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Kenwood TM-481A Service Manual
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Kenwood TM-481A Service Manual

430mhz fm transceiver
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430MHz FM TRANSCEIVER
TM-481A
SERVICE MANUAL
Knob (VOL)
(K29-9498-03)
Modular jack (MIC)
(E58-0535-05)
DISASSEMBLY FOR REPAIR .....................2
CIRCUIT DESCRIPTION .............................5
COMPONENTS DESCRIPTION ..................9
SEMICONDUCTOR DATA .........................11
PARTS LIST ...............................................12
EXPLODED VIEW ......................................18
PACKING ...................................................19
ADJUSTMENT ...........................................20
This product complies with the
RoHS
4
Key top
(K29-9497-01)
CONTENTS
directive for the European market.
© 2011-12 PRINTED IN JA PAN
B53-7001-00 ( Y ) 63
Knob (ENC)
Panel assy
(K29-9499-03)
(A62-1189-03)
TERMINAL FUNCTION .............................29
TX-RX UNIT (X57-8130-24) ....................30
SCHEMATIC DIAGRAM ............................36
BLOCK DIAGRAM .....................................40
LEVEL DIAGRAM ......................................42
SPECIFICATIONS .................. BACK COVER
This product uses Lead Free solder.

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  • Page 1: Table Of Contents

    430MHz FM TRANSCEIVER TM-481A SERVICE MANUAL © 2011-12 PRINTED IN JA PAN B53-7001-00 ( Y ) 63 Knob (VOL) Knob (ENC) Panel assy (K29-9498-03) (K29-9499-03) (A62-1189-03) Modular jack (MIC) Key top (E58-0535-05) (K29-9497-01) CONTENTS DISASSEMBLY FOR REPAIR .....2 TERMINAL FUNCTION ......29 CIRCUIT DESCRIPTION ......5...

  • Page 2: Disassembly For Repair

    Copyright 2011 by JVC KENWOOD Corporation. All While every precaution has been taken in the preparation rights reserved. of this manual, JVC KENWOOD Corporation assumes no No part of this manual may be reproduced, translated, responsibility for errors or omissions. Neither is any liability...
  • Page 3 TM-481A DISASSEMBLY FOR REPAIR 3. Disconnect the fl at cable from the connector of the panel 5. When removing the TX-RX PCB, fi rst remove the solder of assembly. the antenna hot pin and positive terminal of the DC cord.
  • Page 4 TM-481A DISASSEMBLY FOR REPAIR 6. Pull it out behind the chassis by rotating the bush ③ of 2. When mounting the panel assembly, pass the fl at cable the DC cord 90 degrees in the direction of the arrow after through the hole of the chassis as shown below, then con- the screw ①...

  • Page 5: Circuit Description

    TM-481A CIRCUIT DESCRIPTION ■ IF Amplifi er Frequency Confi guration The fi rst IF signal is amplifi ed by Q503, and then goes to The receiver utilizes double conversion. The first IF is IC501 (FM processing IC). The signal is heterodyned again 49.95MHz and the second IF is 450kHz.
  • Page 6 TM-481A CIRCUIT DESCRIPTION ■ Wide/Narrow Switching Circuit ■ Squelch Circuit The Wide port (pin 65) and Narrow port (pin 64) of the The detection output from the FM IC (IC501) passes MCU is used to switch between ceramic fi lters. When the through a noise amplifier (Q502) to detect noise.
  • Page 7 TM-481A CIRCUIT DESCRIPTION ■ Unlock Circuit Transmitter System During reception, the 8RC signal goes high, the 8TC ■ Outline signal goes low, and Q708 turns on. Q710 turns on and a The transmitter circuit produces and amplifi es the desired voltage is applied to 8R.
  • Page 8 TM-481A CIRCUIT DESCRIPTION Control Circuit ■ Key Matrix Circuit The MCU carries out the following tasks (See Fig. 10.): The front panel has function keys. Each of them is con- 1) Controls the WIDE, NARROW, and TX/RX outputs. nected to a cross point of a matrix of the KI1 to KI3 and KSI 2) Controls the display circuit.

  • Page 9: Components Description

    TM-481A CIRCUIT DESCRIPTION voltage, the INT voltage detector IC (IC712) will set to high ■ D/A Converter on MCU port 18 (INT) if B line becomes less than approxi- mately 9.5V. The MCU will then send the backup data to the The D/A converter (IC705) is used to adjust the MO mod- EEPROM (IC708) and enter stop mode.
  • Page 10 TM-481A COMPONENTS DESCRIPTION Ref. No. Use / Function Operation / Condition / Compatibility Ref. No. Use / Function Operation / Condition / Compatibility Oscillator RX VCO VCO frequency control T/R switch On when RX VCO frequency Oscillator TX VCO control...

  • Page 11: Semiconductor Data

    TM-481A SEMICONDUCTOR DATA MCU: 30622MEP594GU (TX-RX unit IC707) Pin No. Name Function Pin No. Name Function TONE CTCSS/DCS output Common data DTMF DTMF/BEEP/1750Hz output Common clock PLLE PLL IC chip select Not used Not used DST1 Destination 1 57~59 DST2~DST4...

  • Page 12: Parts List

    TM-481A PARTS LIST New Parts. indicates safety critical components. L : Scandinavia K : USA P : Canada Parts without Parts No. are not supplied. Y : PX (Far East, Hawaii) T : England E : Eu rope Les articles non mentionnes dans le Parts No. ne sont pas fournis.
  • Page 13 TM-481A PARTS LIST TX-RX UNIT (X57-8130-24) Desti- Desti- Ref. No. Ad dress Parts No. Description Ref. No. Ad dress Parts No. Description parts nation parts nation C404 C93-0552-05 CHIP C 2.0PF C560 CC73HCH1H010B CHIP C 1.0PF C405,406 C93-0603-05 CHIP C...
  • Page 14 TM-481A PARTS LIST TX-RX UNIT (X57-8130-24) Desti- Desti- Ref. No. Ad dress Parts No. Description Ref. No. Ad dress Parts No. Description parts nation parts nation C772 CK73HB1E104K CHIP C 0.10UF C910 CK73HB1H102K CHIP C 1000PF C774 CK73HB1H182K CHIP C...
  • Page 15 TM-481A PARTS LIST TX-RX UNIT (X57-8130-24) Desti- Desti- Ref. No. Ad dress Parts No. Description Ref. No. Ad dress Parts No. Description parts nation parts nation L77-1944-05 TCXO(16.8MHZ) R377,378 RK73HB1J103J CHIP R 1/16W X701 L78-1427-05 RESONATOR(8.00MHZ) R380 R92-1061-05 JUMPER REST...
  • Page 16 TM-481A PARTS LIST TX-RX UNIT (X57-8130-24) Desti- Desti- Ref. No. Ad dress Parts No. Description Ref. No. Ad dress Parts No. Description parts nation parts nation R717 RK73HB1J183J CHIP R 1/16W R795 RK73GH2A562D CHIP R 5.6K 1/10W R718 RK73HB1J152J CHIP R 1.5K...
  • Page 17 TM-481A PARTS LIST TX-RX UNIT (X57-8130-24) Desti- Desti- Ref. No. Ad dress Parts No. Description Ref. No. Ad dress Parts No. Description parts nation parts nation 1SV278F VARIABLE CAPACITANCE DIODE Q506 2SK1830F DA2S101 DIODE Q701-703 2SC4919-S TRANSISTOR D9 ,10 HSC277...

  • Page 18: Exploded View

    TM-481A EXPLODED VIEW A : N35-2604-43 B : N67-3008-48 C : N80-2008-48 D : N87-2608-48 IC302 IC715 TX-RX unit (A/2) TX-RX section R380 X57 A/2 X57 A/2 J701 TX-RX unit (B/2) Display section Parts with the exploded numbers larger than 700 are not supplied.

  • Page 19: Packing

    TM-481A PACKING 713 Protection bag 715 Packing fixture 37 Microphone (T91-0641-75) 710 Protection bag 716 Packing fixture 17 Fuse (Blade type) 15A (F52-0024-05) 26 Holder (MIC) 14 DC cord (J19-1584-15) (E30-7744-05) 34 Screw set (N99-2082-05) 28 Bracket (J29-0726-03) 717 Item carton case...

  • Page 20: Adjustment

    TM-481A ADJUSTMENT Measuring Equipment for Alignment Preparation 1. Digital voltmeter (DVM) • Set the controls and switches to the positions listed below unless otherwise specifi ed. Input impedance: High Volume control : Fully counterclockwise 2. RF voltmeter (RF VM) Power switch : OFF Input impedance: 1M...
  • Page 21 TM-481A ADJUSTMENT ■ Panel Key Operation Method in Adjustment Mode Adjustment Mode This mode is used to replace or readjust the EEPROM (IC708). In Adjustment Mode, the transceiver can be adjusted us- ing its panel keys. ■ Items that can be adjusted in Adjustment Mode 1.
  • Page 22 TM-481A ADJUSTMENT Adjustment Transmit Receive Adjustment Item Display Note Signaling Frequency Point (MHz) (MHz) Frequency Tune Center 435.100 435.050 400.100 400.050 Low’ 417.500 417.550 TX High Power Center “H” icon appear 435.100 435.050 High’ 452.500 452.550 High 469.900 469.950 400.100 400.050...
  • Page 23 TM-481A ADJUSTMENT Adjustment Points Mkr1 400.1 MHz Ref -20 dBm Atten 5 dB -60.05 dBm Peak Source Amptd TX-RX UNIT (X57-8130-24) (A/2) -30.00 dBm : TX-RX section Component side W1 S2 S3 FC Center 400.1 MHz Span 200 MHz #Res BW 100 kHz...
  • Page 24 TM-481A ADJUSTMENT Common Section Measurement Adjustment Item Condition Specifi cations / Remarks Test- Unit Terminal Unit Parts Method equipment 1. Setting 1) Power supply voltage DC power supply terminal : 13.8V 2. All LCD 1) All LCD segments light check Confi...
  • Page 25 TM-481A ADJUSTMENT Measurement Adjustment Item Condition Specifi cations / Remarks Test- Unit Terminal Unit Parts Method equipment 3. Low power 1) Adj item: [LPL .] Power Rear Front Write 25W±1W uning [Low] Adjust: [ meter panel panel control 2) Transmit [Low’]...
  • Page 26 TM-481A ADJUSTMENT Measurement Adjustment Item Condition Specifi cations / Remarks Test- Unit Terminal Unit Parts Method equipment 6. MIC 1) Frequency: 435.100MHz Linear Rear Check ±1.2~1.9kHz sensitivity AG: 1kHz/5.4mV detector panel (Narrow) Detector: P-P/2 Oscilloscope LPF: 15kHz HPF: OFF Front...
  • Page 27 TM-481A ADJUSTMENT Receiver Section (Refer to the Table 1 on page 22 for the frequencies which will apply in the adjustment mode.) Measurement Adjustment Item Condition Specifi cations / Remarks Test- Unit Terminal Unit Parts Method equipment 1. Band Pass 1) Adj item: [BPL.]...
  • Page 28 TM-481A ADJUSTMENT Measurement Adjustment Item Condition Specifi cations / Remarks Test- Unit Terminal Unit Parts Method equipment 3. Squelch 1) Adj item: [SQOL.] Rear Front Tuning Write Open 2) SSG output Oscilloscope panel panel control : –124dBm (0.14µV) • Wide...

  • Page 29: Terminal Function

    TM-481A TERMINAL FUNCTION TX-RX unit (X57-8130-24 A/2) TX-RX unit (X57-8130-24 B/2) : TX-RX Section : Display Section Pin No. Name Function Pin No. Name Function CN702 CN901 SPGND AF GND SPGND AF GND SPGND AF GND SPGND AF GND SPOUT...

  • Page 30: Pc Board

    TM-481A PC BOARD TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION Component side view (J79-0316-19 A/2) F701 C826 R821 R820 C828 C833 Q713 R336 C338 Q707 D712 D710 C815 TEMP1 L708 R762 IC712 R756 Q703 TEMP2 L709 Q702 C863 C766 C764 X701...
  • Page 31 TM-481A PC BOARD TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION Component side view (J79-0316-19 A/2) Ref. No. Address IC302 IC303 IC707 IC302 IC708 IC711 6G IC712 IC715 C418 Q502 11N C417 Q506 Q702 D313 Q703 C422 R378 Q704 C416 Q705 L312...
  • Page 32 TM-481A PC BOARD TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION Foil side view (J79-0316-19 A/2) R380 C421 L316 C823 TH702 C415 L319 C413 C410 C340 C404 L318 D309 C399 C397 C400 D311 R349 C402 L315 C332 R331 R346 L310 C403 C312...
  • Page 33 TM-481A PC BOARD TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION Foil side view (J79-0316-19 A/2) Ref. No. Address J701 EXT. SP IC501 IC703 IC704 IC705 IC706 D714 IC709 IC710 R831 IC713 IC714 C847 C837 Q303 Q501 IC713 Q503 Q504 Q505 C829...
  • Page 34 TM-481A PC BOARD TX-RX UNIT (X57-8130-24) (B/2): DISPLAY SECTION Component side view (J79-0316-19 B/2) VR901 HOOK J901 CALL TX-RX UNIT (X57-8130-24) (B/2): DISPLAY SECTION Foil side view (J79-0316-19 B/2) HOOK R916 R919 Q904 Q903 R917 C903 R901 R909 CN901 C910...
  • Page 35 TM-481A PC BOARD TX-RX UNIT (X57-8130-24) (B/2): DISPLAY SECTION Component side view (J79-0316-19 B/2) J79-0316-19 B/2 Ref. No. Address S901 D903 ENCODER D904 D905 D906 D907 D908 D909 D910 D911 Component side Layer 1 FUNC Layer 2 Foil side TX-RX UNIT (X57-8130-24) (B/2): DISPLAY SECTION Foil side view (J79-0316-19 B/2) Ref.

  • Page 36: Schematic Diagram

    TM-481A SCHEMATIC DIAGRAM TX-RX UNIT (X57-8130-24)(A/2) : TX-RX SECTION RX VCO Q1,2 D3,5 R:0.74V SWITCHING BUFFER AMP OSCILLATOR T:0.73V R:6.03V FREQENCY CONTROL R:6.13V R:1.03V 2SC5108(Y)F 8.2k HZU5ALL MCH3914(7)-H 2SA1832(GR)F VOLTAGE 2.7k 270n HVC359 0.5p DROPPED 2SC4738(GR)F R:6.84V T/R SWITCH PLL IC TCXO T:6.76V...
  • Page 37 TM-481A SCHEMATIC DIAGRAM TX-RX UNIT (X57-8130-24)(A/2): TX-RX SECTION D9,10 R:4.34V RF AMP RF SWITCH T:5.39V T:4.61V R:6.84V R:1.67V HSC277 R307 C308 L305 L302 2SC5108(Y)F 6.8n 4.7n R:1.81V D10 HSC277 R528 L706 L705 R:5.62V R550 R:5.34V R:2.80V 100k L71-0655-05 RF AMP R:7.50V...
  • Page 38 TM-481A SCHEMATIC DIAGRAM IC302 RA60H40471101 POWER MODULE TX-RX UNIT (X57-8130-24)(A/2): TX-RX SECTION 45W:3.59V T:7.39V 25W:3.04V DRIVE AMP D306,307 D306 ANT SWITCH Q303 C420 L407CDB C405 C413 RD00HVS1-T113 T:3.75V 1000p D307 R350 STRIP LINE C406 R381 L407CDB L319 L320 R380 L308...
  • Page 39 TM-481A SCHEMATIC DIAGRAM TX-RX UNIT (X57-8130-24)(B/2) : DISPLAY SECTION INT SP SPOUT SPGND CALL ENCODER S901 D901 W02-3704-05 REVERSE C901 Func CONNECTION PROTECTIOM 0.1u D901 R901 1SS355 R902 4.7k SEG27 7.56V SURGE SEG26 J901 ABSORPTION SEG25 R903 HOOK SEG24 4.7k...

  • Page 40: Block Diagram

    TM-481A BLOCK DIAGRAM TX-RX UNIT (X57-8130-24 B/2): Display section TX-RX UNIT (X57-8130-24 A/2): TX-RX section 2SC4649(N,P) MB15A02PFV2E1 PLLE PLL IC MCH3914 16.8MHz 2SA1832(GR)F CHARGE TCXO PUMP TCXOMOD 2SC4738(GR)F 16.8MHz MICKEY VR901 POWER R31-0662-05 PTT/TXD L77-1944-05 LOOP VARIABLE RESISTOR FILTER IC705(5/8) CONV.
  • Page 41 TM-481A BLOCK DIAGRAM D306,D307 L407CDB Q303 IC302 D9,D10 D309,D311 RD00HVS1-T113 RA60H40471101 2SC5108(Y)F 2SC5108(Y)F HSC277 JDP2S12CR TX/RX: 400.000~469.995MHz MCH3914(7)-H POWER TX/RX BUFF DRIVE COMM ANT SW MODULE TX/RX D313,D314 HSB88AS-E POWER 2SJ347F DETECTOR UMC4N 16.8MHz IC303 1st Local NJM12904RB1 TH702,TH703 Q501 449.950~519.945MHz...

  • Page 42: Level Diagram

    TM-481A LEVEL DIAGRAM Receiver Section Center Frequency 49.95MHz 450kHz W : –88.0dBm N : –85.5dBm CF501 W : –122.5dBm W : –122.0dBm W : –109.0dBm W : –110.5dBm W : –117.5dBm W : –106.5dBm /CF502 N : –122.0dBm N : –121.5dBm N : –108.5dBm...
  • Page 43 TM-481A LEVEL DIAGRAM 450kHz Audio Frequency W : –93.0dBm N : –92.0dBm CF501 /CF502 0.55Vrms 0.46Vrms 0.43Vrms 0.47Vrms 0.49Vrms 10mVrms 0.88Vrms 0.64Vrms IC501 IC709 IC709 IC709 IC709 IC705 IC715 Q706 meter. B SINAD.) To make measurements in the AF section, connect the AC level meter.

  • Page 44: Specifications

    TM-481A SPECIFICATIONS GENERAL Frequency Range TX.................. 400~470MHz RX ................. 400~470MHz Mode ................. F3E (FM) Antenna Impedance ............50 Usable Temperature Range ..........–20°C~+60°C Power Supply ..............13.8V DC±15% (11.7~15.8V) Grounding Method ............Negative ground Current Transmit (max.) ............. 14A or less Receive (at 2W output) ..........
  • Page 45 TM-481A TM-481A PC BOARD PC BOARD TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION Component side view (J79-0316-19 A/2) Component side view (J79-0316-19 A/2) Ref. No. Address IC302 IC303 IC707 IC302 IC708 IC711 6G IC712 IC715...
  • Page 46 TM-481A TM-481A PC BOARD PC BOARD TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION TX-RX UNIT (X57-8130-24) (A/2): TX-RX SECTION Foil side view (J79-0316-19 A/2) Foil side view (J79-0316-19 A/2) Ref. No. Address J701 EXT. SP IC501 R380 IC703 IC704 L316 C421...
  • Page 47 TM-481A TM-481A PC BOARD PC BOARD TX-RX UNIT (X57-8130-24) (B/2): DISPLAY SECTION TX-RX UNIT (X57-8130-24) (B/2): DISPLAY SECTION Component side view (J79-0316-19 B/2) Component side view (J79-0316-19 B/2) J79-0316-19 B/2 Ref. No. Address S901 VR901 D903 ENCODER D904 D905 D906...
  • Page 48 TX-RX UNIT (X57-8130-24)(A/2) : TX-RX SECTION TX-RX UNIT (X57-8130-24)(B/2) : DISPLAY SECTION IC302 RA60H40471101 INT SP POWER MODULE RX VCO Q1,2 D3,5 R:0.74V SWITCHING OSCILLATOR T:0.73V BUFFER AMP R:4.34V D9,10 SPOUT R:6.03V FREQENCY RF AMP T:4.61V RF SWITCH T:5.39V CONTROL R:6.13V R:1.03V 2SC5108(Y)F...
  • Page 49 TX-RX UNIT (X57-8130-24 B/2): Display section TX-RX UNIT (X57-8130-24 A/2): TX-RX section 2SC4649(N,P) MB15A02PFV2E1 PLLE D306,D307 PLL IC L407CDB Q303 IC302 D9,D10 D309,D311 RD00HVS1-T113 RA60H40471101 2SC5108(Y)F HSC277 JDP2S12CR TX/RX: 400.000~469.995MHz MCH3914(7)-H 2SC5108(Y)F 16.8MHz POWER TX/RX 2SA1832(GR)F BUFF COMM DRIVE CHARGE ANT SW MODULE TCXO...
  • Page 50 Receiver Section Center Frequency 49.95MHz 450kHz Audio Frequency W : –88.0dBm W : –93.0dBm N : –85.5dBm N : –92.0dBm W : –122.5dBm W : –122.0dBm W : –109.0dBm W : –110.5dBm W : –117.5dBm W : –106.5dBm CF501 N : –122.0dBm N : –121.5dBm N : –108.5dBm N : –109.5dBm...

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