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Icom IC-703, Service Manual, Page: 5 / 77

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SECTION 2

INSIDE VIEWS

• DISPLAY BOARD

Sub CPU
(IC6: HD6473847RH)

+5V regulator

Main dial

Reset IC
(IC4: S-80945CLMC-G7F)

SW LED dimmer
 Q50: 2SB1132
 Q51: 2SC4081

LCD driver
(IC2: SED1522F0C)

VR board

Back light dimmer
 Q2: 2SB1132
 Q3: 2SC4081

Key dimmer
 Q13: 2SB1132
 Q14: 2SC4081

Sub CPU
(IC6: HD6433842RB27H)

+5V regulator

Main dial

Reset IC
(IC4: S-80945CLMC-G7F)

SW LED dimmer
 Q50: 2SB1132
 Q51: 2SC4081

LCD driver
(IC2: SED1522F0C)

VR board

Back light dimmer
 Q2: 2SB1132
 Q3: 2SC4081

Key dimmer
 Q13: 2SB1132
 Q14: 2SC4081

• PA UNIT

Expand IC
(IC600: ISPLSI2064VE)

Buffer
(IC560: NJM2904M)

Comparator
(IC640: TA75393)

Low-pass filter

TX/ RX switch
(RL250: ATN207)

Drive amplifier
(Q150: RD01MUS1)

Pre drive amplifier
(Q101: 2SK3074)

Power amplifier
(Q200, Q201:

(Q200, Q201: RD07MVS1)

 RD07MVS1)

Expand IC
(IC600: ISPLSI2064VE)

Buffer
(IC560: NJM2904M)

Comparator
(IC640: TA75393)

Low-pass filter

TX/ RX switch
(RL250: ATN207)

Drive amplifier
(Q150: RD01MUS1)

Pre drive amplifier
(Q101: 2SK3074)

Power amplifier
(Q200, Q201: RD07MVS1)

Summary of Contents for IC-703

Page 1: ...HF 50MHz ALL MODE TRANSCEIVER i703 SERVICE MANUAL...

Page 2: ...de back cover for your convenience REPAIR NOTES 1 Make sure a problem is internal before disassembling the transceiver 2 DO NOT open the transceiver until the transceiver is disconnected from its powe...

Page 3: ...4 1 4 2 PLL ADJUSTMENTS 4 2 4 3 TRANSMITTER ADJUSTMENTS 4 4 4 4 RECEIVER ADJUSTMENTS 4 8 4 5 SET MODE ADJUSTMENTS No 1 4 10 4 6 PA UNIT ADJUSTMENTS 4 12 4 7 SET MODE ADJUSTMENTS No 2 4 14 SECTION 5 P...

Page 4: ...odulation AM Low level modulation FM Variable reactance modulation Spurious emissions Below 30 MHz Less than 50 dB Above 30 MHz Less than 60 dB Carrier suppression More than 40 dB Unwanted sideband su...

Page 5: ...SC4081 LCD driver IC2 SED1522F0C VR board Back light dimmer Q2 2SB1132 Q3 2SC4081 Key dimmer Q13 2SB1132 Q14 2SC4081 PA UNIT Expand IC IC600 ISPLSI2064VE Buffer IC560 NJM2904M Comparator IC640 TA75393...

Page 6: ...rter IC6501 M62364FP Balanced modulator IC1801 TA4107F Automatic gain control circuit YGR amplifier IC101 PC2709T 1st mixer D701 HSB88WS 1st IF amplifier Q811 2SK508 1st IF filter FI851 FL 348 2nd mix...

Page 7: ...ER CIRCUIT MAIN UNIT The 1st mixer circuit mixes the receive signals with the 1st LO signal to convert the receive signal frequencies to a 64 455 MHz 1st IF signal The signals from the preamplifier ci...

Page 8: ...right column via the Tx Rx switch D1402 The filtered or bypassed signals are applied to the 2 ampli fiers Q1101 Q1201 and buffer amplifier Q1251 to obtain a detectable level at the demodulator circuit...

Page 9: ...reshold level set by the RF SQL control The RF SQL setting is picked up at the sub CPU DISPLAY board IC6 pin 97 The main CPU compares the S meter signal and RF SQL setting and controls the AF selector...

Page 10: ...n 8 The resulting signals from pin 9 are then applied to the buffer amplifier Q1721 via the analog switch IC1701 External modulation input from the ACC socket J6951 pin 11 is also applied to Q1721 Whi...

Page 11: ...F circuit amplifies the displayed frequency signal to obtain 10 W of RF output power for HF 50 MHz bands The HF 50 MHz RF signals from the 1st mixer D701 via the low pass filter pass through one of 8...

Page 12: ...fier IC2701 and applied to the ALC circuit as the reference voltage For the current APC the driving current at the power ampli fier is detected in the voltages IDH and IDL which appear at both termina...

Page 13: ...ers and is then applied to the 1st mixer D701 as a 1st LO signal 3 3 3 2ND LO AND REFERENCE OSCILLATOR CIRCUITS MAIN UNIT The reference oscillator IC9601 Q9621 X9501 generates a 64 MHz frequency used...

Page 14: ...l passes through the C646 to shift the its phase for 90 degrees The signal is applied to the phase detecting circuit L640 The output side signal is applied to the amplifiers Q643 Q811 The amplified si...

Page 15: ...5 regulator circuit IC5 Q10 Q11 D9 The out put voltage is applied to the SUB CPU IC6 LCD driver IC2 etc Line 8V 5V 3 5 3 VOLTAGE LINES DISPLAY BOARD 1 2 3 4 5 8 9 16 18 19 20 21 22 23 25 26 27 28 31...

Page 16: ...signal High While the speech compressor is ON Outputs 9600 bps packet mode control signal High While 9600bps packet mode is ON Outputs optional DSP unit control sig nal High While the DSP unit is ON...

Page 17: ...the phone plug is insert ed Input port for the RIT SUB key Input port for the main dial s A phase signal Input port for the main dial s B phase signal Input port for the sub dial s A phase signal Out...

Page 18: ...0 100 MHz Measuring range 0 to 5 kHz Frequency range At least 100 MHz Measuring range 0 100 Frequency range 1 kHz 10 Measuring range 1 100 Frequency range DC 100 MHz Measuring range 0 01 10 V Imput im...

Page 19: ...ay frequency 29 99999 MHz Mode USB Receiving Display frequency 60 00000 MHz Mode USB Receiving MAIN MAIN MAIN Connect an RF volt meter to check point CP9611 Connect a frequency counter to check point...

Page 20: ...ce frequency adjustment Reference frequency check point R9552 VCO2 lock voltage adjustment C9252 VCO1 lock voltage adjustment C9202 VCO1 and VCO2 lock voltage check point CP9151 CP9671 CP9611 MAIN UNI...

Page 21: ...nd set as 1 5 kHz 3 mV Transmitting Display frequency 14 10000 MHz Mode USB MIC GAIN 5 Connect an audio generator to MIC connector and set as 1 5 kHz 30 mV Transmitting Display frequency 52 00000 MHz...

Page 22: ...5 Transmit total gain adjustment R833 Id APC adjustment R2765 Transmit peak power adjustment R1203 R1203 Carrier suppression adjustment R1807 R1803 Output power adjustment R2705 R2706 MAIN UNIT TOP VI...

Page 23: ...k position Connect an audio generator to MIC connector and set as 1 kHz 30 mV Transmitting Display frequency 14 10000 MHz Mode CW RF POWER H KEY SPEED 60 BRK BK semi break in CW paddle n Connect an RF...

Page 24: ...4 7 FM deviation adjustment R2621 AM modulation adjustment R1811 R2618 R2707 CW carrier level adjustment R1853 MAIN UNIT TOP VIEW...

Page 25: ...FF Set an SSG as Frequency 14 15150 MHz Level 500 V 53 dBm and OFF Modulation OFF Receiving Display freq 14 15000 MHz Mode USB P AMP ATT Preamp ON NB ON Connect an SSG to the ANT con nector and set as...

Page 26: ...4 9 Receiver peak adjustment L1101 L1102 L1201 Receiver total gain adjustment R1203 Noise blanker adjustment L1052 L1053 L882 L881 MAIN UNIT TOP VIEW...

Page 27: ...PTT switch Transmit using an external PTT switch 1 1 2 3 1 1 2 3 4 5 6 1 2 3 4 5 6 S0 LEVEL S9 LEVEL 60dB LEVEL GO FILTER CAL CHK 10 W SET 5 W SET 2 5 W SET 1 W SET 0 5 W SET POmin CHK 10 W SET 5 W SE...

Page 28: ...smit using an external PTT switch Transmit using an external PTT switch Connect a 50 dummy load or power meter to ANT connector Connect a 50 dummy load or power meter to ANT connector 1 2 1 2 Push and...

Page 29: ...o ground Connect an audio generator to MIC connector and set as 1 5 kHz 30 mV Transmitting Transmitting PA Rear Panel PA Connect a digital multimeter to check point CP151 Connect a DC ammeter between...

Page 30: ...4 13 Idling current adjustment R159 R164 SWR detection check point CP41 SWR detection adjustment C561 J640 J642 J641 Antenna tuner adjustment plug replacement point PA UNIT TOP VIEW...

Page 31: ...to the following set ting or push UP DN to scroll the display Push MENU GO to set adjust ment value Push MENU GO to set adjust ment value Push MENU GO to set adjust ment value USB NOTE In case of not...

Page 32: ...SISTOR ERJ3GEYJ 471 V 470 R3 7030003400 S RESISTOR ERJ3GEYJ 471 V 470 R4 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R5 7030003340 S RESISTOR ERJ3GEYJ 151 V 150 R6 7030003440 S RESISTOR ERJ3GEYJ 102 V 1...

Page 33: ...YJ 821 V 820 R141 7030003430 S RESISTOR ERJ3GEYJ 821 V 820 R143 7030003800 S RESISTOR ERJ3GEYJ 105 V 1 M C1 4030006880 S CERAMIC C1608 JB 1H 472K T C2 4030006880 S CERAMIC C1608 JB 1H 472K T C4 403000...

Page 34: ...501 1160000070 S DIODE DAN202K T146 D520 1160000070 S DIODE DAN202K T146 A only D521 1160000070 S DIODE DAN202K T146 A only D560 1750000950 S DIODE MA732 TX D561 1750000950 S DIODE MA732 TX D562 17500...

Page 35: ...0 7030010820 S RESISTOR ERJ1TYJ 221U 220 R211 7030010820 S RESISTOR ERJ1TYJ 221U 220 R213 7030003500 S RESISTOR ERJ3GEYJ 332 V 3 3 k R214 7030003500 S RESISTOR ERJ3GEYJ 332 V 3 3 k R216 7030010810 S R...

Page 36: ...S RESISTOR ERJ3GEYJ 274 V 270 k R682 7030003610 S RESISTOR ERJ3GEYJ 273 V 27 k R683 7030003280 S RESISTOR ERJ3GEYJ 470 V 47 R684 7030003770 S RESISTOR ERJ3GEYJ 564 V 560 k R685 7030003440 S RESISTOR...

Page 37: ...4030006880 S CERAMIC C1608 JB 1H 472K T C83 4030011600 S CERAMIC C1608 JB 1E 104K T C84 4510004590 ELECTROLYTIC 16 MV 470 HC C85 4030011600 S CERAMIC C1608 JB 1E 104K T C86 4030006880 S CERAMIC C1608...

Page 38: ...8 JB 1H 472K T A only C533 4030006880 S CERAMIC C1608 JB 1H 472K T A only C534 4030006880 S CERAMIC C1608 JB 1H 472K T A only C540 4030011600 S CERAMIC C1608 JB 1E 104K T C541 4030011600 S CERAMIC C16...

Page 39: ...880 S CERAMIC C1608 JB 1H 472K T C866 4030006880 S CERAMIC C1608 JB 1H 472K T C867 4030006880 S CERAMIC C1608 JB 1H 472K T C868 4030006880 S CERAMIC C1608 JB 1H 472K T C869 4030006880 S CERAMIC C1608...

Page 40: ...1 1130003830 S IC TC7S04F TE85R IC5851 1130010520 S IC SN74HCT244APWR IC5901 1140011200 S IC M30620FCMGP IC5961 1130011210 S IC CAT24WC64J TE13 IC5981 1110005820 S IC R3112N281A TR IC6101 1130007700 S...

Page 41: ...03220 S TRANSISTOR 2SC4406 4 TL Q9401 1590001870 S TRANSISTOR DTA114EE TL A only Q9600 1560001260 S FET 2SK3018 T106 Q9621 1560000330 S FET 2SK210 GR TE85R Q9651 1530003150 S TRANSISTOR 2SC4673D TD Q9...

Page 42: ...018T R15J A only L526 6200005010 S COIL NL 252018T 100J A only L541 6200003240 S COIL NL 322522T 221J L542 6200003240 S COIL NL 322522T 221J L551 6200003260 S COIL NL 322522T 101J L552 6200002000 S CO...

Page 43: ...0 S RESISTOR ERJ3GEYJ 391 V 390 A only R502 7030003280 S RESISTOR ERJ3GEYJ 470 V 47 A only R503 7030004050 S RESISTOR ERJ3GEYJ 1R0 V 1 A only R504 7030003280 S RESISTOR ERJ3GEYJ 470 V 47 A only R505 7...

Page 44: ...00 R1344 7030003560 S RESISTOR ERJ3GEYJ 103 V 10 k R1361 7030003500 S RESISTOR ERJ3GEYJ 332 V 3 3 k R1362 7030003640 S RESISTOR ERJ3GEYJ 473 V 47 k R1363 7030003320 S RESISTOR ERJ3GEYJ 101 V 100 R1364...

Page 45: ...03440 S RESISTOR ERJ3GEYJ 102 V 1 k R2453 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R2454 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R2455 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R2456 7030003440 S RESI...

Page 46: ...03440 S RESISTOR ERJ3GEYJ 102 V 1 k R5807 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R5812 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R5814 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R5815 7030003440 S RESI...

Page 47: ...1 7030003720 S RESISTOR ERJ3GEYJ 224 V 220 k R9053 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 k R9054 7030003320 S RESISTOR ERJ3GEYJ 101 V 100 R9101 7030003800 S RESISTOR ERJ3GEYJ 105 V 1 M R9102 70300034...

Page 48: ...C593 4030007150 S CERAMIC C1608 CH 1H 151J T C594 4030007140 S CERAMIC C1608 CH 1H 121J T C595 4030011340 S CERAMIC C1608 CH 1H 471J T C596 4030007170 S CERAMIC C1608 CH 1H 221J T C601 4030006880 S CE...

Page 49: ...40 S CERAMIC C1608 CH 1H 471J T C1701 4510004630 S ELECTROLYTIC ECEV1CA100SR C1702 4030011600 S CERAMIC C1608 JB 1E 104K T C1703 4030012610 S CERAMIC C2012 JB 1C 474K T C1721 4510004440 S ELECTROLYTIC...

Page 50: ...30006880 S CERAMIC C1608 JB 1H 472K T C6703 4030006880 S CERAMIC C1608 JB 1H 472K T C6704 4030006880 S CERAMIC C1608 JB 1H 472K T C6751 4030006880 S CERAMIC C1608 JB 1H 472K T C6752 4030006880 S CERAM...

Page 51: ...0004630 S ELECTROLYTIC ECEV1CA100SR C9502 4030011600 S CERAMIC C1608 JB 1E 104K T C9503 4030006880 S CERAMIC C1608 JB 1H 472K T C9504 4030006880 S CERAMIC C1608 JB 1H 472K T C9521 4030006980 S CERAMIC...

Page 52: ...THER SX2591 Shield B 1 MA EP2 0910055866 PCB B 5904F EP101 6910012350 S BEAD MMZ1608Y 102BT EP801 6910012350 S BEAD MMZ1608Y 102BT EP812 6910012350 S BEAD MMZ1608Y 102BT EP831 6910012350 S BEAD MMZ160...

Page 53: ...33 8510015060 2591 shield plate 1 MP35 8930060140 Sheet CI 1 MP36 8930060140 Sheet CI 1 MP38 8930060310 Shield tape P 1 MP39 8930060300 Shield tape O 1 MP40 8930060290 Shield tape N 1 CHASSIS UNIT ORD...

Page 54: ...9702 8930059930 Sponge HG 1 MP9703 8930045530 Magic tape F 1 MP9704 8930060170 Rubber sheet BE 1 MP9705 8930060180 Rubber sheet BF 1 MP9961 8510015390 2591 reg plate 1 MAIN UNIT ORDER NO REF NO DESCRI...

Page 55: ...T RF SQL CH VFO A PO S1 5 5 3 7 9 20 40 10 60dB USB M1 SPL A B A B MP25 C MP20 C MP4 C MP12 C MP14 C J1 C MP8 C MP18 F MP12 F MP21 F MP11 C MP11 C MP22 C MP28 C J2 D MP10 C MP26 F MP11 F MP3 F MP24 C...

Page 56: ......

Page 57: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan S 13912HZ C1 C 2003 Icom Inc...

Page 58: ...D MP3 F DS4 D EP7 D DS5 D J2 D R2 VR W1 F MP15 F MP7 F VR BOARD R1 VR S1 VR SP1 C MP21 C MP29 C MP9700 M MP9625 M MP9624 M MP30 C MP9701 M MP9702 M MP5901 M WS1 M MP701 M MP9621 M MP15 C MAIN UNIT PA...

Page 59: ...E Symbol UW Symbol UV Symbol KD Symbol 14 Symbol 14 Symbol 24 Symbol JA Symbol K2 Symbol RD07MVS1 Symbol K1 Symbol 9U Symbol 3X B C E B C E B C E B C E B E C B E C B E C B E C B C E D G S S D G D G S...

Page 60: ...ARD LAYOUTS 8 1 DISPLAY BOARD TOP VIEW POWER P AMP ATT TUNER CALL RIT SUB MENU F 1 F 2 F 3 PHONES LOCK DISPLAY TS MODE LRXD 1 7 2 8 to MAIN unit J5101 J1 LTXD 8V AFO GND MIC MICE PWRK 8 1 8 2 JACK BOA...

Page 61: ...J1 U D AF PTT MICEL MICL GND SQLS DN 1 to VR board J1 13 2 12 J3 AFL SQL AFV UP SFT GND AFL AF AF AFS AFS 5V PWRK to DISPLAY board MICE MIC GND AFO 8V LTXD LRXD AF RF SQL M CH SHIFT SPEAKER PHONES 13...

Page 62: ...DRES MDT3 TDTS IDL GND LRXD 7 1 8 to JACK board J1 2 J5101 LTXD 8V AFO GND MIC MICE PWRK DRES 10 2 to UT 106 9 1 J2453 DSTB MCK DSPS GND DINT MDT 5V GND GND MSST 1 7 2 to Optional unit UT 102 8 J7121...

Page 63: ...1 8 16 9 1 10 6 1 5 7 14 8 1 4 8 5 1 1 1 1 8 16 9 1 1 1 7 14 8 8 16 9 7 14 8 7 14 8 7 14 8 7 14 8 1 1 4 8 5 8 4 1 5 7 14 8 6 10 5 1 8 16 9 1 1 7 14 8 1 12 24 13 16 9 1 8 BOTTOM VIEW MAIN UNIT 8 4...

Page 64: ...unit J1 RX P4 P5 ANT CHASSIS J1 GND 1 17 2 18 to MAIN unit J6751 J41 TSWL TPHK REFL GND MCK3 PWRS TOE IDH TGK TPZS TPZL FORL DRES MDT3 TDTS IDL GND START 1 17 2 18 to MAIN unit J6701 J1 TPWR POWS GND...

Page 65: ...BOTTOM VIEW PA UNIT 8 6...

Page 66: ...VCO REG P8V IC9681 TA78L05F 2nd PLL REG Q9681 2SC4081 2nd VCO REG 8V PSS DIN AMP IC2201 NJM2058M AMP IC2201 NJM2058M DET D2221 1SS385 Q6201 DTC114EE SW UNLK Q9801 XP4311 D9801 DAP222 SW UNLK Q6342 2SB...

Page 67: ...72 J7121 J6751 J6801 8V MUDL AFO SEND MICE MIC SQLS 6 4 2 1 3 5 J6851 CIV NC CIVE J6901 DASK J6921 DOTK GND 4 3 2 1 8 7 6 5 12 11 10 9 13 J6951 DATA to microphone REMOTE KEY ACC EXT SP SEND BDT ISPO E...

Page 68: ...ATTD TUND SUBD RITD Q18 XP4111 R5 150 Q1 DTC114EE C33 0 0047 R30 1k C32 0 0047 C31 0 0047 W1 C7 0 0047 L1 100 D5 MA2S111 D6 MA2S111 R42 1k R46 2 2k R44 3 3k R47 47k R45 3 3k C8 0 0047 C9 0 0047 D7 DA...

Page 69: ...R416 47k R412 1k PRES Q415 2SK3018 TXH TXL Q411 DTA114EE R415 47k Q414 2SK3018 Q410 DTA114EE R414 47k R410 1k R411 1k PROL PROS 3V 3V 14V 5V C510 39p C511 0 0047 R505 270 L508 10 D502 MA77 D601 MA77...

Page 70: ...7k C1321 0 1 O I FI1301 FL 65 R1323 100 C1322 0 1 R1324 10k D1311 MA77 R1006 680 NBLV C1341 0 1 D1305 MA77 R1341 10k FI1341 CFWS455G C1342 0 1 2F80 R1342 47k R1343 100 I O R1344 10k D1313 MA77 C1361 0...

Page 71: ...1k D2221 1SS385 C2221 0 1 R2221 100k C2222 0 1 R2222 100k R2224 100k 13 14 12 IC2201 NJM2058M R2223 150k R2208 1k R2209 1k OVDK V GND 4 11 IC2201 NJM2058M C2204 0 1 VDD IC2301 BU4052BCF 2 1 3 X2 X1 X...

Page 72: ...010 1k R6012 1k R6013 1k C6001 0 0047 R6002 47k C6006 0 0047 C6008 0 0047 C6007 0 0047 R6005 10k D6001 MA2S111 B0 B5 B6 B7T B7R C6101 0 1 R6151 1k C6151 0 0047 DRES PCK PDT PMST PDST PBST _P2ST UNLK P...

Page 73: ...02 12p C9401 27p C9403 33p L9403 68n C9404 4p C9407 68p C9408 120p L9404 0 22 C9405 18p C9409 68p R9403 18 R9402 270 R9404 270 1LO C9681 10 R9681 10k IC9681 TA78L05F C9682 10 C9683 0 1 C9684 0 1 C9685...

Page 74: ...OTK EP6922 EP6921 C6851 0 001 C6852 0 001 C6853 0 001 C6854 0 001 C6855 0 001 Q6851 2SK3018 R6853 47k R6852 1k SQSS DOUT AFO DIN C6856 1 C6962 1 AAF 4 3 2 1 8 7 6 5 12 11 10 9 13 J6951 L6953 BM27 400...

Page 75: ...00p D520 DAN202K D521 DAN202K C502 27p C513 0 0047 C506 18p RL501 ATX222 C511 0 0047 C505 68p C512 0 0047 L501 LR 426 L500 LR 426 C510 0 0047 C507 68p D500 DAN202K W500 W501 RL500 ATX222 D501 DAN202K...

Page 76: ...8R_ C8S_ C817 0 0047 C8S C816 0 0047 R839 1k C9R R836 1k R837 47k R838 47k Q809 UM5K1N C9R_ C9S_ C819 0 0047 C9S C818 0 0047 R843 1k C0R R840 1k R841 47k R842 47k Q810 UM5K1N C0R_ C0S_ C821 0 0047 C0S...

Page 77: ...D641 1SS355 RL640 AHY107 C643 0 0047 Q640 2SK3018 R681 270k C669 0 001 R680 10k C671 0 1 C670 0 001 R679 270k R678 10k Q642 2SK3018 C645 0 0047 D647 1SS355 C661 0 0047 RL641 AHY107 W644 L645 10 C664 0...

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