JVC TH-A25 Service Manual

JVC TH-A25 Service Manual

Dvd digital theater system
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SERVICE MANUAL
DVD DIGITAL THEATER SYSTEM
2003
12
MB141
SOUND
STANDBY
STANDBY/ON
1
Precaution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2
Specific Service Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
3
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
4
Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
5
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14
COPYRIGHT © 2003 VICTOR COMPANY OF JAPAN, LIMITED
TH-A25
DVD DIGIT AL CINEMA SYSTEM TH-A25

TABLE OF CONTENTS

Area suffix

J ----------------------------- U.S.A.
C -------------------------- Canada
VOLUME
SOURCE
No.MB141
2003/12

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Summary of Contents for JVC TH-A25

  • Page 1 Area suffix J ----------------------------- U.S.A. C -------------------------- Canada SOUND VOLUME DVD DIGIT AL CINEMA SYSTEM TH-A25 STANDBY STANDBY/ON SOURCE TABLE OF CONTENTS PRECAUTION............... . . 1-3 SPECIFIC SERVICE INSTRUCTIONS .
  • Page 2 SPECIFICATION Center unit (XV-THA25) Amplifier Front/Center/Rear 30 W per channel, min. RMS, driven into 6 Ω at 1 kHz, with no more than 10% total harmonic distortion 55 W, min. RMS, driven into 3 Ω at 100 Hz, with no more than 10% total harmonic distortion Subwoofer Audio Audio input sensitivity/Impedance (at 1 kHz)
  • Page 3: Precaution

    SECTION 1 PRECAUTION Safety Precautions (1) This design of this product contains special hardware and voltmeter. many circuits and components specially for safety purpos- Move the resistor connection to each exposed metal es. For continued protection, no changes should be made part, particularly any exposed metal part having a return to the original design unless authorized in writing by the path to the chassis, and measure the AC voltage across...
  • Page 4 Preventing static electricity 1.5.1 Grounding to prevent damage by static electricity Electrostatic discharge (ESD), which occurs when static electricity stored in the body, fabric, etc. is discharged, can destroy the laser diode in the traverse unit (optical pickup). Take care to prevent this when performing repairs. 1.5.2 About the earth processing for the destruction prevention by static electricity Static electricity in the work area can destroy the optical pickup (laser diode) in devices such as DVD players.
  • Page 5 Importance administering point on the safety Caution: For continued protection against risk of fire, replace only with same type T1.25A/250V for AFS1, T5A/125V for AFS2, T160mA/250V for AFS3 and T80mA/250V for AFS4. This symbol specifies type of fast operating fuse. Precaution: Pour eviter risques de feux, remplacez le fusible de surete de AFS1 comme le meme type que T1.25A/250V, et T5A/125V pour AFS2, et...
  • Page 6: Specific Service Instructions

    SECTION 2 SPECIFIC SERVICE INSTRUCTIONS This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS. 1-6 (No.MB141)
  • Page 7: Disassembly

    SECTION 3 DISASSEMBLY Main body section 3.1.1 Removing the top cover (See Figs.1 and 2) (1) From the both sides of the main body, remove the four Top cover screws A attaching the top cover. (See Fig.1) (2) From the back side of the main body, remove the four screws B attaching the top cover.
  • Page 8 3.1.2 Removing the tray door (See Figs.3 to 6) • Prior to performing the following procedures, remove the top cover. top cover • The following procedures are performed in the case of power (1) From the front side of the main body, push the disk open bottom and eject the disc tray.
  • Page 9 3.1.3 Removing the DVD mechanism assembly (See Fig.7) • Prior to performing the following procedures, remove the top cover and tray door. (1) From the top side of the main body, remove the four screws D attaching the DVD mechanism assembly. (2) Disconnect the wires from the connectors AJ1, AJS1 PCN1...
  • Page 10 3.1.7 Removing the rear panel (See Fig.11) • Prior to performing the following procedures, remove the top Rear panel Power cord cover and fan motor. (1) From the back side of the main body, remove the power cord from the rear panel in the direction of the arrow. (2) Remove the screw H, two screws K, five screws L three screws M and attaching the rear panel.
  • Page 11 3.1.10 Removing the main board (See Fig.14) • Prior to performing the following procedures, remove the top Power trans Wire clamp cover, tray door, DVD mechanism assembly, fan motor, rear panel, video board and function board. (1) From the top side of the main body, remove the nine screws P attaching the main board.
  • Page 12 Front panel assembly section 3.2.1 Removing the front board (See Fig.15) • Prior to performing the following procedures, remove the top cover, tray door and front panel assembly. Front board UCW13 Wire Power SW board (1) From the back side of the front panel assembly, remove the five screws R attaching the FRONT board.
  • Page 13: Adjustment

    SECTION 4 ADJUSTMENT This service manual does not describe ADJUSTMENT. (No.MB141)1-13...
  • Page 14: Troubleshooting

    SECTION 5 TROUBLESHOOTING MAIN 5.1.1 POWER Check for VCC(5V) Check for Input voltage Check for circuit at Sub Trans at FRONT PCB at POWER PCB ;PBD2, PT1, AFS3(Fuse) ;AIC1(7805) ;pin #17,46,72,90 of UIC1 Replace AIC1 Replace AZD1 Check normal Voltage Check resistant from GND Check for power-sense(5V)at FRONT PCB POWER PCB...
  • Page 15 5.1.2 OUTPUT Check voltage at Main PCB Check Connector PW1 ; VM, VL Check ABD2,4 Check Audio channel at CW5 Check Voltage for CW7 for input:5.1 channel Audio signal ; 12V Check circuit for AMP channel Check signal for FR/FL/C/W/RL/RR ;Out ports of FIC6, IC7, RIC5 at MAIN PCB Reference to NEXT page...
  • Page 16 5.1.3 Protection(When High Voltage at Protectiion port) 5.1.3.1 In this case "LOW" for, Base port of Q12(R2003 TR) at MAIN PCB Check voltage for IC4 Check circuit for voltage(-12V) -12V Check Voltage Check ABD 2,4 for Main AMP of Main PCB VM, VL "A"...
  • Page 17 5.1.3.2 In this case "LOW" for Base of Q13(A733) at Main PCB Check the Turn on for channel of Q35(C945) Check circuit for channel(Turn on) according feedback "A"position of previous page 5.1.3.3 Check the Connector Wire Ass'y Connectin of each PCB ;DVD MECHA - Main PCB (8P,PW3) ;POWER TRANS - Main PCB (ACW3) (No.MB141)1-17...
  • Page 18 DVD Servo parts 5.2.1 Initial operation after power ON POWER ON Tray close operation. Is Tray closed? about 3sec. Pick up head initial position. Is Tray closed? Stop Close operation. Disc present or not Wait Open Command from MPEG Laser Off Disc present Monitor Display=NO DISC CD or DVD judgement...
  • Page 19 5.2.2 Play operation Play Repeat Change Disc Motor forced accelleration seveal times Disc Type Focus Seach Is focus servo Track servo ON CLV servo ON Automatic Adjustment Automatic Adjustment is done once when the disc is replaced Read TOC Search Picture appears (No.MB141)1-19...
  • Page 20 5.2.3 PickUp Head Initial Position PickUp Head Initial Position (1) 1. Move Pick Up Head to inner direction until pin5 of MJ4="L" (2) 2. If pin5 of MJ4="L", then move Pick Up Head to outer direction for a short time. (3) 3.
  • Page 21 5.2.4 Disc Presence/Absense Judgment Disc Presence Judgment Turn On Laser Does lens move Check Is focus search with UP/DOWN peripheral voltage developed full stroke in focus at pin 11 of SIC1 circuit of DRIC1 direction? Check BUS line between SIC1 and MIC1 Check PI No signal (pin36 of RU1)
  • Page 22 5.2.5 Disc Motor Does Not Rotate Disc Motor Does Not Rotate Is Voltage of 0V developed at Check peripheral circuit of DRIC1 pin15 of SIC1 Check peripheral circuit of SIC1. Check SIC1 5.2.6 Focus Servo does not Work Focus Servo does not Work Check peripheral circuit of SIC1 and Are FE(pin42 of RIC1) and PI(pin36 of RIC1)
  • Page 23 5.2.7 Tracking Servo Does Not Work Tracking Servo Does not Work Check Voltage of Disc Judgment Error PI(pin36 of RIC1) is normal Is TE(pin41 of RIC1) Check peripheral circuit or RIC1 normal? Change PickUp or RIC1 Check peripheral circuit or RCN1 and DRIC1 Change SIC1 Check connection between PCB...
  • Page 24 5.2.8 CLV Servo Does Not Work CLV Servo Does not Work Check peripheral circuit of SIC1 Is XSRFIN(pin2 of SIC1) normal? Check peripheral circuit of DRIC1 Is RF(pin21 of RCN1) Check peripheral circuit of RIC1 normal? Check connection between PCB and MECHA 1-24 (No.MB141)
  • Page 25 DVD MPEG Parts 5.3.1 Initial operation after NO POWER ON WAIT Check Reset Voltage at 24pin of LOGO ON "NO DISC" DISPLAY Check Servo parts and MPEG (in time of absence) ATAPI Line Loading Check Servo spindle motor (in time of presence) parts Check Play...
  • Page 26 5.3.2 Logo operation Check Voltage Check 27MHZ crystal of REG2 2.85V FIg.1 REG3 3.50V Check 114MHZ(pin 102 of U13) Fig.1 Check Video signal of Video OK VQ1,VQ3,VQ4,VQ5,VQ6 5.3.3 Audio operation Check Audio Digital signal Check NEW DSP Parts at pin 33,36,37 of U13 Audio out Check Main AMP parts 1-26 (No.MB141)
  • Page 27 (No.MB141)1-27...
  • Page 28 VICTOR COMPANY OF JAPAN, LIMITED AV & MULTIMEDIA COMPANY AUDIO/VIDEO SYSTEMS CATEGORY 10-1,1chome,Ohwatari-machi,Maebashi-city,371-8543,Japan (No.MB141) Printed in Japan...
  • Page 29: Schematic Diagrams

    SCHEMATIC DIAGRAMS DVD DIGITAL THATER SYSTEM TH-A25 CD-ROM No.SML200312 Area suffix J ----------------------------- U.S.A. C -------------------------- Canada SOUND VOLUME DVD DIGITAL CINEMA S Y STEM TH-A25 STANDBY STANDBY/ON SOURCE Contents Block diagram Standard schematic diagrams 2-13 to 21 Printed circuit boards No.MB141SCH...
  • Page 30 In regard with component parts appearing on the silk-screen printed side (parts side) of the PWB diagrams, the parts that are printed over with black such as the resistor ( ), diode ( ) and ICP ( ) or identified by the " " mark nearby are critical for safety.
  • Page 31 < M E M O >...
  • Page 32: Block Diagram

    Block diagram TUNER TUNER L AUX L DVD PACK TUNER R AUX R FRONT L FRONT R REAR L CS8415 OPTICAL IN REAR R CENTER SUB WOOFER CODEC (MPEG) BA4560 (MIXER BA4560 (MIXER...
  • Page 33 M66010 LC87F67C8A EXPAND POWER 6 OHM FRONT L-CH (30 W) TDA7440 POWER 6 OHM FRONT R-CH (30 W) POWER 6 OHM REAR L-CH (30 W) RL IN RR IN C IN S/W IN POWER 6 OHM REAR R-CH (30 W) M62446AFP VOLUME/TONE POWER...
  • Page 34 Standard schematic diagrams To UW2 (SHEET 2) Main section Parts are safety assurance parts. When replacing those parts make sure to use the specified one. To UW1 (SHEET 2)
  • Page 35 To UW3 (SHEET 2) To PCN1 (SHEET 4) SHEET 1...
  • Page 36 Function section To AJS1 To VW1 (SHEET 5) (SHEET 3)
  • Page 37 To VW2 (SHEET 3) SHEET 2...
  • Page 38 Front display section...
  • Page 39 Video section SHEET 3...
  • Page 40 DVD loader section...
  • Page 41 SHEET 4 2-10...
  • Page 42 DVD MPEG DEC section 2-11...
  • Page 43 SHEET 5 2-12...
  • Page 44 Printed circuit boards Main board 2-13...
  • Page 45 2-14...
  • Page 46 Function board Forward side Reverse side 2-15...
  • Page 47 side se side 2-16...
  • Page 48 Front board Forward side (FL board) (Power SW board) Reverse side (FL board) 2-17...
  • Page 49 (Power SW board) 2-18...
  • Page 50 DVD servo control board Forward side 2-19...
  • Page 51 Reverse side 2-20...
  • Page 52 Video board 2-21...
  • Page 53 < M E M O >...
  • Page 54: Parts List

    PARTS LIST [ TH-A25 ] * All printed circuit boards and its assemblies are not available as service parts. Area suffix J ----------------------------- U.S.A. C -------------------------- Canada - Contents - 3 - 2 Exploded view of general assembly and parts list (Block No.M1) 3 - 5 Electrical parts list (Block No.01~05)
  • Page 55 Exploded view of general assmbly and parts list Block No. Tuner pack Video bo Function board DVD pack DVD board Front board...
  • Page 56 pack Video board Main board Power trans...
  • Page 57 General assembly Block No. [M][1][M][M]  Symbol No. Part No. Part Name Description Local AH64-02580A BADGE-DVD AH64-02575B WINDOW-CD AH64-02569A DOOR-CD AH61-01404A HOLDER-DOOR AH61-01325A SPRING-DOOR (x2) AH64-02574C WINDOW-FRONT AH64-02570A KNOB-VOLUME AH64-02573B DECO-VOLUME AH73-00005A RUBBER-FOOT (x4) AH63-00610A FILTER-VFD AH64-02568C CABINET-FRONT AH64-02572B KNOB-POWER AH64-02571B KNOB-FUNCTION AH61-01406A...
  • Page 58: Electrical Parts List

    Electrical parts list Main board  Symbol No. Part No. Part Name Description Local Block No. [0][1][0][0] Q25FL 0501-000010 TRANSISTOR  Symbol No. Part No. Part Name Description Local Q25FR 0501-000010 TRANSISTOR Q25RL 0501-000010 TRANSISTOR Q25RR 0501-000010 TRANSISTOR AH39-00525A LEAD CONNECTOR Q26FL 0501-000294 TRANSISTOR...
  • Page 59  Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local D33FR 0401-001090 FR DIODE C44FR 2203-000710 CHIP CAPACITOR D35FL 0401-001090 FR DIODE C44RL 2203-000710 CHIP CAPACITOR D35FR 0401-001090 FR DIODE C44RR 2203-000710 CHIP CAPACITOR D35RL 0401-001090...
  • Page 60  Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local 2007-000931 CHIP RESISTOR R79L 2007-000267 CHIP RESISTOR 2007-000766 CHIP RESISTOR R79W 2007-000267 CHIP RESISTOR 2007-000766 CHIP RESISTOR R80C 2007-001039 CHIP RESISTOR 2007-000766 CHIP RESISTOR R80F 2007-001039...
  • Page 61  Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local R75FL 2007-000941 CHIP RESISTOR AL3FL AH27-90001A COIL R76FL 2001-000429 C RESISTOR AL3FR AH27-90001A COIL R78FL 2007-001039 CHIP RESISTOR AL3RL AH27-90001A COIL R79FL 2007-000267 CHIP RESISTOR AL3RR...
  • Page 62  Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local RIC5 BA4560 1201-000163 UD10 0401-001090 FR DIODE SPK1 3716-001179 TERMINAL UD11 0401-001090 FR DIODE SPK2 3716-001205 TERMINAL UD12 0401-000101 FR DIODE UD100 0401-001090 FR DIODE UD77...
  • Page 63 Function board  Symbol No. Part No. Part Name Description Local Block No. [0][3][0][0] FC44R 2401-000588 E CAPACITOR  Symbol No. Part No. Part Name Description Local 0401-001090 FR DIODE FIC2 BA4560 1201-000163 FIC3 TDA7440D 1204-001465 2401-000407 E CAPACITOR FIC4 BA4560 1201-000163 2401-000407...
  • Page 64: Jack Board

     Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local FR63L 2007-000134 CHIP RESISTOR 3708-000266 CONNECTOR FR63R 2007-000134 CHIP RESISTOR 3708-001574 CONNECTOR FR64L 2007-000092 CHIP RESISTOR 3710-001422 CONNECTOR FR64R 2007-000092 CHIP RESISTOR 3710-001422 CONNECTOR FR65L...
  • Page 65  Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local PC13 2402-000107 E.CAPACITOR SMD 2007-000075 CHIP RESISTOR PC14 2203-005005 CHIP CAPACITOR 2007-000118 CHIP RESISTOR 2007-001042 CHIP RESISTOR 2402-000176 E.CAPACITOR SMD 2007-000084 CHIP RESISTOR 2402-000009 E CAPACITOR 2007-000113...
  • Page 66  Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local 3301-001495 BEAD-SMD DC18 2203-005005 CHIP CAPACITOR DC19 2203-005005 CHIP CAPACITOR 2203-005005 CHIP CAPACITOR 2007-000097 CHIP RESISTOR 2402-000009 E CAPACITOR 2007-000090 CHIP RESISTOR 2203-005005 CHIP CAPACITOR 2007-000134...
  • Page 67  Symbol No. Part No. Part Name Description Local  Symbol No. Part No. Part Name Description Local PL19 3301-001495 BEAD-SMD RR14 2007-000124 CHIP RESISTOR 2007-000308 CHIP RESISTOR RR15 2007-000090 CHIP RESISTOR 2203-005005 CHIP CAPACITOR RR16 2007-000090 CHIP RESISTOR 2203-005005 CHIP CAPACITOR RR18 2007-000075...
  • Page 68  Symbol No. Part No. Part Name Description Local SR34 2007-000076 CHIP RESISTOR SR35 2007-000076 CHIP RESISTOR SR36 2007-000076 CHIP RESISTOR SR37 2007-000076 CHIP RESISTOR 2011-001011 R-NET 2011-001011 R-NET 2011-000475 R-NET 2011-000585 R-NET 2011-000475 R-NET 2011-001011 R-NET 2011-001011 R-NET 2011-001011 R-NET 2011-001011 R-NET...
  • Page 69 Packing materials and accessories parts list Block No. A1,A3,A4,A5 A6,A7,A8,A9 3-16...
  • Page 70 Packing and accessories Block No. [M][3][M][M]  Symbol No. Part No. Part Name Description Local AH68-01352C INST BOOK ENG FRE A25C AH68-01352A INST BOOK A25J AH59-01226C REMOCON-ASSY AH42-00001B FM-WIRE AH42-20001P ANT LOOP ------------ BATTERY (x2) AH68-00416B IMPORTANT CARD A25C AH68-00415J IMPORTANT CARD A25J AH68-00416A...
  • Page 71 VICTOR COMPANY OF JAPAN, LIMITED AV & MULTIMEDIA COMPANY AUDIO/VIDEO SYSTEMS CATEGORY 10-1,1chome,Ohwatari-machi,Maebashi-city,371-8543,Japan Printed in Japan (No.MB141SCH)

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