Icom IC-M72 Service Manual

Vhf marine transceiver

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Instruction manual (40 pages)

Instruction manual (40 pages)

Instruction manual (20 pages)

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Questions and answers

Robert Savell

January 22, 2025

Sound does not work

1 comments:

Mr. Anderson

February 10, 2025

The sound might not work on the Icom IC-M72 due to the following reasons:

1. Squelch Level: The squelch level may be set too high, which blocks audio. Adjust it by pushing the appropriate buttons (`[ ]`, `[Y]`/`[Z]`) to lower the squelch level.

2. Volume Setting: The volume may be set too low. Rotate the `[VOL]` knob to increase the volume.

3. Signal Reception: Ensure the radio is receiving a signal. The " " indicator should appear when a signal is being received, and audio should emit from the speaker.

4. Speaker Issue: Check if the speaker is functioning properly. If the external speaker or audio output is faulty, repair or replacement may be needed.

5. Incorrect Channel: Verify that the correct channel is selected, as some channels may not have active transmissions.

If these adjustments do not resolve the issue, further inspection or servicing may be required.

This answer is automatically generated

Summary of Contents for Icom IC-M72

Page 1 �� VHF MARINE TRANSCEIVER iC-m72 S-14221MZ-C1 Jan. 2006...
Page 2 8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver. Icom, Icom Inc. and logo are registered trademarks of Icom Incorporated (Japan) in the United States, the United Kingdom, Germany, France, Spain, Russia and/or other countries.
Page 3: Table Of Contents
TABLE OF CONTENTS SECTION 1 SPECIFICATIONS SECTION 2 INSIDE VIEWS SECTION 3 DISASSEMBLY INSTRUCTIONS SECTION 4 CIRCUIT DESCRIPTION 4 - 1 RECEIVER CIRCUITS ....................4 - 1 4 - 2 TRANSMITTER CIRCUITS .................... 4 - 2 4 - 3 PLL CIRCUITS ........................ 4 - 3 4 - 4 OTHER CIRCUITS ......................
Page 4: Specifications
• Antenna impedance • Operating temperature range −20˚C to +60˚C; −4˚F to +140˚F • Power supply requirement Speciﬁ ed Icom's battery pack only (operating volage 7.5 V DC; negative ground) • Current drain (approx.) 0.4 A (internal speaker) RX (Max. audio) 0.2 A (external speaker)
Page 5 • CHANNEL LISTS . y l , s l y l l c i l 1 - 2...
Page 6: Main Unit
SECTION 2 INSIDE VIEWS • MAIN UNIT (Top view) �� ...
Page 7 SECTION 3 DISASSEMBLY INSTRUCTIONS 3 Removing the RF unit 1 Removing the chassis panel q Unscrew 3 screws F. q Unscrew 2 screws A and 4 screws B. w Unsolder 7 points G and remove the RF unit. w Disconnect the speaker cable C and remove the chassis from the front pannel.
Page 8: Circuit Description
SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVE CIRCUITS 4-1-3 1st IF CIRCUITS (RF UNIT) The received signals are converted into the 1st IF signal, 4-1-1 ANTENNA SWITCH (RF UNIT) and amplified at the 1st IF circuits. The received signals from the antenna connector are passed through the antenna switch which toggles the The amplified received signals from the RF circuits are applied receive (RX) line and transmit (TX) line.
Page 9: Transmitter Circuits
4-1-5 AF CIRCUITS (MAIN UNIT) 4-2 TRANSMIT CIRCUITS The demodulated AF signals from the demodulator circuits are 4-2-1 MICROPHONE AMPLIFIER CIRCUITS (MAIN UNIT) ampliﬁ ed and ﬁ ltered in AF ampliﬁ er circuits. The AF signals from the microphone (MIC signals) are ﬁ...
Page 10: Pll Circuits
4-2-3 TRANSMIT AMPLIFIERS (RF UNIT) 4-3 PLL CIRCUITS The VCO output signal is ampliﬁ ed to transmit output power 4-3-1 VCO CIRCUIT (RF UNIT) level by the transmit ampliﬁ ers. The VCO (Q21, Q22, D21−D23) generates the both of trans- mit signal and LO signals for the 1st IF conversion.
Page 11: Other Circuits
4-4 OTHER CIRCUIT 4-6 PORT ALLOCATIONS 4-4-1 VOX CIRCUIT (MAIN UNIT) 4-6-1 CPU (MAIN UNIT; IC360) The VOX circuit toggles TX and RX automatically by detect- Port ing voice signals from the microphone. Description Name BEEP Outputs beep sound to the AF circuits. The MIC signals from the external microphone are applied to the VOX amplifier (IC431, pins 1, 2).
Page 12 4-6-1 CPU (MAIN UNIT; IC360)-continued 4-6-2 D/A CONVERTER (RF UNIT; IC190) Port Port Description Description Name Name MODC Outputs deviation adjust signal. BTYPE Input port for battery type detect signal. FCON Outputs reference frequency adjust signal. Outputs MIC mute signal to the AF mute switch PCON Outputs transmit power setting voltage.
Page 13: Adjustment Procedures
, and click the program group 'CS-M72 ADJ’ in the ‘Programs’ folder of the [Start] menu, then CS-M72 ADJ’s window appears. (4) Click ‘Adjust’ on the CS-M72’s window, then IC-M72’s up-to-date condition appears. (5) Set or modify adjustment value as specified.
Page 14 RF power meter 0.1–10 W/50 Ω To SP line (RED) SINAD meter Frequency JIG cable counter OPC-1028 Speaker (8 Ω) IC-M72 To SINAD meter/speaker To audio generator/AC millivoltmeter Ω 33 k OPC-478/U WHITE (EXTMIC) (MIC line) OPC-1028 RED (AFOUT) (SP line)
Page 15 • PC SCREEN EXAMPLE I/O check button NOTE: The above screen is an example. Each transceiver has its own specific values for each setting. q: Adjustment condition t: Receive sensitivity (Automaticaly) w: Reference frequency y: Receive sensitivity (Manualy) e: Transmit output power u: Squelch level r: FM deviation i: VOX...
Page 16: Software Adjustment
5-2 SOFTWARE ADJUSTMENT (FREQUENCY) Select the adjustment item with [↑] / [↓] keys, then set the value with [←] / [→] keys on the connected PC. MEASUREMENT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT OPERATION PLL LOCK 1 • Operating CH. : 16 Click the "I/O check button"...
Page 17 5-3 SOFTWARE ADJUSTMENT (RECEIVE AND TRANSMIT) Select the adjustment item with [↑] / [↓] keys, then set the value with [←] / [→] keys on the connected PC. NOTE: "RECEIVE SENSITIVITY" should be adjusted before "SQUELCH LEVEL," or "SQUELCH LEVEL" will not be adjusted properly.
Page 18: Parts List
SECTION 6 PARTS LIST [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION LOCATION LOCATION R234 7030007300 S.RES ERJ2GEJ 332 X (3.3 k 34.8/9.7 IC170 1110003201 S.IC TA31136FNG (EL) 52/32.6 R235 7030005930 S.RES ERJ3GEYF 334 V (330 k 32.8/13.5 IC200 1110003780 S.IC NJM2902V-TE1 25.1/32.2 R236...
Page 19 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION LOCATION LOCATION R415 7030005090 S.RES ERJ2GEJ 104 X (100 k C266 4030016950 S.CER ECJ0EB1A473K 30.3/37.7 [scramble] only B 32/18.6 C267 4030018860 S.CER ECJ0EB0J105K 30/36.5 R416 7030005160 S.RES ERJ2GEJ 105 X (1 M C280 4030018860 S.CER ECJ0EB0J105K 16.1/28.4...
Page 20 [RF UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION LOCATION LOCATION FI150 2030000350 MLH 21R15AB (FL-368) MC250 7700002480 MIC SKB-2746 LPC FI151 2030000270 MLH FL-363 (21.7 MHz) EP360 8930069010 LCT SRCN-2905-SP-N-W 6050011740 S.XTL CR-766 (21.250 MHz) 6.3/36.8 6200008070 S.COL MLF1608E 6R8K 6.8U 3.8/37.6 6200011021 S.COL ELJRF 82NJFB 11.5/36.7...
Page 21 [RF UNIT] [RF UNIT] ORDER ORDER DESCRIPTION DESCRIPTION LOCATION LOCATION 7030005220 S.RES ERJ2GEJ 223 X (22 k 22/17.2 4030017530 S.CER ECJ0EC1H0R5B 16.1/29.1 7030005050 S.RES ERJ2GEJ 103 X (10 k 21.7/16 4030017460 S.CER ECJ0EB1E102K 10.8/27.1 7030005110 S.RES ERJ2GEJ 224 X (220 k 4030017630 S.CER ECJ0EC1H120J 10.8/29.2 Except [AUS] T...
Page 22: Mic Board
[RF UNIT] • BC-166 [MAIN UNIT] ORDER DESCRIPTION LOCATION ORDER DESCRIPTION LOCATION C225 4030007020 S.CER C1608 CH 1H 120J-T 21.9/4.4 C226 4030017610 S.CER ECJ0EC1H090C 27.6/5.3 1190002270 S.IC NJW4100V-TE1 47.3/19.4 C380 4030017460 S.CER ECJ0EB1E102K 27.7/20.4 C381 4030017460 S.CER ECJ0EB1E102K 25.9/30.4 C510 4030017460 S.CER ECJ0EB1E102K 1.5/3 1540000471 S.TR...
Page 23 SECTION 7 MECHANICAL PARTS AND DISASSEMBLY [CHASSIS PARTS] [RF UNIT] REF. NO. ORDER NO. DESCRIPTION QTY. REF. NO. ORDER NO. DESCRIPTION QTY. 6910017840 2905 ANT connector S250 2260002800 SW-167 (SKQT) 6510025340 2905 contact spring <AI> S328 2260002800 SW-167 (SKQT) 8900010960 OPC-1129 6910014690 MPZ1608S221A...
Page 24 �� ...
Page 25 SECTION 8 SECTION PARTS LIST SEMICONDUCTOR INFORMATION 8 - 1 TRANSISTORS AND FET'S 8 - 2 DIODES NAME SYMBOL INSIDE VIEW NAME SYMBOL INSIDE VIEW NAME SYMBOL INSIDE VIEW � � � KTA2015Y-RTK/P � 2SB1201S-TL B1201 � � � � 1SV307 �...
Page 26 The combination of this page and the next page shows SECTION 9 BOARD LAYOUTS the unit layout in the same configuration as the actual P.C. Board. �� ...
Page 27 The combination of this page and the previous page shows the unit layout in the same configuration as the actual P.C. Board. �� ...
Page 28 SECTION 10 BLOCK DIAGRAM �� ...
Page 29 SECTION 11 VOLTAGE DIAGRAM �� ...
Page 30 �� ...
Page 31 SECTION 12 BC-166 INFORMATION • BC-166 VOLTAGE DIAGRAM • BC-166 CHARGER PARTS LIST MECHANICAL PARTS �� CHASSIS PARTS REF. NO. ORDER NO. DESCRIPTION QTY. � � �� ...
Page 32 �� ...

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Parts List