A C207 4030006860 S.CERAMIC C1608 JB 1H 102K-T-A C314 4550006700 S.TANTALUM ECST1AY106R C208 4030006850 S.CERAMIC C1608 JB 1H 471K-T-A C315 4030006860 S.CERAMIC C1608 JB 1H 102K-T-A...
  • Page 24 6-2 HM-126 6-3 HM-127 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 7010006890 RESISTOR R20J 12 kΩ 1140009280 S.IC µPD78F9418AGK-9EU 7010006880 RESISTOR R20J 6.8 kΩ 1110001810 S.IC TA7368F (TP1) 7010006900 RESISTOR R20J 15 kΩ 1110004490 S.IC M62429FP 700C 7010006910 RESISTOR R20J 33 kΩ...
  • Page 25 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ) 5040002310 S.LED SML-311YTT86 7030003640 S.RESISTOR ERJ3GEYJ 473 V (47 kΩ) DS10 5040002310 S.LED SML-311YTT86 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ) 7030003520 S.RESISTOR ERJ3GEYJ 472 V (4.7 kΩ) ERJ3GEYJ 470 V (47 Ω) 7030003280 S.RESISTOR 7700002480 MICROPHONE...
  • Page 26 NI-ZU: Nickel-zinc ZK: Black Screw M3 × 8 SUS MP38 8810004540 MP40 8850000690 Flat washer M3 (3×7×0.5) SUS MP41 8810006050 Icom screw E 7 MP43 8930052430 2345 A-IC clip MP44 8930052440 2345 B-IC clip MP45 8930053030 2345 earth plate MP46...
  • Page 27 MP41 (CH) MP40 (CH) J2 (CH) MP22 (CH) MP37 (CH) MP27 (CH) MP5 (CH) MP3 (CH) MP2 (CH) W1 (CH) MP38 (CH) MP29 (CH) EP1 (CH) J1 (CT) MP45 (CH) MP12 (CH) MP33 (CH) MP46 (CH) MP31 (CH) PWR-CORD MP34 (CH) UNIT MP6 (CH) MP18 (CH)
  • Page 28 2417 plate 8900010280 Cable OPC-1000 MP12 8820001150 2352 screw MP13 8210017250 2417 rear panel [BLACK] MP13 8850001850 ICOM washer (Y) 8210017300 2417 rear panel (A) [WHITE] 8950005110 2289 mic hanger MP14 8930052340 O-ring (AE) MP14 8310049970 2417 R-plate Screw PH M3 × 16 SUS...
  • Page 29 SECTION 8 SEMI-CONDUCTOR INFORMATION • TRANSISTORS AND FET’S • DIODES 2SA1576A T106R 2SB1132 T100 R 2SB1143 S 2SC2714-Y 2SC2954 T2B 1SS355 1SS375-TL DA204 U DAN202 U DAP202U (Symbol: A) (Symbol: FH) (Symbol: K) (Symbol: N) (Symbol: P) (Symbol: FR) (Symbol: BARB) (Symbol: B1143) (Symbol: QY) (Symbol: QK)
  • Page 30 SECTION 9 BOARD LAYOUTS 9-1 VOL UNIT 9-3 SQL UNIT to LOGIC unit J3 to MAIN unit W1 9-2 DIAL UNIT to LOGIC unit J3 9 - 1...

  • Page 31: Logic Unit

    9-4 LOGIC UNIT • TOP VIEW 9 - 2...
  • Page 32 • BOTTOM VIEW to HM-126 J2 to SQL and DIAL units to MAIN unit J4 9 - 3...

  • Page 33: Main Unit

    9-5 MAIN UNIT • TOP VIEW R304 EXT SP to VOL unit J1 to EXT-GPS to HM-126 J1 for FLASH to optional unit UT-98 or UT-112 from LOGIC unit J4 from CTRL unit J2 9 - 4...
  • Page 34 • BOTTOM VIEW 9 - 5...

  • Page 35: Ctrl Unit

    9-6 CTRL UNIT 9-9 HM-127 (OPTIONAL UNIT) • TOP VIEW • TOP VIEW to MAIN unit J3 9-7 PWR-CORD UNIT 9-8 HM-126 • TOP VIEW • TOP VIEW to MAIN unit SPMIC MICE KGND KEYM 9 - 6...
  • Page 36 • BOTTOM VIEW (HM-127) • BOTTOM VIEW (CTRL) • BOTTOM VIEW (HM-126) • BOTTOM VIEW (PWR-CORD) PWRC RRXDA RTXDA PTTC MICG AF/MIC to IC-M502 CTRL unit J1 9 - 7...

  • Page 37: Block Diagram

    SECTION 10 BLOCK DIAGRAM EXT.SP ALFY450E OPTION Q31 DTC144EU Q32 2SC4116 EXTERNAL SPEAKER ATTA ATTB TA31136FN IC4B FI1, FI2 3 stage 1 stage D16, D17 NJM4558M FL-310 XB15A308 2SC2714 3SK292 WX ALERT 3SK166 2nd IF HM-126 IC4A SPEAKER MIC IC5 NJM2211M Q18 2SC4116 NJM4558M IC6 TC7W14FU...

  • Page 38: Voltage Diagram

    SECTION 11 VOLTAGE DIAGRAM 11-1 LOGIC UNIT DTRS SQL UNIT DISTRESS DS16 DS11 SML-311YT DS3–DS17 SQLG SML-311YT SQLV SQL5V SCAN DS15 DS12 DS10 TSD0393 CHWX SQL5V CH16 SQLV SQLV SQLG SQLG DS14 DS13 DIALA DIALA SCAN CH/WX DIALB DIALB DIAL UNIT DIALB DS17 POWER SW...

  • Page 39: Main Unit

    11-2 MAIN UNIT MAIN UNIT MAIN (1) TMODE TMODE TAUX3 TAUX3 DEMOD DEMOD PLL BUS BUS LINE OPT BUS MAIN BUS SQLI R199 100k R182 RMUTS DTA144EU DTA144EU 21.7MHz IC15 RMUTM ATT1 ATT2 0.001 0.001 0.22 S-80928ANMP R200 R304 RESET CD 5 ATTB 100k...
  • Page 40 MAIN (2) CHASSIS DEMOD BUS LINE C308 IC20 R263 NJM2125F R266 R268 4.66V SQLI C158 C317 C307 R264 R265 R267 IC4B C309 R102 0.22 R103 R104 100k NJM4558M 0.22 C161 DEMOD NJM2211M 0.033 CAP 14 C148 R109 CAP 13 C153 C156 R 12 0.012...

  • Page 41: Hm-127 (Optional Unit)

    11-3 HM-127 (OPTIONAL UNIT) MAIN UNIT CHASSIS TA7368F POUT 036D0801 PWGND PREGND PHASE RIPPLE 10KEY 0.047 SML-311YT SML-311YT 10KEY SML-311YT 2SJ144 10KEY SKQLLC SKQLLC SKQLLC DOWN M62429FP DS10 470k SML-311YT VIN1 VIN2 VOUT1 VOUT2 100k 100k SKB-2746 LPC VRDAT DATA MICG 10KEY FY1101F-TR...

  • Page 42: Hm-126

    11-4 HM-126 KUC2123-030245 470p UP-ON 2.0V 470p DN-ON 3.0V W1 (CHASSIS) H/L-ON 3.8V S36G04K-4 KEYM KEYM GREEN GREEN KEYM to LOGIC unit J1 KGND KGND BROWN BROWN KGND (IC-M501EURO) MICE MICE SPMIC SPMIC WHITE BLACK SKHHLP014A BLUE BLUE HANG HANG MICE to MAIN unit J7 (IC-M501EURO)
  • Page 43 Fax : ( 604 ) 952-0090 Icom (UK) Ltd. : http://www.icomcanada.com Unit 9, Sea St., Herne Bay, Kent, CT6 8LD, U.K. Icom (Australia) Pty. Ltd. Phone : 01227 741741 Fax : 01227 741742 A.B.N. 88 006 092 575 : http://www.icomuk.co.uk 290-294 Albert Street, Brunswick, Victoria, 3056, Australia Icom France S.a...
  • Page 44 S-13710HZ-CD © 2000 Icom Inc. 1-1-32, Kamiminami, Hirano-ku Osaka 547-0003, Japan...

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