Icom IC-R75 Service Manual
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Icom IC-R75 Service Manual

Communications receiver
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  • Page 1 SERVICE MANUAL COMMUNICATIONS RECEIVER...
  • Page 2 NEVER connect the receiver to an AC outlet or to a DC This service manual describes the latest service information for the IC-R75 at the time of publication. power supply that uses more than 16 V. Such a connection could cause a fire hazard and/or electric.

  • Page 3: Table Of Contents

    TABLE OF CONTENTS SECTION SPECIFICATIONS SECTION INSIDE VIEWS SECTION CIRCUIT DESCRIPTION RECEIVER CIRCUITS ........... . .3-1 PLL CIRCUITS .
  • Page 4 SECTION 1 SPECIFICATIONS GENERAL • Frequency range Version Frequency coverage USA, EUR, 30 kHz – 60 MHz* UK, OTH 30 kHz – 30 MHz Specifications guaranteed for 0.1 – 29.99 MHz and 50 – 54 MHz Specifications guaranteed for 0.1 – 29.99 MHz •...

  • Page 5: Section 2 Inside Views

    SECTION 2 INSIDE VIEWS MAIN UNIT PLL UNIT 1st mixer circuit 2nd mixer circuit 1st IF filter (FI701) VCO circuit Fuse (3A) PLL IC (IC21) Bandpass filter 2nd IF circuit Noise blaker circuit Back up battery 2nd IF filter (BT 1521) (FI761: FL-272) 3rd IF filter 3rd LO circuit...

  • Page 6: Section 3 Circuit Description

    3-1-1 RF SWITCHING CIRCUIT (MAIN UNIT) C170–C175, L171–L173 via the limitter circuit (D141, D142). The IC-R75 has two antenna connectors. RF signals enter A diode is removed at the entrance of the low-pass filter. This either the [50 Ω ANT.] or [450 Ω ANT.] connector.
  • Page 7 3-1-3 PRE-AMPLIFIER CIRCUIT (MAIN UNIT) The 69.0415–129.0115 MHz 1st LO signal is applied to an LO amplifier (Q411) from the PLL unit via J411, and then The pre-amplifier circuit uses low noise junction FETs (Q381, passes through the low-pass filter (L421, L422, C422–C425). Q382) or wideband amplifier (IC391) to provide gain over a The filtered signal is applied to the 1st mixer circuit.
  • Page 8 3-1-6 NOISE BLANKER CIRCUITS (MAIN UNIT) When the mode is selected FM mode, the filtered 3rd IF sig- The IC-R75 uses a trigger noise blanker circuit which nal is amplified at the 3rd IF amplifier (Q891), and is then removes pulse-type noise signals at the noise blanker gate applied to the FM demodulator circuit.

  • Page 9: Pll Circuits

    AF signal. The 3rd IF signal from the IF amplifier (Q911) is The AGRS signal resets the AGC circuit when IC-R75 is amplified at the buffer amplifier (Q1031), and is then applied working the memory scaning.

  • Page 10: Logic Circuits

    The oscillated signal at the VCO1 and VCO2 circuit is ampli- 3-2-6 BFO CIRCUIT (PLL AND MAIN UNIT) fied at the LO-amplifier (PLL unit; Q91), and passes through The 30 MHz reference frequency is amplified at the Q201 on the low-pass filter (PLL unit; Q92, D91, D92, L91, L93, the PLL unit, and is applied to the 10 bits DDS-IC (PLL unit;...

  • Page 11: Power Supply Circuits

    IC-R75 has a backup switch circuit (Q511 and Q512). When amplifier (IC391) via the REG2 regulator circuit IC-R75 is supplied to 13.8 V to connect the AC adapter, the (Q391) and the AM detector circuit (IC2001, pin “H5V” signal is applied to Q512, pin 4, and then Q511 is OFF.

  • Page 12: Port Allocations

    3-5 PORT ALLOCATIONS 3-5-1 CPU (LOGIC UNIT; IC101) Port Port Description Description number name number name Input port for [0] and [ENT] switch Input port for the [MW] switch. KEY6 from the 10-key. CLRK Input port for the [CLR] switch. Input port for the reset signal.

  • Page 13: Section 4 Adjustment Procedures

    SECTION 4 ADJUSTMENT PROCEDURES 4-1 PREPARATION ‘ ‘ REQUIRED TEST EQUIPMENT EQUIPMENT GRADE AND RANGE EQUIPMENT GRADE AND RANGE Output voltage : 13.8 V DC Frequency range : DC–20 MHz DC power supply Oscilloscope Current capacity : 2 A or more Measuring range : 0.01–20 V Frequency range...

  • Page 14: Pll Adjustment

    4-2 PLL ADJUSTMENT ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST • Displayed frequency Connect fre- 60.00000 MHz REFERENCE : 29.99999 MHz quency counter to FREQUENCY • Mode : USB Connect Maximum voltage L4, L5 voltmater to P1. •...
  • Page 15 • PLL UNIT VCO voltage adjustment 1st and 3rd LO voltage check point HCP71 VCO voltage check point Reference frequency check point Reference frequency adjustment (for output voltage is maximum) Reference frequency adjustment (for output frequency is 60.0000 MHz) P151 3rd LO frequency check point P201 BFO voltage check point...
  • Page 16 4-3 RECEIVER ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST RECEIVER • Displayed frequency Rear Connect Pre-set to center MAIN R444 SENSITIVITY : 14.10000 MHz Panel milli-volt meter to R898 • Mode : USB the [EXT SP] jack with an 8 Ω...
  • Page 17 RECEIVER ADJUSTMENTS (continued) ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST 1ST IF • Displayed frequency Rear Connect Maximum output level MAIN L461, FILTER : 14.10000 MHz panel milli-volt meter to L462 • Mode : FM the [EXT SP] jack with an 8 Ω...

  • Page 18: Receiver Adjustment

    RECEIVER ADJUSTMENTS (CONTINUED) ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST NOISE • Displayed frequency MAIN Connect the oscillo- Pre-set to center MAIN R736 BLANKER : 14.10000 MHz scope to the check Minimun voltage L731, • Mode : USB point CP731.

  • Page 19: Set Mode Adjustment

    4-4 SET MODE ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITION DISPLAY OPERATION ENTERING • Turn power OFF • When success entering adjustment set ADJUSTMENT • Connect a terminator to the mode, shown “PBT SET” on the display. SET MODE [REMOTE] connector on the rear •...

  • Page 20: Section 5 Parts List

    SECTION 5 PARTS LIST [VR BOARD] [LOGIC BOARD] ORDER ORDER DESCRIPTION DESCRIPTION R131 7210003040 VARIABLE TP96D26-22F-10KBX2-2240 L503 6200003950 S.COIL HF50ACC 322513-T R141 7210003030 VARIABLE TP96D00-22F-10KBX2-2240 R143 7030003540 S.RESISTOR ERJ3GEYJ 682 V (6.8 kΩ) R112 7030003800 S.RESISTOR ERJ3GEYJ 105 V (1 MΩ) R121 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ)
  • Page 21 [LOGIC BOARD] [LOGIC BOARD] ORDER ORDER DESCRIPTION DESCRIPTION R262 7030003540 S.RESISTOR ERJ3GEYJ 682 V (6.8 kΩ) C401 4030008630 S.CERAMIC C1608 JF 1C 104Z-T-A R271 7030003640 S.RESISTOR ERJ3GEYJ 473 V (47 kΩ) C451 4030008630 S.CERAMIC C1608 JF 1C 104Z-T-A R272 7030003640 S.RESISTOR ERJ3GEYJ 473 V (47 kΩ) C452 4030008630 S.CERAMIC...
  • Page 22 [DISPLAY BOARD] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 1530002850 S.TRANSISTOR 2SC4116-BL (TE85R) IC1371 1180001530 IC PQ30RV31 1530002850 S.TRANSISTOR 2SC4116-BL (TE85R) IC1391 1180001250 S.IC TA7808F (TE16L) IC1401 1180001070 S.IC TA7805F (TE16L) IC1411 1110001400 S.IC µPC1555G2-T1 MCR10EZHJ 330 Ω (331) 7030000320 S.RESISTOR IC1601 1130007570 S.IC BU4094BCFV-E2 ERJ3GEYJ 221 V (220 Ω)
  • Page 23 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION D762 1790000620 S.DIODE MA77 (TX) L301 6200001830 S.COIL NL 322522T-100J D763 1790000620 S.DIODE MA77 (TX) L302 6200003020 S.COIL NL 322522T-R33J-3 D764 1790000620 S.DIODE MA77 (TX) L303 6200003010 S.COIL NL 322522T-R27J-3 D771 1790000620 S.DIODE MA77 (TX) L304 6200003020 S.COIL...
  • Page 24 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION ERJ3GEYJ 101 V (100 Ω) R261 7030003320 S.RESISTOR R732 7030003520 S.RESISTOR ERJ3GEYJ 472 V (4.7 kΩ) ERJ3GEYJ 101 V (100 Ω) ERJ3GEYJ 101 V (100 Ω) R281 7030003320 S.RESISTOR R733 7030003320 S.RESISTOR ERJ3GEYJ 101 V (100 Ω) ERJ3GEYJ 101 V (100 Ω) R301...
  • Page 25 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION ERJ3GEYJ 221 V (220 Ω) R883 7030003360 S.RESISTOR R1262 7030003550 S.RESISTOR ERJ3GEYJ 822 V (8.2 kΩ) R884 7030003510 S.RESISTOR ERJ3GEYJ 392 V (3.9 kΩ) R1263 7030003610 S.RESISTOR ERJ3GEYJ 273 V (27 kΩ) R885 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ)
  • Page 26 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION C223 4030007140 S.CERAMIC C1608 CH 1H 121J-T-A C401 4030011600 S.CERAMIC C1608 JB 1C 104KT-N C224 4030007130 S.CERAMIC C1608 CH 1H 101J-T-A C411 4030007080 S.CERAMIC C1608 CH 1H 390J-T-A C225 4030006850 S.CERAMIC C1608 JB 1H 471K-T-A C412 4030007130 S.CERAMIC C1608 CH 1H 101J-T-A...
  • Page 27 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION C882 4030011600 S.CERAMIC C1608 JB 1C 104KT-N C1365 4510004630 S.ELECTROLYTIC ECEV1CA100SR C891 4030011600 S.CERAMIC C1608 JB 1C 104KT-N C1371 4510005860 S.ELECTROLYTIC ECEV1HA2R2SR C892 4030006880 S.CERAMIC C1608 JB 1H 472K-T-A C1372 4030011600 S.CERAMIC C1608 JB 1C 104KT-N C893 4030006880 S.CERAMIC...
  • Page 28 [MAIN UNIT] [PLL UNIT] ORDER ORDER DESCRIPTION DESCRIPTION J884 6450001560 CONNECTOR PD-72 6150004250 COIL LS-471A (C-14922) J1081 6510007020 CONNECTOR TMP-J01X-V6 6200003170 S.COIL NL 322522T-330J J1221 6510018970 S.CONNECTOR B4B-PH-SM3-TB 6200003180 S.COIL NL 322522T-390J J1231 6510019970 S.CONNECTOR 52808-1090 6200003180 S.COIL NL 322522T-390J J1271 6510019190 S.CONNECTOR 52365-0891 6200001830 S.COIL...
  • Page 29 [PLL UNIT] [PLL UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ) R233 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ) 7030003480 S.RESISTOR ERJ3GEYJ 222 V (2.2 kΩ) R235 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ) ERJ3GEYJ 821 V (820 Ω) ERJ3GEYJ 101 V (100 Ω) 7030003430 S.RESISTOR R236...
  • Page 30 [PLL UNIT] [PLL UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 4030006930 S.CERAMIC C1608 CH 1H 020C-T-A 8970023350 M.OTHER RX2240 1.5DCOAXIAL (4)/PL C100 4030007080 S.CERAMIC C1608 CH 1H 390J-T-A C101 4030006880 S.CERAMIC C1608 JB 1H 472K-T-A C102 4030007020 S.CERAMIC C1608 CH 1H 120J-T-A 0910051124 PCB B 5274D C103...

  • Page 31: Display Unit

    SECTION 6 MECHANICAL PARTS AND DISASSEMBLY [CHASSIS PARTS] [DISPLAY UNIT] REF. NO. ODER NO. DESCRIPTION QTY. REF. NO. ODER NO. DESCRIPTION QTY. 6510000370 Connector MR-DS DS101 5030001690 LCD HLCF7395-012400 8930049630 LCD contact SRCN-2240-SP-N-W 8900007000 Cable OPC-684 8210016060 2240 Reflector 8900007000 Cable OPC-684 8930048880 2240 LCD Holder 8900007000 Cable OPC-684 8930049380 2240 LCD Filter...
  • Page 32 MP13 (C) MP382 (M) MP15 (C) MP13 (C) MP442 (M) MP9 (C) MP13 (C) MP15 (C) MP8 (C) MP15 (C) MP2 (C) MAIN UNIT EP2 (D) W6 (C) MP1 (D) MP20 (C) MP23 (C) J1 (C) MP3 (D) DISPLAY UNIT DS101 (D) MP13 (C) MP19 (C)
  • Page 33 SECTION 7 SEMI-CONDUCTOR INFORMATION • TRANSISTOR AND FET’S 2SA1576 R 2SC4081 R 2SC4116 BL 2SC4117 BL 2SC4405 3 (Symbol: FR) (Symbol: BR) (Symbol: LL) (Symbol: CL) (Symbol: OY3) 2SC4673 D 2SD1664 Q 2SK1740 2SK2171 4 2SK508 K52 (Symbol: CO) (Symbol: DA) (Symbol: IJ) (Symbol: KM) (Symbol: K52)

  • Page 34: Section 8 Board Layouts

    SECTION 8 BOARD LAYOUTS 8-1 PHONE AND VR BOARDS • PHONE BOARD TOP VIEW L121 C121 • VR BOARD R131 R141 J101 R143 J101 to LOGIC board J451 8 - 1...
  • Page 35 • PHONE BOARD BOTTOM VIEW ESPO ESPO ESPO J101 to LOGIC board J471 8 - 2...

  • Page 36: Display Board

    8-2 DISPLAY BOARD • TOP VIEW 8 - 3...
  • Page 37 • BOTTOM VIEW IC101 C101 DIMV COM4 COM3 COM2 COM1 J101 to LOGIC board J411 H5VL 8 - 4...

  • Page 38: Logic Board

    8-3 LOGIC BOARD R257 R256 R206 R255 R205 R254 R204 R253 R203 R252 R202 J411 R251 R201 R258 to DISPLAY board J101 R259 C103 C104 R231 C111 C112 DIMV C113 COM4 COM3 C114 COM2 COM1 C101 J521 J541 J501 J471 to MAIN unit J1541 to MAIN unit J1561 to MAIN unit J1521...

  • Page 39: Pll Unit

    8-4 PLL UNIT C116 C126 C117 R117 C151 C201 R180 R230 C128 Q151 Q201 C121 R151 C167 R201 C217 C120 C127 C323 IC201 IC151 R115 C324 L204 L205 R172 R222 C111 C152 C202 C123 R108 R110 C153 C155 C203 C205 R236 R178 R228...

  • Page 40: Main Unit

    8-5 MAIN UNIT J1231 J1221 L1291 IC1291 from optional unit IC1371 C1293 C1294 C1374 UT-106 C1296 R1258 R1259 C1372 C1373 C1352 D1351 [DC 1N] C1292 DAFO R1371 R1293 C1261 F1351 J1351 R1351 FUSE 3A D1371 R1374 F1353 R1236 R1235 R1233 R1231 F1352 C1262...

  • Page 41: Section 9 Block Diagram

    SECTION 9 BLOCK DIAGRAM OPTIONAL CHASSIS UNIT ANT1 (50 Ω) UT-106 UNIT Q472 ANT2 XP4311 DRES (450 Ω) DSPS R14V MDAT MDAT ATTC Q911 RX TOTAL GAIN ANTC SPST D711 MA77 2SK882 GR Q441 R898 D712 MA77 Q801 Q721 2SK1740 DSTB Q912 RV-150...

  • Page 42: Voltage Diagram

    SECTION 10 VOLTAGE DIAGRAM 10-1 FRONT UNIT LOGIC BOARD • DCK/DUD (At turn the main dial to the clockwise) IC351 M62354GP FRONT UNIT ETXD • DCK • BPCK (At beep on) VCC 16 C201 0.1 ERXD R271 47 k 4.8 V 4.8 V VDD 15 R211 1 k...
  • Page 43 DISPLAY BOARD • DCK/DUD (At turn the main dial to the clockwise) • DCK • BPCK (At beep on) 4.8 V 4.8 V R272 47 k R274 47 k R276 47 k 1 ms (2 ms) • COM0 R278 47 k 4.8 V •...
  • Page 44 SECTION 10 VOLTAGE DIAGRAM 10-1 FRONT UNIT LOGIC BOARD DISPLAY BOARD IC351 M62354GP • DCK/DUD (At turn the main dial to the clockwise) FRONT UNIT ETXD • DCK • BPCK (At beep on) VCC 16 C201 0.1 VDD 15 ERXD R271 47 k 4.8 V 4.8 V...

  • Page 45: Pll Unit

    10-2 PLL UNIT PLL UNIT TMP-P01X-A1 10 µH R110 4.4 V C104 R100 R111 C115 3.9 k 0.0047 4.9 V 0.0047 2.7 k C101 R102 0.0047 0.0047 68 nH 56 nH IC22 R103 0.5 V R151 UPB1509GV C108 R101 L153 0.0047 C102 MA77...

  • Page 46: Main Unit

    10-3 MAIN UNIT J1311 JPJ1044-01-010 MUTE ESPO ESPO ISPO ISPO EXT SP J1321 9.6 V 9.2 V PREAMP Off: 9.5 V HSJ0807-01-010 D151 L101 CP171 D371 D372 C101 L131 L132 C151 1SV265 L172 L173 C175 D172 C361 LR-233 0.1 µH 0.15 µH 4.7 µH MA77...
  • Page 47 ESPO ISPO 7.2 V 2.5 V R825 R816 FI761 Q801 2.7 V C724 L721 C726 D761 D763 NTCCM16083NH 681KC 2.7 k C841 2.7 V FL-272 D372 _ 5 V 22 P 10 µH 0.0047 MA77 MA77 2SC4081 R Q721 0.0047 MA77 L701 FI701...
  • Page 48 7.5 V L911 2.5 V R825 R816 7.4 V Q801 FI851 Q891 D851 D852 L891 L892 LS-450 D763 NTCCM16083NH 681KC 2.7 k C841 Q911 FL-65 R892 _ 5 V LS-450 LS-450 MA77 2SC4081 R MA77 MA77 3SK131 MAS 0.0047 2SK882 GR 7.7V R817 2.7 k...
  • Page 49 10-3 MAIN UNIT J1311 MUTE JPJ1044-01-010 ESPO ESPO ISPO ISPO EXT SP J1321 7.2 V 2.5 V R825 R816 FI851 7.4 V 7.5 V L911 HSJ0807-01-010 9.6 V D151 9.2 V PREAMP Off: 9.5 V 2.7 V D761 FI761 D763 Q801 2.7 k D851...
  • Page 50 08190 Sant Cugat del Valles Barcelona, SPAIN Phone : ( 93 ) 590 26 70 Fax : ( 93 ) 589 04 46 A Division of Icom America Inc. 3071 #5 Road, Unit 9, Richmond, B.C., V6X 2T4, Canada : http://www.icomspain.com...
  • Page 51 A-5580I-S 6-9-16, Kamihigashi, Hirano-ku, Osaka, 547-0002, Japan © 1999 by Icom Inc.

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