JVC AV-20420, AV-20421 Service Manual Download

Page: 25 / 32

AV-20420
AV-20421

(No.52111)1-25

MTS
STEREO VCO

Signal
generator

Frequency
counter

Remote
control unit

R OUT
[AUDIO OUT]

[SOUND]
<2. FH MON>
<3. ST VCO>

(1) Receive the RF signal (no modulated sound signal)

from the antenna terminal.

(2) Select the <2. FH MON> of SOUND mode, and

change the setting value from 0 to 1.

(3) Connect the frequency counter to R OUT of the

AUDIO OUT.

(4) Select the <3. ST VCO>.
(5) Set the initial setting value of the <3. ST VCO>.
(6) Adjust the <3. ST VCO> so that the frequency

counter will display 15.73kHz

0.1kHz.

(7) Select the <2. FH MON> of the SOUND mode, and

reset the setting value from 1 to 0.

MTS SAP
VCO

Signal
generator

Frequency
counter

Remote
control unit

Resistor
[1M ohm]

MPX
Connector
4pin SDA
3pin GND

R OUT
[AUDIO OUT]

[SOUND]
<8. 5FH MON>
<9. SAP VCO>

(1) Receive the RF signal (non modulated sound signal)

from the antenna terminal.

(2) Connect the 1M ohm resistor between the pin [4] and

pin [3] of MPX connector.

(3) Select the <8. 5FH MON> of the SOUND mode, and

reset the setting value from 0 to 1.

(4) Connect the frequency counter to R out of the

AUDIO OUT.

(5) Select the <9. SAP VCO>.
(6) Set the initial setting value of <9 SAP VCO>.
(7) Adjust the <9. SAP VCO> so that the frequency

counter will display 78.67kHz

0.5kHz.

(8) Select the <8. 5FH MON> of the SOUND mode, and

reset the setting value from 1 to 0.

MTS FILTER
check

Remote
control unit

[SOUND]
<5. FILTER>

(1) Select the <5. FILTER> of the SOUND mode.
(2) Verify that the <5. FILTER> is set at its initial setting

value.

Item

Measuring

instrument

Test point

Adjustment part

Description

Setting item

2. FH MON

Initial setting value

3. ST VCO

Setting item

8. 5FH MON

Initial setting value

9. SAP VCO

Setting item

5. FILTER

Initial setting value

Summary of Contents for AV-20420, AV-20421

Page 1: ...INSTRUCTIONS 1 4 3 ADJUSTMENT 1 12 4 TROUBLE SHOOTING 1 30 POWER POWER DISPLAY DISPLAY INPUT INPUT 1 7 4 100 100 3 9 6 RETURN RETURN MUTING MUTING MENU MENU V CHIP CHIP EXIT EXIT 2 8 0 5 CH VOL VOL CH CHANNEL CHANNEL VCR CONTROL VCR CONTROL POWER POWER TV VCR TV VCR REC REC STOP STOP PAUSE PAUSE PLAY PLAY FF FF REW REW SLEEP SLEEP TIMER TIMER VIDEO VIDEO STATUS STATUS RM C205 RM C205 BASIC CHASSIS...

Page 2: ...5MHz 4 5MHz Color Sub Carrier 3 58MHz Power Input AC 120V 60Hz Power Consumption 87W Picture Tube 20 51cm measured diagonally H 40 6cm x V 30 5cm High Voltage 26 5kV 1kV at zero beam current Speaker 5 x 9cm 2 x 3 1 2 Oval type x 2 Audio Power Output 1W 1W Antenna Terminal VHF UHF F type connector 75ohm Video Audio Input 1 2 3 Video 1 3 Audio 1 2 3 S Video 1 Component 2 1V p p 75ohm RCA pin jack x ...

Page 3: ...ecked or adjusted See ADJUSTMENT OF B1 POWER SUPPLY 8 Do not check high voltage by drawing an arc Use a high voltage meter or a high voltage probe with a VTVM Discharge the picture tube before attempting meter connection by connecting a clip lead to the ground frame and connecting the other end of the lead through a 10kΩ 2W resistor to the anode button 9 When service is required observe the origin...

Page 4: ...ific channels from being selected unless the ID number is key in I2C bus control utilizes single chip IC Adoption of the VIDEO STATUS function Adoption of the ON OFF TIMER function With 75ohm V U in common F Type ANT Terminal SLEEP TIMER for setting in real time Closed caption broadcasts can be viewed Audio Video input terminal Variable Audio output terminal Built in MTS system 2 2 SYSTEM BLOCK DI...

Page 5: ...TE FRONT CABINET LC10109 016A A LC10109 017A A POWER KNOB LC30376 001A A LC30376 002A A PUSH KNOB LC30271 001A A LC30271 002A A REAR COVER LC10108 006A A LC10108 007A A POWER CORD CLAMP LC20106 001D A LC20106 002C A REMOTE CONTROL UNIT RM C205 1C RM C205W 1C WHITE MARK PACKING CASE not used GQ40012 001A A ...

Page 6: ...N PW board 1 Remove the 2 screws D 2 Then you can remove the SPEAKER 2 4 4 CHECKING THE MAIN PW BOARD 1 Pull out the MAIN CHASSIS refer to REMOVING THE MAIN PWB 2 Erect the chassis vertically so that you can easily check the MAIN PWB from the reverse solder side CAUTION When erecting the MAIN PWB be careful so that there will be no contacting with other PWB Before turning power on make sure that t...

Page 7: ...AV 20420 AV 20421 No 52111 1 7 Fig 1 FRONT CABINET CRT SOCKET PWB Within MAIN PWB BRAIDED ASSY TUNER DEG COIL HVT B C A D D SPEAKER PWB STOPPER REAR COVER MAIN PWB ...

Page 8: ...ble Please set up the value of each item correctly according to the following description 1 Press the SLEEP TIMER key and while the indication of SLEEP TIMER 0 MIN is being displayed press DISPLAY key and VIDEO STATUS key on the remote control unit simultaneously Fig 1 2 The SERVICE MENU screen of Fig 1 will be displayed 3 While the SERVICE MENU is displayed again simultaneously press the DISPLAY ...

Page 9: ...CH 02 CHANNEL PRESET See OPERATING INSTRUCTIONS VOLUME 10 INPUT TV VIDEO TV DISPLAY Off SLEEP TIMER 0 VIDEO STATUS STANDARD 2 Setting of MENU TINT Center COLOR Center PICTURE Center BRIGHT Center DETAIL Center BASS Center TREBLE Center BALANCE Center MTS STEREO TV SPEAKER ON NOISE MUTING ON SET VIDEO STATUS All center SET CLOCK Unnecessary to set ON OFF TIMER OFF LANGUAGE ENG CLOSED CAPTION OFF BA...

Page 10: ...OW LIGHT RED 7 EXT BRIGHT GREEN 8 EXT PICTURE BLUE 9 EXT DETAIL HIGH LIGHT GREEN 10 EXT BPF BLUE 11 EXT TINT RF AFC CHECK Do not adjust RF AFC 12 EXT COLOR FINE 13 V SIZE STATUS 14 V CENTER VCO CW Refer to ADJUSTMENTS PROCEDURE 15 H POSITION 16 OSD H POSITION 17 OSD V POSITION 18 H AFC 19 RF AGC 20 OSD SELECT SOUND 1 IN LEVEL 2 FH MON 3 ST VCO 4 PILOT 5 FILTER 6 LOW SEP 7 HIGH SEP 8 5FH MON 9 SAP ...

Page 11: ...ft with the tweezers and remove the chip part Transistors diodes variable resistors etc 1 Apply extra solder to each lead 2 As shown in the figure push the part with tweezers and alternately melt the solder at each lead Shift and remove the chip part Note After removing the part remove remaining solder from the pattern 2 How to install Chip parts Resistors capacitors etc 1 Apply solder to the patt...

Page 12: ...e adjustment 7 Preparation for adjustment Unless otherwise specified in the adjustment items preset the following functions with the REMOTE CONTROL UNIT 3 2 MEASURING INSTRUMENT AND FIXTURES DC voltmeter or digital voltmeter Oscilloscope Frequency counter Signal generator Pattern generator NTSC TV audio multiplex signal generator Remote control unit 3 3 ADJUSTMENT ITEMS B1 POWER SUPPLY VOLTAGE CHE...

Page 13: ...W UPPER FOCUS LOWER SCREEN U T TUNER IC201 IC702 IC701 MENU CH CH VOL VOL F901 IC921 HVT T131 3 1 CW R926 F902 TP 91 B1 TP E PW DEG AV IN OUT ON TIMER REMOCON RECEIVER S STEREO MPX TP 12B CRT SOCKET PWB MAIN PWB Within MAIN PWB ASS Y U T TP E SOLDER SIDE CRT EARTH BRAIDED ASS Y E1 TP R ...

Page 14: ... following items of settings PICTURE This mode adjusts the VIDEO CHROMA and DEFLECTION control circuit SOUND This mode adjusts the SOUND control circuit GAME This mode adjusts the detailed GAME mode settings LOW LIGHT This mode adjusts the WHITE BALANCE LOW LIGHT control circuit HIGH LIGHT This mode adjusts the WHITE BALANCE HIGH LIGHT control circuit RF AFC CHECK This is no requirement for adjust...

Page 15: ...g value will be stored automatically when release the REMOTE CONTROL UNIT keys It can adjust the items PICTURE and SOUND in the same procedure GAME LOW LIGHT AND HIGH LIGHT ADJUSTMENT MODE If select any of GAME LOW LIGHT and HIGH LIGHT items and the VOLUME key is pressed from SERVICE MENU The screens 5 6 or 7 will be displayed as shown in figure page later Since the key operation in this mode is p...

Page 16: ... BY EXIT SELECT BY OPERATE BY EXIT BY EXIT SELECT BY OPERATE BY EXIT BY EXIT BRIGHT EXIT BY EXIT BRIGHT 1 BRIGHT STATUS HIGH LIGHT TOO HIGH ABOVE REFERENCE BELOW REFERENCE TOO LOW SYNC YES RF AFC FINE STATUS 1 SERVICE MENU MAIN MENU 9 VCO CW MODE TINT COLOR PICTURE BRIGHT DETAIL ON 2 SCREEN 7 HIGH LIGHT MODE 5 GAME MODE 8 RF AFC CHK MODE DO NOT ADJUST 6 LOW LIGHT MODE 3 PICTURE MODE 4 SOUND MODE 1...

Page 17: ...n in are offset values When the four items No 7 8 11 and 12 are adjusted in the video mode the setting values in each item are revised independently 3 6 2 SOUND MODE No Setting item Variable range Initial setting value 1 BRIGHT 0 127 64 2 PICTURE 0 127 95 3 TV DTL TV DETAIL 0 63 26 4 TV BPF TV B P FILTER 0 1 0 5 TINT 0 127 70 6 COLOR 0 127 48 7 EXT BRI EXT BRIGHT 25 0 8 EXT PIC EXT PICTURE 25 0 9 ...

Page 18: ...NT 20 0 2 COLOR 20 0 3 PICTURE 20 10 4 BRIGHT 20 5 5 DETAIL 15 5 No Setting item Variable range Initial setting value 1 R CUTOFF 0 255 20 2 G CUTOFF 0 255 20 3 B CUTOFF 0 255 20 No Setting item Variable range Initial setting value 1 G DRIVE 0 255 128 2 B DRIVE 0 255 128 No Setting item Variable range Initial setting value 1 RF AFC ON OFF ON 2 FINE 77 77 Display factory setting value ...

Page 19: ...shown on the screen Then adjust CW transf until BELOW REFERENCE letters turns yellow and confirm again SYNC is YES 5 It returns the AFC to ON RF AGC Remote control unit PICTURE 19 RF AGC 1 Receive the broadcast 2 Select 19 RF AGC of the PICTURE mode 3 Press the MUTING key and turn the color off 4 Get the noise in the screen with the VOLUME key 0 side of setting value 5 Press the VOLUME key and sto...

Page 20: ...tial setting value of 13 V SIZE 4 Adjust 13 V SIZE until the vertical screen size is 92 H POSITION Signal generator Remote control unit PICTURE 15 H POS 1 Receive the crosshatch signal 2 Select the 15 H POS of the PICTURE mode 3 Set the initial setting value of the 15 H POS 4 Adjust the 15 H POS until the screen will be horizontally centered Screen size Picture size 100 92 Setting item 13 V SIZE I...

Page 21: ...by pressing the 1 key 7 Turn the SCREEN VR all the way to the left 8 Turn the SCREEN VR gradually to the right from the left until either one of the red blue or green colors appears faintly 9 Adjust the two colors which did not appear until the single horizontal line that is displayed becomes white using the 4 to 9 keys 10 Turn the SCREEN VR to where the single horizontal line glows faintly 11 Pre...

Page 22: ...em Measuring instrument Test point Adjustment part Description EXIT BY HIGH LIGHT EXIT G DRIVE B DRIVE 1 7 4 100 100 3 9 6 RETURN RETURN 2 8 5 B DRIVE EXIT G DRIVE G DRIVE B DRIVE Setting item G DRIVE Initial setting value 128 B DRIVE 128 Item Measuring instrument Test point Adjustment part Description SUB BRIGHT Remote control unit PICTURE 1 BRIGHT 1 Receive the broadcast 2 Select 1 BRIGHT of the...

Page 23: ...ast 2 Select 6 COLOR of the PICTURE mode 3 Set the initial setting value of the 6 COLOR 4 If the color is not best with the initial setting value make fine adjustment of the 6 COLOR until you get the optimum color Method of adjustment using measuring instrument 1 Receive the full field color bar signal 75 white 2 Select 6 COLOR of the PICTURE mode 3 Set the initial setting value of the 6 COLOR 4 C...

Page 24: ...strument 1 Receive the full field color bar signal 75 white 2 Select 5 TINT of the PICTURE mode 3 Set the initial setting value of the 5 TINT 4 Connect the oscilloscope between TP R and TP E 5 Adjust 5 TINT and bring the value of A in the illustration to 13V Item Measuring instrument Test point Adjustment part Description Setting item 5 TINT Initial setting value 70 V W Y C G B W 75 Y M R B 0V Ite...

Page 25: ...5FH MON 9 SAP VCO 1 Receive the RF signal non modulated sound signal from the antenna terminal 2 Connect the 1M ohm resistor between the pin 4 and pin 3 of MPX connector 3 Select the 8 5FH MON of the SOUND mode and reset the setting value from 0 to 1 4 Connect the frequency counter to R out of the AUDIO OUT 5 Select the 9 SAP VCO 6 Set the initial setting value of 9 SAP VCO 7 Adjust the 9 SAP VCO ...

Page 26: ... the 300Hz signal 3 Change the connection of the oscilloscope to R OUT of the AUDIO OUT and enlarge the voltage axis 4 Select the 6 LOW SEP of the SOUND mode 5 Set the initial setting value of the 6 LOW SEP 6 Adjust the 6 LOW SEP so that the wave element of the 300Hz signal will become minimum 7 Change the signal to 3kHz and similarly adjust the 7 HI SEP Item Measuring instrument Test point Adjust...

Page 27: ...ome into the center of the screen Fig 3 8 Move the deflection yoke forward and fix the position of the deflection yoke so that the whole screen will become green 9 Insert the wedge to the top side of the deflection yoke so that it will not move 10 Input a crosshatch signal 11 Verify that the screen is horizontal 12 Input red and blue raster signals and make sure that purity is properly adjusted Fi...

Page 28: ...and make best convergence DYNAMIC CONVERGENCE ADJUSTMENT 1 Move the deflection yoke up and down and overlap the lines in the periphery Fig 2 2 Move the deflection yoke left to right and overlap the lines in the periphery Fig 3 3 Repeat 1 and 2 above and make best convergence After adjustment fix the wedge at the original position Fasten the retainer screw of the deflection yoke Fix the 6 magnets w...

Page 29: ...OWN CIRCUIT 1 Turn the power switch to on 2 As shown in Fig 1 set the resistor between X connector 1 and 3 3 Make sure that the screen picture disappears 4 Temporarily unplug the power plug 5 Remove the resistor replaced X connector 1 and 3 6 Again plug the power plug make sure that the normal picture is displayed on the screen Fig 1 T522 CONNECTOR RESISTOR 16 7k 1 1 4W HEATER R562 D561 R561 X C56...

Page 30: ...ds intervals Check item Details of detection Method of detection State of malfunction CRT NECK protector Also detected if the power supply line output from the HVT High voltage Transformer has shorted with the ground When the vertical circuit S correction capacitor C427 is shorted detect the potential drop of the C427 and prevent the burn damage to the CRT NECK Shorting of the power supply output ...

Page 31: ...AV 20420 AV 20421 No 52111 1 31 ...

Page 32: ...Printed in Japan AV 20420 AV 20421 JVC SERVICE ENGINEERING COMPANY OF AMERICA DIVISION OF JVC AMERICAS CORP www jvcservice com US Only JVC CANADA INC Head office 21 Finchdene Square Scarborough Ontario M1X 1A7 416 293 1311 ...

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