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JVC MX-GT98V Service Manual
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JVC MX-GT98V Service Manual

JVC MX-GT98V Service Manual

Compact component system
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SERVICE MANUAL
COMPACT COMPONENT SYSTEM
MX-GT98V/MX-GT95V
MX-GT88V/MX-GT85V
MX-G78V/MX-G75V
SP-MXGT98V
SP-MXGT95V
(No MIC jack and MIC LEVEL volume for UN ver.)
Contents
Safety precautions
CA-MXGT98V
CA-MXGT95V
1-2
1-3
1-4
1-5
1-29
COPYRIGHT
2001 VICTOR COMPANY OF JAPAN, LTD.
MX-GT98V/MX-GT95V/MX-GT88V
MX-GT85V/MX-G78V/MX-G75V
Area suffix
US -------- Singapore
UN --------------Asean
COMPACT
DIGITAL AUDIO
COMPACT
SP-MXGT98V
SP-MXGT95V
DIGITAL VIDEO
until TOC read
1-33
1-34
1-34
1-35~49
No.21026
Sep. 2001

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Summary of Contents for JVC MX-GT98V

  • Page 1: Table Of Contents

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V SERVICE MANUAL COMPACT COMPONENT SYSTEM MX-GT98V/MX-GT95V MX-GT88V/MX-GT85V MX-G78V/MX-G75V Area suffix US -------- Singapore UN --------------Asean COMPACT DIGITAL AUDIO COMPACT SP-MXGT98V CA-MXGT98V SP-MXGT98V SP-MXGT95V CA-MXGT95V SP-MXGT95V DIGITAL VIDEO (No MIC jack and MIC LEVEL volume for UN ver.) Contents...
  • Page 2 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V 1. This design of this product contains special hardware and many circuits and components specially for safety purposes. For continued protection, no changes should be made to the original design unless authorized in writing by the manufacturer. Replacement parts must be identical to those used in the original circuits. Services should be performed by qualified personnel only.

  • Page 3: Important For Laser Products

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Important for laser products 5.CAUTION : If safety switches malfunction, the laser is able 1.CLASS 1 LASER PRODUCT to function. 2.DANGER : Invisible laser radiation when open and inter 6.CAUTION : Use of controls, adjustments or performance of lock failed or defeated.

  • Page 4: Preventing Static Electricity

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Preventing static electricity 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.

  • Page 5: Disassembly Method

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Disassembly method Metal cover <Main body> Removing the metal cover (See Fig.1 to 3) Remove the six screws A on the back of the body. Remove the two screws B on both sides of the body. Remove the metal cover from the body by lifting the rear part of the cover.
  • Page 6 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the CD changer mechanism CD changer mechanism assembly Front panel assembly assembly (See Fig.4 and 6) Rear panel Prior to performing the following procedure, remove the metal cover. Amplifier board CN705 Disconnect the wire from connector CN705 on the amplifier board.
  • Page 7 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Main board Wire clamp Removing the front panel assembly Amplifier board CN870 CN703 (See Fig.8 to 11) Prior to performing the following procedure, remove CN871 the metal cover and CD changer mechanism assembly. CN315 Disconnect the card wires from connector CN870, CN871 and CN315 on the main board respectively.
  • Page 8 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the tuner board (See Fig.12) Tuner board Rear panel Plastic rivet Prior to performing the following procedure, remove the metal cover. Disconnect the card wire from connector CN1 on the tuner board on the right side of the body.
  • Page 9 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Main board Removing the main board CN870 Front panel assembly (See Fig.17 and 18) CN871 CN315 Prior to performing the following procedure, remove the metal cover, the CD changer mechanism Amplifier board assembly, the rear panel and the antenna board.
  • Page 10 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the power board (See Fig.20) CN218 Power board CN219 Prior to performing the following procedure, remove the metal cover, the CD changermechanism assembly and the rear panel. CN250 Remove a wire clamp on the power board. Disconnect the wire from connector CN218, CN219 and CN250 on the power board.
  • Page 11 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Regulator board Removing the power transformer Power board CN204 assembly (See Fig.23 and 24) CN219 Prior to performing the following procedure, remove the metal cover, the CD changer mechanism assembly and the rear panel. Disconnect the wires from connector CN218 and CN219 on the power board.
  • Page 12 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V <Front panel assembly> Head amplifier & mechanismcontrol board CN306 Prior to performing the following procedure, remove the metal cover, the CD changer mechanism assembly and the front panel assembly. Removing the cassette mechanism assembly (See Fig.27) Disconnect the card wire from connector CN306 on the head amplifier &...
  • Page 13 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the preset / tuning switch Preset / tuning switch board board (See Fig.32 and 33) Prior to performing the following procedure, remove the display system control board. Pull out the preset knob on the front panel. Remove the four screws R attaching the preset / tuning switch board.
  • Page 14 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V <Speaker section> [for MX-GT98V/MX-GT95V] Removing the front panel (See Fig.1 and 2) Remove the four screws A attaching the front panel on the front of the body. Front panel Pull out the front panel toward the front and...
  • Page 15 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the speaker (squawker) (See Fig.5) Speaker (squawker) Prior to performing the following procedures, remove the front panel. Remove the four screws E attaching the speaker (squawker) on the front of the body. Disconnect the wire from the two speaker terminals of the speaker (squawker).
  • Page 16 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V [for MX-GT88V/MX-GT85V] Removing the front panel (See Fig.1) Remove the four screws A attaching the front panel on the front of the body. Pull out the front panel toward the front. Front panel Removing the supeaker (tweete) (See Fig.2) Prior to performing the following procedures, remove the front panel.
  • Page 17 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the speaker (woofer) (See Fig.4 and 5) Punch panel Prior to performing the following procedures, remove the front paenel. Remove the six screws D attaching the punch panel on the front of the body. Remove the four screws E attaching the speaker (woofer) on the front of the body.
  • Page 18 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V [for MX-G78V/MX-G75V] Removing the side cover (See Fig.1) Remove the six screws A on the side of the body. Removing the squawker speaker (See Fig.2) Side cover Prior to performing the following procedure, remove the side cover. Remove the four screws B on the side of the body.
  • Page 19 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Tweeter speaker Fig.5 Removing the woofer speaker (See Fig.6) Prior to performing the following procedure, remove the side cover and the front cover. Remove the four screws E on the front of the body. Pull out the woofer speaker toward the front and disconnect the wire (yellow and black,blue and black) from the two speaker terminals.
  • Page 20 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the CD Servo control board (See Fig.1) 1.Remove the metal cover. 2.Remove the CD changer mechanism assembly. 3.From bottom side the CD changer mechanism assembly, remove the four screws A retaining the CD servo control CN854 board.
  • Page 21 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Stopper Check whether the lifter unit stopper has been caught into the hole at the section "e" of CD tray assembly as shown in Fig.5. Make sure that the driver unit elevator is positioned as shown in Fig.6 from to the second or fifth hole on the left side face of the CD changer mechanism assembly.
  • Page 22 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Cams R1, R2 assembly Removing the CD loading mechanism assembly(See Fig.10) While turning the cams R1 and R2 assembly in the arrow direction "h" ,align the shaft "i" of the CD loading mechanism assembly to the position shown in Fig.10.
  • Page 23 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the try select switch board Chassis assembly (See Fig.14) Remove the two screws G retaining the tray select switch board. Tray select switch board Disconnect the tray select switch board from connector CN804 on the CD servo control board.
  • Page 24 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the actuator motor and belt Gear bracket (See Fig.18~21) Remove the two screws I retaining the gear bracket (See Fig.18). While pressing the pawl "t" fixing the gear bracket in the arrow direction, remove the gear bracket Pulley gear (See Fig.18).
  • Page 25 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Slit washer Removing the cams R1/R2 assembly and cam gear q(See Fig.22) Cam R2 Slit washer Remove the slit washer fixing the cams R1 and R2 assembly. Cam gear q By removing the two pawls "w" fixing the cam R1, separate R2 from R1.
  • Page 26 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V < Cassette mechanism section > Cassette mechanism Removing the playback,recording and eraser heads (See Fig.1~3) 1. While shifting the trigger arms seen on the right side of the head mount in the arrow direction,turn Flywheel R the flywheel R in counterclockwise direction until the head mount has gone out with a click (See Fig.
  • Page 27 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the head amp. and mechanism control board (See Fig. 4) 1.Remove the cassette mechanism assembly. Head amplifier & 2.After turning over the cassette mechanism mechanism control board assembly,remove the five screws "A" retaining the head amplifier & mechanism control board.
  • Page 28 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Removing the capstan motor (See Fig. 8) Capstan motor From the joint bracket, remove the two screws "C" retaining the capstan motor. Joint bracket Removing the flywheel (See Fig. 9,10) 1.Remove the head amp. and mechanism control P.C.Board.

  • Page 29: Adjustment Method

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Adjustment method Measurement instruments required for adjustment Radio input signal 1. Low frequency oscillator, AM modulation frequency : 400Hz This oscillator should have a capacity to output 0dBs Modulation factor : 30% to 600ohm at an oscillation frequency of 50Hz-20kHz.
  • Page 30 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Arrangement of adjusting positions Cassette mechanism section (Mechanism A section) Cassette mechanism section (Back side) Head azimuth Head azimuth adjusting screw adjusting screw (Reverse side) (Forward side) Head azimuth Head azimuth Playback, recording and eraser adjusting screw adjusting screw...
  • Page 31 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Tape recorder section Adjusting Items Measurement Standard Measurement method positions conditions values Confirmation Adjust the head Test tape Maximum 1.Playback the test tape VT703L. of head angle azimuth screw :VT7036L output 2.With the playback mechanism or recording &...
  • Page 32 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Electrical performance Adjusting Items Measurement Standard Measurement method positions conditions values Adjustment of AC-225 *Mode : Forward or 1.With the recording and playback mechanism, recording bias :4.20 A reverse mode load the test tapes(AC-225 to TYP ),and set the...

  • Page 33: Flow Of Functional Operation

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Flow of functional operation until TOC read Check Point Slider turns REST Play Key Power ON Confirm that the voltage at the pin5 SW ON. of CN801 is "H"\"L"\"H". Automatic tuning of TE offset Check that the voltage at the...

  • Page 34: Maintenance Of Laser Pickup

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Replacement of laser pickup Maintenance of laser pickup (1) Cleaning the pick up lens Before you replace the pick up, please try to Turn off the power switch and, disconnect the clean the lens with a alcohol soaked cotton power cord from the ac outlet.

  • Page 35: Description Of Major Ics

    MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Description of major ICs AN7345K (IC302) : PB/REC amp. 1. Block diagram NF1 OUT1 CTL1 RIN1 RNF1 ROUT1 REPPLE Source CTRL CTRL OUT2 EQ2 CTL2 RIN2 RNF2 ROUT2 2. Pin Function Symbol Function Symbol Function Power supply Playback amplifier input...
  • Page 36 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V MN101C35DEA (IC810) : System controller Pin function (1/2) Symbol Function Pin No. SVC3 Serial data output KCMND SVC3 status input input MSTAT SVC3 Serial clock input KCLK SLC/TUNER data output DATAOUT TUNER data input DATAIN SLC/TUNER clock Beat cut signal output of TUNER...
  • Page 37 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V Pin function (2/2) Symbol Function Pin No. FL grid control signal output 51~63 G13~G1 FL segment control signal output 64~87 P1~P24 SLC Chip enable signal output to IC303,IC304 SLCCE LED Control signal output (AUX) AUX LED Rolling panel motor control signal output...
  • Page 38 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V AN22000A-W (IC601) : Digital servo head amp. 1.Block diagram CBDO BDO COFTR OFTR CAGC RFIN RFOUT OFTR RF_EQ NRFDET 3TENV 3TOUT NRFDET SUBT FEOUT SUBT TEOUT TEBPF VDET VDET VREF FBAL GCTL TBAL 2. Pin function Pin No.
  • Page 39 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V BA3837 (IC466) : Mic mixer 1.Block diagram ROUT LOGIC LOUT BIAS 2.Pin function Symbol Description Pin No. Power supply Microphone mixing input MIC IN Channel L output LOUT Non connect Non connect Channel L input Signal bias BIAS...
  • Page 40 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V BU9253AS (IC902) : LPF & Echo mix. 1.Pin layout & block diagram MUTE ECHO VR BIAS ADINT IN DAINT IN ADINT OUT DAINT OUT ADLPF OUT DALPF IN ADLPF IN DALPF OUT MIX IN MIX OUT 2.Pin function Descriptions Pin No.
  • Page 41 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V LA1838 (IC1) : FM AM IF amp. & detector, FM MPX decoder 1. Block Diagram DECODER RF.AMP ANIT-BIRDIE MUTE BUFF STEREO P-DET AM IF PILOT 384KHz COMP S-METER AM/FM S-CLRVE S-METER IF-BUFF TUNING STEREO DRIVE DRIVE FM IF 2.
  • Page 42 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V LA6541-X (IC801) : Servo driver 1. Pin Layout & block diagram Vref Vin4 Vin3 Level B T L B T L Level RESET shift driver driver shift Level B T L B T L Level Regulator shift driver...
  • Page 43 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V LC72136N (IC2) : PLL frequency synthesizer 1. Pin layout FM/AM LPFOUT LPFIN CLOCK FM/ST/VCO FMIN AM/FM AMIN IFCONT SDIN IFIN 2. Block diagram Phase Reference Detector Driver Charge Pump Swallow Counter Swallow Counter 1/16,1/17 4bit 1/16,1/17 4bit Unlock...
  • Page 44 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V STK402-050[MX-GT98/95V], STK402-030[MX-GT88/85V, MX-G78/75V] (IC601) : Power amp. 1.Pin layout 2.Block diagram TR11 TR14 TR15 TR12 TR10 TR13 TR16 14 15 1-44...
  • Page 45 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V STK412-010[MX-GT98V/GT95V], STK412-000[MX-GT88V/GT85V], STK412-090[MX-G78V/G75V] (IC701) : Power amp. 1-45...
  • Page 46 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V TDA7439 (IC436) : Control volume 1.Pin layout DIG GND TREBLE(R) AGND TREBLE(L) ROUT MIN(L) LOUT MOUT(L) R-IN4 BOUT(L) R-IN3 BIN(L) R-IN2 BOUT(R) R-IN1 BIN(R) L-IN1 MOUT(R) L-IN2 MIN(R) L-IN3 L-IN4 MUXOUTR MUXOUTL TDA7439 2.Block diagram L-IN1 SPEAKER LOUT...
  • Page 47 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V BA3835S[MX-GT98/95V] (IC812) : SPI B.P.F. 1.Block Diagrams BIASC BIAS AOUT VREFC VREF REFERENCE RREF TEST CURRENT N.C. N.C. PEAK 105Hz HOLD N.C. N.C. PEAK 340Hz HOLD PEAK 1kHz DIFOUT HOLD PEAK 3.4kHz HOLD PEAK 10.5kHz HOLD 2.Pin Function...
  • Page 48 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V BU2092/F (IC811) : Port expander 1.Terminal Layout DATA CLOCK CONTROL CIRCUIT 2.Pin Function Symbol Function Pin No. DATA Serial Data input CLOCK Shift Clock of Data (Rise Edge Trigger) Latch Clock of Data (Rise Edge Trigger) 5~16 Q0~Q11...
  • Page 49 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V LB1641 (IC851, IC852) : DC motor driver 1. Pin layout GND OUT1 P1 IN2 VCC1 VCC2 P2 OUT2 2. Pin function Input Output Mode OUT1 OUT2 Brake CLOCKWISE COUNTER-CLOCKWISE Brake NJM4580L[US ver. only] (IC901) : Mic amp. 1. A OUTPUT 2.
  • Page 50 MX-GT98V/MX-GT95V/MX-GT88V MX-GT85V/MX-G78V/MX-G75V VICTOR COMPANY OF JAPAN, LIMITED AUDIO & COMMUNICATION BUSINESS DIVISION PERSONAL & MOBILE NETWORK BUSINESS UNIT. 10-1,1chome,Ohwatari-machi,Maebashi-city,371-8543,Japan 200109(V) (No.21026)

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Mx-gt95vMx-g78vMx-g75vMx-gt88vMx-gt85v