JVC AV-21VT15 Service Manual

SERVICE MANUAL

FLAT COLOR TELEVISION

YA25420051

AV-21VT15/R

BASIC CHASSIS

1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13

5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-29

No.YA254

2005/4

SPECIFICATION

Items Contents

Dimensions (W × H × D) 64.9cm × 46.55cm × 47.35cm

Mass 25kg

TV RF System M / N

Color System TV Mode

Video Mode

Stereo System MTS (Multi-Channel Television Sound)

Receiving Frequency VHF Low

VHF High

Intermediate Frequency

Color Sub Carrier Frequency 3.58MHz (NTSC)

Aerial Input Terminal 75Ω unbalanced, coaxial

Power Input AC110V-AC240V, 50Hz / 60Hz (Operating Voltage 90V ~ 260V)

Power Consumption 121W (Max.) / 81W (Avg.)

Picture Tube A51QDX993X006

Screen Size Visible size :51.0cm (Diagonal) / 41.6cm × 31.5cm (H × V)

High Voltage 29kV ± 1.5kV (at zero beam current)

Speaker 6.5cm × 13cm, Oval type × 2

Audio Output 7W + 7W

Video / Audio Input [1/2/3]

Video / Audio Output Video

Headphone 3.5mm stereo mini jack × 1

Remote Control Unit RM-C1288-1H

S-Video [1] Mini-DIN 4 pin × 1

Video [1/2/3] 1V(p-p), negative sync, 75Ω, RCA pin jack × 3 Audio [1/2/3] 500mV(rms) (-4dBs ), high impedance, RCA pin jack × 6

Component

Video [2]

NTSC / PAL-M / PAL-N NTSC / PAL-M / PAL-N

46.25 MHz ~ 140.25 MHz (AS0 ~ S6)

147.25 MHz ~ 423.25 MHz (S7 ~ S36)

UHF

431.25 MHz ~ 863.25 MHz (S37 ~ C57)

CATV

Mid : X ~ Z, S1 ~ S10 Super: S11 ~ S20 Hyper: S21 ~ S41

VIF 38.0MHz

SIF 33.5MHz (4.5MHz)

21-inch, aspect ratio 4:3, flat square face type, tinted

Y: 1V(p-p), positive (negative sync provided), 75Ω C: 0.286V(p-p) (Burst signal), 75Ω

RCA pin jack × 3 Y:1V(p-p), positive (negative sync), 75Ω Cb/Cr:0.7V(p-p), 75Ω

1V(p-p), 75Ω, RCA pin jack × 1

Audio

500mV(rms)(-4dBs), Low impedance (400Hz when modulated 100%), RCA pin jack × 2

(AA/R06/UM-3 battery × 2)

Design & specifications are subject to change without notice.

1-2 (No.YA254)

SECTION 1

PRECAUTION

1.1 SAFETY PRECAUTIONS

(1) The design of this product contains special hardware,

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. Service should be performed by qualified personnel only.

(2) Alterations of the design or circuitry of the products should

not be made. Any design alterations or additions will void the manufacturer's warranty and will further relieve the manufacturer of responsibility for personal injury or property damage resulting therefrom.

(3) Many electrical and mechanical parts in the products have

special safety-related characteristics. These characteristics are often not evident from visual inspection nor can the protection afforded by them necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special safety characteristics are identified in the parts list of Service manual. Electrical components

having such features are identified by shading on the schematics and by ( ) on the parts list in Service manual. The use of a substitute replacement which does

not have the same safety characteristics as the recommended replacement part shown in the parts list of Service manual may cause shock, fire, or other hazards.

(4) Don't short between the LIVE side ground and

ISOLATED (NEUTRAL) side ground or EARTH side ground when repairing.

Some model's power circuit is partly different in the GND. The difference of the GND is shown by the LIVE : ( ) side GND, the ISOLATED (NEUTRAL) : ( ) side GND and EARTH : ( ) side GND. Don't short between the LIVE side GND and ISOLATED (NEUTRAL) side GND or EARTH side GND and never measure the LIVE side GND and ISOLATED (NEUTRAL) side GND or EARTH side GND at the same time with a measuring apparatus (oscilloscope etc.). If above note will not be kept, a fuse or any parts will be broken.

(5) If any repair has been made to the chassis, it is

recommended that the B1 setting should be checked or adjusted (See B1 POWER SUPPLY check).

(6) The high voltage applied to the picture tube must conform

with that specified in Service manual. Excessive high voltage can cause an increase in X-Ray emission, arcing and possible component damage, therefore operation under excessive high voltage conditions should be kept to a minimum, or should be prevented. If severe arcing occurs, remove the AC power immediately and determine the cause by visual inspection (incorrect installation, cracked or melted high voltage harness, poor soldering, etc.). To maintain the proper minimum level of soft X-Ray emission, components in the high voltage circuitry including the picture tube must be the exact replacements or alternatives approved by the manufacturer of the complete product.

(7) 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.

(8) When service is required, observe the original lead dress.

Extra precaution should be given to assure correct lead dress in the high voltage circuit area. Where a short circuit has occurred, those components that indicate evidence of overheating should be replaced. Always use the manufacturer's replacement components.

(9) Isolation Check (Safety for Electrical Shock Hazard)

After re-assembling the product, always perform an isolation check on the exposed metal parts of the cabinet (antenna terminals, video/audio input and output terminals, Control knobs, metal cabinet, screw heads, earphone jack, control shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.

a) Dielectric Strength Test

The isolation between the AC primary circuit and all metal parts exposed to the user, particularly any exposed metal part having a return path to the chassis should withstand a voltage of 3000V AC (r.m.s.) for a period of one second. (. . . . Withstand a voltage of 1100V AC (r.m.s.) to an appliance rated up to 120V, and 3000V AC (r.m.s.) to an appliance rated 200V or more, for a period of one second.) This method of test requires a test equipment not generally found in the service trade.

b) Leakage Current Check

Plug the AC line cord directly into the AC outlet (do not use a line isolation transformer during this check.). Using a "Leakage Current Tester", measure the leakage current from each exposed metal part of the cabinet, particularly any exposed metal part having a return path to the chassis, to a known good earth ground (water pipe, etc.). Any leakage current must not exceed 0.5mA AC (r.m.s.). However, in tropical area, this must not exceed 0.2mA AC (r.m.s.).

Alternate Check Method

Plug the AC line cord directly into the AC outlet (do not use a line isolation transformer during this check.). Use

an AC voltmeter having 1000Ω per volt or more sensitivity in the following manner. Connect a 1500Ω

10W resistor paralleled by a 0.15

µF AC-type capacitor

between an exposed metal part and a known good earth ground (water pipe, etc.). Measure the AC voltage across the resistor with the AC voltmeter. Move the resistor connection to each exposed metal part, particularly any exposed metal part having a return path to the chassis, and measure the AC voltage across the resistor. Now, reverse the plug in the AC outlet and repeat each measurement. Any voltage measured must not exceed 0.75V AC (r.m.s.). This corresponds to

0.5mA AC (r.m.s.). However, in tropical area, this must not exceed 0.3V AC (r.m.s.). This corresponds to 0.2mA AC (r.m.s.).

AC VOLTMETER (HAVING 1000 /V, OR MORE SENSITIVITY)

0.15 F AC-TYPE

PLACE THIS PROBE

1500 10W

GOOD EARTH GROUND

ON EACH EXPOSED ME TAL PAR T

(No.YA254)1-3

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

2.1 FEATURES

• New chassis design enables use of an interactive on-screen control.

• Pure flat CRT produces fine textured picture in every detail.

• Wide range voltage (110V ~ 240V) for AC power input.

• With AUDIO/VIDEO/S-VIDEO/COMPONENT input terminals.

C bus control utilizes single chip ICs.

•I

• By means of AUTO PROGRAM, the TV stations can be selected automatically and the TV channels can also be rearranged automatically.

• Built-in DIGITAL ECO MODE (ECONOMY, ECOLOGY). In accordance with the brightness in a room, the brightness and/or contrast of the picture can be adjusted automatically to make the optimum picture which is easy on the eye.

• Built-in OFF TIMER & RETURN +.

2.2 FUNCTIONS

 REMOTE CONTROL UNIT

RM-C1288-1H

COLOR SYSTEM key

FAVORITE CHANNEL keys

DISPLAY BACK key

MENU ( / , / ) keys

CLOSED CAPTION key

SOUND TURBO key

PICTURE MODE key

RETURN + key

OFF TIMER key

CHANNEL (-/+) keys

ECO key

POWER key

TV / VIDEO key

MENU (OK) key

MUTING key

Number keys

100+ key

VOLUME (-/+) keys

Not used

CINEMA SURROUND key

1-4 (No.YA254)

 FRONT PANEL CONTROLS

L / M

IN (VIDEO-3

POWER

)

NEL

VOLUME

 REAR TERMINAL

321 4

HEADPHONE jack

IN (VIDEO-3) : VIDEO

IN (VIDEO-3) : AUDIO L/MONO

IN (VIDEO-3) : AUDIO R

MENU (OK) button

CHANNEL (-/+) buttons

VIDEO-1

INPUT

OVER

MONO

5 6 10 118

COMPONENT

(VIDEO-2)

INPUT

MONO

OUTPUT

6 7

8 9 10 11

VOLUME (-/+) buttons

Remote control sensor

ECO sensor

POWER lamp

MAIN POWER button

VIDEO-1 INPUT TERMINAL

S-VIDEO

VIDEO

AUDIO L/MONO

AUDIO R

COMPONENT (VIDEO-2) INPUT TERMINAL

Y/VIDEO

AUDIO L/MONO

AUDIO R

OUTPUT TERMINAL

VIDEO

AUDIO L

AUDIO R

1313

Aerial input terminal

(No.YA254)1-5

2.3 MAIN CPU [MAIN PWB : IC701] PIN FUNCTION

Pin no. Pin name I/O Remark

1 VssP2 - GND

2 VssC4 - GND

3 V1.8C4 I 1.8V (Digital)

4 V3.3A3 I 3.3V

5 VrefP_Sdac I 3.3V (Positive)

6 VrefN_Sdac - GND

7 VrefP_Sdac I 3.3V (Negative)

8 VrefN_Sdac - GND

9 VrefP_Sdac I 3.3V (Positive)

10 XtalIn I 24.567MHz for system clock

11 XtalOut O 24.567MHz for system clock

12 VssA1 - GND

13 NECK I V-guard input/ I/O switch

14 CONT I 1.8V regulator control

15 V5P1 I +5V

16 Ph2 - Phase-2 filter

17 Ph1 - Phase-1 filter

18 Gnd1 - GND

19 SecPll - SECAM PLL decoupling

20 Dec8G - Bandgap decoupling

21 EW O East-West drive output

22 VDRB- O Vertical drive B output

23 VDRA+ O Vertical drive A output

24 Vif1 I Video IF input 1

25 Vif2 I Video IF input 2

26 Vsc - Vertical sawtooth capacitor

27 Iref I Reference current input

28 GndIF - GND

29 Sif1 I Sound IF input 1

30 Sif2 I Sound IF input 2

31 AGC O Tuner AGC output

32 EHT I EHT/overvoltage protection input

33 Ssif/RefIn/Avl/RefOut O

34 L3 I Audio-L3 input (left signal)

35 R3 I Audio-R3 input (right signal)

36 L_OUT O Audio L output

37 R_OUT O Audio R output

38 DecsDem - Decoupling sound demodulator

39 QssO/AmO/AudeEm O QSS intercarrier output / AM output /

40 Gnd2 - GND

41 PllIf - IF-PLL loop filter

42 SifAgc - AGC sound IF

43 IfVo/FmRo/DvbO O Not used

44 NC O Not used

45 V8AudioSwitches I 8V

46 AgcSsif - AGC capacitor second sound IF

47 V5P2 I 5V

48 V_OUT O Video output

49 L1 I Audio-L1 input

50 R1 I Audio-R1 input

51 V3 I Video V3 input

52 C4 I Not used

53 Audio2InL I Not used

54 Audio2InR I Not used

55 V2/Y I Video 2 input

56 L2 I Audio L2 input (Left signal)

57 R2 I Audio R2 input (right signal)

58 Y3/Cvbs I S-Video Y1 input

59 C1 I S-Video C1 input

60 AudioLsL O Audio L output for audio power amplifier

61 AudioLsR O Audio R output for audio power amplifier

62 HP_L O Headphone L

63 HP_R O Headphone R

Automatic Volume Levelling/ sound IF input / subcarrier reference output / external reference signal input for I signal mixer for DVB operation

deemphasis / (front-end audio out)

Pin no. Pin name I/O Remark

64 CVBSO/PIP O CVBS / PIP output

65 SVM O Scan velocity modulation output

66 FbiSo I Flyback input/sandcastle output

67 Hout O Horizontal output

68 VssComb - GND

69 V5Comb I 5V

70 Vin/R2/Pr I PIP R input

71 Uin/B2/Pb I PIP B input

72 Yin/G2/Y I PIP G input

73 Ysync I Not used

74 Yout O Not used

75 Uout/INSSW2 I YUV insertion input

76 NC O Not used

77 INSSW3 I YUV insertion input

78 R3/Pr I Component PR input (Video-2)

79 G3/Y I Component Y input (Video-2)

80 B3/Pb I Component PB input (Video-2)

81 Gnd3 - GND

82 V5P3 I 5V

83 BCL I Beam current limiter input

84 BLKIN I Black current input

85 Rout O R output

86 Gout O G output

87 Bout O B output

88 V3.3A1 I 3.3V

89 RefAdN - GND

90 V3.3RefAdP I 3.3V (Positive)

91 RefAd I 3.3/2V

92 GndA - GND

93 V1.8A I 1.8V

94 V3.3A2 I 3.3V

95 VssADC - GND

96 V1.8ADC I 1.8V

97 REMOTE I Remote control

98 PW_LED I POWER LED control

99 P11/TO I POWER LED control

100 V1.8C2 I 1.8V

101 VssC2 - GND

102 COMPONENT-PIP - Not used

103

COMB_SW_NT3.5/OTHER

104 VER_PROTECT O X-ray protect

105 S_REDUCE O Sound control

106 P00/I2SDI1 O Not used

107 POWER O SUB POWER control

108 SCL1 I I2C bus clock

109 SDA1 I/O I2C bus clock

110 V3.3P I 3.3V

111 ROTATION O ROTATION

112 3.58/OTHER O

113 A_MUTE O Audio muting

114 4.5/OTHER O NTSC 4.43 detection

115 PROT I Protect

116 ECO_IN I ECO sensor level detection

117 V1.8C1 I 1.8V (Digital)

118 DecV1V8 I 1.8V

119 KEY_IN I Key scan data

120 VDO_DET I Video DET input

121 VSSC1+P1 - Digital GND

122 P24/PWM3 I S-Video DET input

123 P25/PWM4 O GTVA_reset

124 V1.8C3 I 1.8V (Digital)

125 VssC3 - GND

126 P12/Int2 I External interrupt

127 SDA0 I/O I2C bus data (for memory)

128 SCL0 I I2C bus clock (for memory)

- Not used

NTSC 3.58 detection

1-6 (No.YA254)

SECTION 3

DISASSEMBLY

3.1 DISASSEMBLY PROCEDURE

3.1.1 REMOVING THE REAR COVER

• Unplug the power cord. (1) Remove the 9 screws [A] and 4 screws [B] as shown in

Fig.1.

(2) Withdraw the REAR COVER toward you.

CAUTION:

When reinstalling the rear cover, carefully push it inward after inserting the MAIN PWB into the REAR COVER groove.

3.1.2 REMOVING THE MAIN PW BOARD

• Remove the REAR COVER. (1) Slightly raise the both sides of the MAIN PWB by hand. (2) Withdraw the MAIN PWB backward.

(If necessary, take off the wire clamp and connectors, etc.)

3.1.3 REMOVING THE SPEAKER

• Remove the REAR COVER. (1) Remove the 2 screws [C] as shown in Fig.1. (2) Follow the same steps when removing the other hand

SPEAKER.

3.1.4 CHECKING THE MAIN PW BOARD

• To check the back side of the MAIN PWB. (1) Pull out the MAIN PWB. (Refer to REMOVING THE MAIN

PW BOARD).

(2) Erect the MAIN PWB vertically so that you can easily check

its back side.

CAUTIONS:

• Before turning on power, make sure that the CRT earth wire

and other connectors are properly connected.

• When repairing, connect the DEG. COIL to the DEG.

connector on the MAIN PWB.

• When repairing, connect the DEG. COIL to the DEG.

connector on the MAIN PWB.

3.1.5 WIRE CLAMPING AND CABLE TYING

(1) Be sure to clamp the wire. (2) Never remove the cable tie used for tying the wires

together. Should it be inadvertently removed, be sure to tie the wires with a new cable tie.

(No.YA254)1-7

FRONT CABINET

SPEAKER

PICTURE TUBE

(x2)

SPEAKER

MAIN PWB (CRT SOCKET PWB)

FBT

(x2)

MAIN PWB

1-8 (No.YA254)

REAR COVER

Fig.1

(x9)

(x4)

3.2 REPLACEMENT OF MEMORY IC

3.2.1 MEMORY IC

This TV uses the following memory IC.

Memory IC: IC702 on MAIN PWB

The memory IC memorizes data for correctly operating the video and deflection circuits. When replacing the memory IC, be sure to use the same type IC written with the initial values of data. In other words, use the specific IC listed in "PRINTED WIRING BOARD PARTS LIST". For its mounting location, refer to "ADJUSTMENT LOCATIONS".

3.2.2 PROCEDURE FOR REPLACING MEMORY IC

1. Power off

Switch the power off and unplug the power cord from the wall outlet.

2. Replacing the memory IC

Replace the memory IC with new one. Be sure to use the memory IC written with the initial data values.

3. Power on

Plug the power cord into the wall outlet and switch the power on.

4. Check and setting of SYSTEM CONSTANT SET:

(1) Press the [DISPLAY] key and the [PICTURE MODE] key

on the remote control unit simultaneously. The SERVICE MENU screen will be displayed.(See Fig.1.)

(2) In the SERVICE MENU, press the [DISPLAY] key and

[PICTURE MODE] key simultaneously. Then, the SYSTEM CONSTANT SET screen will be displayed.(See Fig.2.)

(3) Check whether the setting values of the SYSTEM

CONSTANT SET are the same as those indicated in Table 1. If the value is different, select the setting item with the MENU [] / [] key, and set the correct value with the MENU [] / [] key.

(4) Press the [DISPLAY] key twice to return to the normal

screen.

5. Receive channel setting

Refer to the OPERATING INSTRUCTIONS and set the receive channels (channels preset).

6. User setting

Check the user setting values in Table 2 and Table 3. If setting value is different, set the correct value. For setting, refer to the OPERATING INSTRUCTIONS.

7. Setting of SERVICE MENU

Verify the setting for each setting item in the SERVICE MENU.(See Table 4.) If readjustment is necessary, perform adjustment referring to "ADJUSTMENTS PROCEDURE".

NAME OF REMOTE CONTROL KEYS

SERVICE MENU

1. IF

3. AUDIO

5. VSM W/B

7. PLUG & PLAY (ON)

1-7 : SELECT DISPLAY : EXIT

******* **** ***** ***** **** **** *** ***

2. V/C

4. DEF

6. S TATUS

Fig.1

SYSTEM CONSTANT-1

SYSTEM CONSTANT

SYSTEM OTHERS COMB TILT SUPER BASS

: SEL  : OPE



SET 1

NO NO NO

DISP : EXIT

SYSTEM CONSTANT-2

SYSTEM CONSTANT SET 2

SOUND BLUE BACK MUTE ECO SENSOR

: SEL  : OPE



STEREO NO YES

DISP : EXIT

SYSTEM CONSTANT-3

SYSTEM CONSTANT SET 3

SURROUND



: SEL  : OPE

YES NOPICTURE BOOSTER YESCOMPONENT YESS INPUT

DISP : EXIT

Fig.2

DISPLAY / BACK

PICTURE MODE

(No.YA254)1-9

3.2.3 FACTORY SETTING VALUE

 SETTING OF SYSTEM CONSTANT SET

Setting item Setting content Setting value

SYSTEM OTHERS

COMB NO

TILT NO

SUPER BASS

SOUND STEREO

BLUE BACK MUTE NO

ECO SENSOR YES

SURROUND YES

PICTURE BOOSTER NO

COMPONENT YES

S INPUT YES

TAIWAN OTHERS

YES NO

STEREO PB MONO

YES NO

Table 1

1-10 (No.YA254)

 SETTING OF BASIC FUNCTIONS

Setting item Setting value

POWER Off

SUB POWER On

VOLUME 15

COLOR SYSTEM PAL-N

PICTURE MODE (VSM) BRIGHT

CINEMA SURROUND OFF

OFF TIMER OFF

CLOSED CAPTION OFF

CHANNEL POSITION CH02

Table 2

 SETTING OF MENU SCREEN

Setting item Setting value

INPUT TV

VNR AUTO

COMPRESS (16:9) OFF

AUTO SHUTOFF OFF

CHILD LOCK OFF

BLUE BACK ON

VIDEO-2 SET VIDEO

AUTO PROGRAM

CHANNEL SUMMARY

WHITE BALANCE COOL

TINT Center

COLOR Center

BRIGHT Center

PICTURE Maximum

DETAIL Center

BALANCE Center

SOUND MODE DYNAMIC

SOUND TURBO OFF

AI VOLUME ON

MTS STEREO

FAVORITE CH RED CH02

FAVORITE CH GREEN CH03

FAVORITE CH YELLOW CH04

FAVORITE CH BLUE CH05

AI ECO SENSOR OFF

AI ECO DISPLAY ON

Refer to OPERATING INSTRUCTIONS

 SERVICE MENU SETTING ITEMS

Setting item Setting value

1. IF 1. VCO

2. DELAY POINT

2. V/C 1. SCREEN

2. CUTOFF(B/G)

3. WDR(R/G/B)

4. BRIGHT(TV/VDO 1/2/3)

5. CONT(TV/VDO 1/2/3/TV 16:9/VDO 16:9)

6. COLOUR(TV/VDO1/2/3/DVD)

7. TINT(TV/VDO 1/2/3)

8. SHARP [Do not adjust]

9. Y DELAY [Do not adjust]

10. TINT DVD [Do not adjust]

11. AMP T. SHARP

3. AUDIO [Do not adjust]

4. DEF 1. V-SHIFT

5. VSM W/B (BRIGHT/STANDARD/SOFT)

(COOL/WARM/NORMAL)

6. STATUS [Display only]

7. PLUG & PLAY(ON) [Display only]

1. DCXO ADJ

2. NICAM lower ERRLIM

3. NICAM upper ERRLIM

4. A2 ID THR

5. MENU EQUALIZER

2. V-SLOPE

3. V-SIZE

4. H-CENT

5. H-SIZE

6. TRAPEZ

7. EW-PIN

8. COR-UP

9. COR-LO

10. ANGLE

11. BOW

12. V-S.CR

13. V-LIN

14. V-ZOOM

15. V-SCROLL

1. BRIGHT

2. CONT

3. COLOUR

4. SHARP

5. HUE

1. R DRIVE

2. G DRIVE

3. B DRIVE

Table 4

Table 3

(No.YA254)1-11

3.3 REPLACEMENT OF CHIP COMPONENT

3.3.1 CAUTIONS

(1) Avoid heating for more than 3 seconds. (2) Do not rub the electrodes and the resist parts of the pattern. (3) When removing a chip part, melt the solder adequately. (4) Do not reuse a chip part after removing it.

3.3.2 SOLDERING IRON

(1) Use a high insulation soldering iron with a thin pointed end of it. (2) A 30w soldering iron is recommended for easily removing parts.

3.3.3 REPLACEMENT STEPS

1. How to remove Chip parts

2. How to install Chip parts

[Resistors, capacitors, etc.]

(1) As shown in the figure, push the part with tweezers and

alternately melt the solder at each end.

(2) Shift with the tweezers and remove the chip part.

[Transistors, diodes, variable resistors, etc.]

(1) Apply extra solder to each lead.

SOLDER

[Resistors, capacitors, etc.]

(1) Apply solder to the pattern as indicated in the figure.

(2) Grasp the chip part with tweezers and place it on the

solder. Then heat and melt the solder at both ends of the chip part.

[Transistors, diodes, variable resistors, etc.]

(1) Apply solder to the pattern as indicated in the figure. (2) Grasp the chip part with tweezers and place it on the

solder.

(3) First solder lead A as indicated in the figure.

(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.

1-12 (No.YA254)

(4) Then solder leads B and C.

SECTION 4

ADJUSTMENT

4.1 ADJUSTMENT PREPARATION

(1) You can make the necessary adjustments for this unit with either the remote control unit or with the adjustment

equipment and parts as given below.

(2) Adjustment with the remote control unit is made on the basis of the initial setting values, however, the new setting

values used for setting the screen to its optimum condition may differ from the initial settings.

(3) Make sure that AC power is turned on correctly. (4) Turn on the power for the set and test equipment before use, and start the adjustment procedures after waiting at least 30

minutes. (5) Unless otherwise specified, prepare the most suitable reception or input signal for adjustment. (6) Never touch any adjustment parts, which are not specified in the list for this variable resistors, transformers, trimmer capacitors,

etc.

4.2 PRESETTING BEFORE ADJUSTMENT

Unless otherwise specified in the adjustment instructions, preset the following functions with the remote control unit.

 User mode setting position

Setting item Setting value

PICTURE MODE (VSM) BRIGHT

TINT, COLOR, BRIGHT,DETAIL Center

PICTURE Maximum

VNR OFF

AI ECO SENSOR OFF

BALANCE Center

SOUND TURBO OFF

CINEMA SURROUND OFF

COMPRESS 4:3

4.3 MEASURING INSTRUMENT AND FIXTURES

(1) DC voltmeter (or Digital voltmeter) (2) Oscilloscope (3) Signal generator (Pattern generator) [PAL/SECAM/NTSC] (4) Remote control unit

4.4 ADJUSTMENT ITEMS

 B1 VOLTAGE  FOCUS ADJUSTMENT  IF CIRCUIT ADJUSTMENTS

• IF VCO adjustment

• DELAY POINT (AGC TAKE-OVER) adjustment  VIDEO CIRCUIT ADJUSTMENTS

• WHITE BALANCE (Low light) adjustment

• WHITE BALANCE (High light) adjustment

• SUB BRIGHT adjustment

• SUB CONTRAST adjustment

• SUB COLOR 1 adjustment

• SUB COLOR 2 adjustment

• SUB TINT 1 adjustment

• SUB TINT 2 adjustment

 AUDIO SETTING

 DEFLECTION CIRCUIT ADJUSTMENTS

• V.SLOPE adjustment

• V.POSITION adjustment

• V.HEIGHT adjustment

• H.POSITION adjustment

• V.LINEARITY adjustment

• H. PARALLEL adjustment

• H.BOW adjustment

 VSM PRESET SETTING  CONVERGENCE ADJUSTMENTS

• STATIC CONVERGENCE adjustment

• DYNAMIC CONVERGENCE adjustment

(No.YA254)1-13

4.5 ADJUSTMENT LOCATIONS

POWER CORD

DEG COIL

MAIN PWB ASS'Y

POWER SW

S901

DEG

S804 S802

S805 S803 S801

IC701

J804J801 J802 J803

J808

J807

IC702

CN00C

J809

J806

CN00S

GND

FRONT

DEF

HVT

YOKE

TU001

I2C

CN00C

1. 5V

2. SCLO

3. SDAO

4. SCL1

5. SDA1

6. GND

CN00X

1. B1

2. NC

3. X-RAY2

4. X-RAY1

5. GND

MAIN PWB ASS'Y (CRT SOCKET)

(SOLDER SIDE)

TP-47R

TP-47B

TP-47R/G

TP-E

CRT EARTH

(BRAIDED ASS'Y)

UPPER : FOCUS

LOWER : SCREEN

TOP

1-14 (No.YA254)

4.6 BASIC OPERATION IN SERVICE MENU

Operate the SERVICE MENU with the remote control unit.

4.6.1 SERVICE MENU ITEMS

With the SERVICE MENU, various settings (adjustments) can be made, and they are broadly classified in the following items of settings:

1. IF For entering/adjusting the setting values (adjustment values) of the IF circuit.

2. V/C For entering/adjusting the setting values (adjustment values) of the VIDEO circuit.

3. AUDIO For entering/adjusting the setting values (adjustment values) of the AUDIO circuit.

4. DEF For entering/adjusting the setting values (adjustment values) of the DEFLECTION circuit.

5. VSM W/B For setting the values of STANDARD, SOFT, BRIGHT and COOL, NORMAL, WARM.

6. STATUS This is not used for service.

7. PLUG & PLAY (ON) This is not used for service.

4.6.2 BASIC OPERATION IN SERVICE MENU

1. HOW TO ENTER SERVICE MENU

Press the [DISPLAY] key and the [PICTURE MODE] key on the remote control unit simultaneously. The SERVICE MENU screen will be displayed. (See Fig. 1 on the next page.)

2. SELECTION OF SUB MENU SCREEN

Press one of the keys 1 to 6 on the remote control unit, and select the SUB MENU SCREEN from the SERVICE MENU. (See Fig.1 on the next page.)

SERVICE MENU → SUB MENU

1. IF 5. VSM W/B

2. V/C 6. STATUS

3. AUDIO 7. PLUG & PLAY (ON)

4. DEF

3. METHOD OF SETTING

NOTES:

• Once the setting values are set, they are memorized automatically.

• It must not be adjusted without inputting a signal.

(1) 1. IF

[1.VCO ] : Under normal conditions, no adjustment is required.

(a) [1] key Select 1. IF. (b) [1] key Select 1. VCO. (c) [DISPLAY] key When this is pressed twice, you will return to the SERVICE MENU.

[2.DELAY POINT ]

(a) [1] key Select 1. IF. (b) [2] key Select 2. DELAY POINT. (c) MENU [] / [] key Adjust the setting value. (d) [DISPLAY] key When this is pressed twice, you will return to the SERVICE MENU.

(2) 2. V/C, 3. AUDIO and 4. DEF

(a) [2] ~[4] keys Select one from 2. V/C, 3. AUDIO and 4. DEF (b) MENU [] / [] key Select setting items. (c) MENU [] / [] key Adjust the setting values of the setting items.

Use the number keys on the remote control unit for setting the WHITE BALANCE. For the setting, refer to each item concerned.

(d) [DISPLAY] key When this is pressed, you will return to the SERVICE MENU.

(3) 5. VSM W/B

(a) [5] keys Select 5. VSM W/B. (b) MENU [OK] key Select preset items. (c) MENU [] / [] key Adjust setting items. (d) MENU [] / [] key Adjust the setting values of the setting items. (e) [DISPLAY] key When this is pressed, you will return to the SERVICE MENU.

(4) 6. STATUS

This is for display only.

(5) 7. PLUG & PLAY (ON)

This is not used for service.

4. Release of SERVICE MENU

After completing the setting, return to the SERVICE MENU by pressing the [DISPLAY] key, then again press the [DISPLAY] key to return to the normal screen.

(No.YA254)1-15

+ 35 hidden pages

JVC AV-21VT15 Service Manual

AV-21VT15/R

TABLE OF CONTENTS

1.1 SAFETY PRECAUTIONS

2.1 FEATURES

2.2 FUNCTIONS

2.3 MAIN CPU [MAIN PWB : IC701] PIN FUNCTION

3.1 DISASSEMBLY PROCEDURE

3.2 REPLACEMENT OF MEMORY IC

3.3 REPLACEMENT OF CHIP COMPONENT

4.1 ADJUSTMENT PREPARATION

4.2 PRESETTING BEFORE ADJUSTMENT

4.3 MEASURING INSTRUMENT AND FIXTURES

4.4 ADJUSTMENT ITEMS

4.5 ADJUSTMENT LOCATIONS

4.6 BASIC OPERATION IN SERVICE MENU