JVC AV-21CS24, AV-21CX14 Service Manual

SERVICE MANUAL

FLAT COLOUR TELEVISION

AV-21CS24 AV-21CX14

BASIC CHASSIS

CW

TABLE OF CONTENTS

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

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

3 DISASSEMBLY ....................................................................................................................................................... 1-8

4 ADJUSTMENT ...................................................................................................................................................... 1-14

5 TROUBLESHOOTING ........................................................................................................................................... 1-30

COPYRIGHT © 2004 Victor Company of Japan, Limited

No.YA106

2004/7

SPECIFICATION

Items

Dimentions (W x H x D) 50.2cm x 47.7cm x 47.2cm

Mass 22kg

TV RF System B, G, I, D, K, M

Colour System TV Mode PAL / SECAM / NTSC3.58 / NTSC 4.43

Video Mode PAL / SECAM / NTSC3.58 / NTSC4.43

Stereo System A2(B/G) / NICAM(B/G,I,D/K) Playback

Teletext system FLOF (Fastext), WST (World Standard Text) ---

Receiving Frequency VHF Low 46.25MHz ~ 140.25MHz (AS0 ~ S6)

VHF High 147.25MHz ~ 423.25MHz (S7 ~ S36)

UHF 431.25MHz ~ 863.25MHz (S37 ~ CHINA 57)

CATV Mid: X ~ Z, S1 ~ S10

Super: S11 ~ S20

Hyper: S21 ~ S41

Intermediate VIF 38.0MHz

Frequency SIF

Colour Sub Carrier Frequency 4.43MHz (PAL), 4.40MHz / 4.25MHz (SECAM), 3.58MHz / 4.43MHz (NTSC)

Aerial Input Terminal 75Ω unbalanced, coaxial

Power Input AC110V ~ AC240V, 50Hz / 60Hz

Power Consumption 88W (Max.) / 65 W (Avg.)

Picture Tube

Screen Size Visible size: 50.5cm (Diagonal) / 40.4cm x 30.3cm (H x V)

High Voltage 32kV -1.5kV / +1.0kV (at zero beam current)

Speaker 5cm x 9cm, oval type x 2

Audio Output 3W + 3W

Video / Audio Input Video [1/2] 1V (p-p), negative sync, 75Ω, RCA pin jack x 2

(1/2) Audio [1/2] 500mV (rms) (-4dBs), High impedance, RCA pin jack x 4

Video / Audio Output Video 1V (p-p), 75Ω, RCA pin jack x 1

Headphone 3.5mm stereo mini jack x1

Remote Control Unit RM-C1281-2H



D/K: 31.5MHz (6.5MHz) D/K: 31.5MHz (6.5MHz)

[NICAM: 32.15MHz (5.85MHz)] I: 32.0MHz (6.0MHz)

I: 32.0MHz (6.0MHz) B/G: 32.5MHz (5.5MHz)

[NICAM: 31.45MHz (6.55MHz)] M: 33.5MHz (4.5MHz)

B/G: 32.5MHz (5.5MHz)

[A2: 32.26MHz (5.74MHz)]

[NICAM: 32.15MHz (5.85MHz)

M: 33.5MHz (4.5MHz)

A51LXR195X

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

Audio

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

(AA/R06/UM-3 battery x 2)

AV-21CS24 AV-21CX14

Contents

Design & specifications are subject to change without notice.

1-2 (No. YA106)

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 (

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 : (
GND, the ISOLATED (NEUTRAL) : (
EARTH : (
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 ADJUSTMENT OF B1 POWER SUPPLY).

(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 10k
2W resistor to the anode button.

) on the parts list in Service manual.

) side

) side GND and

) side GND. Don't short between the LIVE

(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.).

Alternative 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 1000 ohms per volt or
more sensitivity in the following manner. Connect a
1500

Ω 10W resistor paralleled by a 0.15µF 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 1000Ω/V,
OR MORE SENSITIVITY)

0.15µF AC-TYPE

PLACE THIS PROBE

1500Ω 10W

Ω

GOOD EARTH GROUND

ON EACH EXPOSED
ME TAL PART

(No. YA106) 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 input terminals.

2

• I

C bus control utilizes single chip ICs.

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

automatically.

• Built-in OFF TIMER & RETURN +.

2. 2 MAIN DIFFERENCE LIST

 Items AV-21CS24 AV-21CX14

 MAIN PWB ASS’Y SCW-1005A-H2 SCW-1010A-H2
 FRONT CABINET ASS’Y GG10263-002A-H GG10263-003A-H

2.3 FUNCTIONS

J

REMOTE CONTROL UNIT

RM-C1281-2H

1

2

3

4
5
6

7

8

9

10

11
12
13
14
15
16
17

18

19

20

21

22

23

24

25
26
27
28
29
30
31

SOUND SYSTEM key

1

COLOUR SYSTEM key

2

FAVORITE CHANNEL keys

3

DISPLAY BACK key

4

MENU (OK) key

5

TEXT key

6

7

SOUND TURBO key

8

PICTURE MODE key

9

SOUND setting key
(Stereo/Bilingual Ι/Bilingual ΙΙ/Monaural)

OFF TIMER key

10

RETURN + key

11

CHANNEL (-/+) keys

12

MODE key

13

INDEX key

14

15

REVEAL key

16

Not used

INPUT / STORE key

17

Not used

18

19

POWER key

TV / VIDEO key

20

21

MENU (/, /) keys

22

MUTING key

23

Number keys

-/-- key

24

25

VOLUME (-/+) keys

26

SUBPAGE key

27

HOLD key

28

CANCEL key

SIZE key

29

BASS key

30

CINEMA SURROUND key

31

1-4 (No. YA106)

J

FRONT PANEL CONTROLS

J

REAR TERMINAL

V

L / M

IN (VIDEO-2)

2

1

HEADPHONE jack

1

IN (VIDEO-2) : VIDEO

2

IN (VIDEO-2) : AUDIO L/MONO

3

IN (VIDEO-2) : AUDIO R

4

MENU (OK) button

5

CHANNEL (-/+) buttons

6

R

O

N

O

3

4

MENU

OK

5

CH

A

N

NEL

6 7

VOLUME

8

7

VOLUME (-/+) buttons

8

Remote control sensor

9

POWER lamp

10

MAIN POWER button

POWER

10

9

4 5

VIDEO-1 INPUT TERMINAL

VIDEO

1

VIDEO-1

INPUT

OUTPUT

AUDIO L/MONO

2

AUDIO R

3

OUTPUT TERMINAL

VIDEO

V

L

/

MONO

R

3

2

1

V

L

R

7

6

4

5

AUDIO L

AUDIO R

6

7

Aerial input terminal

(No. YA106) 1-5

2.3 MAIN CPU [MAIN PWB : IC701] PIN FUNCTION

Pin
No.

10 XtalIn I 24.576MHz for system clock
11 XtalOut O 24.576MHz 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 VDRB+ 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

34 L3 I Audio-L2 input (left signal)
35 R3 I Audio-R2 input (right signal)
36 L_OUT O Audio L output
37 R_OUT O Audio R output
38 DecsDem - Decoupling sound demodulator
39

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 V2 input
52 C4 I Not used
53 Audio2InL I Not used
54 Audio2InR I Not used
55 V2/Y I Video V2 input
56 L2 I Not used
57 R2 I Not used
58 Y3/Cvbs I S-Video Y1 input
59 C1 I S-Video C1 input
60 A_L O Audio L output for audio power amplifier
61 A_R O Not used
62 HP_L O Not used

Pin name I/O Function

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)

Ssif/RefIn/Avl/RefOut

QssO/AmO/AudeEm

O Automatic Volume Levelling / sound IF

input / subcarrier reference output /
external reference signal input for I signal
mixer for DVB operation

O QSS intercarrier output / AM output /

deemphasis / (front-end audio out)

Pin
No.

63 HP_R O Not used
64 CVBSO/PIP O Not used
65 SVM O Not used
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 Not used
79 G3/Y I Not used
80 B3/Pb I Not used
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 PW_LED I POWER LED control
100 V1.8C2 I 1.8V
101 VssC2 - GND
102 TIMER - Not used
103 TIMER - Not used
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 data
110 V3.3P I 3.3V

111 ROTATION O Not used
112 3.58/OTHER O NTSC 3.58 detection
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 S_V_DET 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 sub data (for memory)
128 SCL0 I I2C sub clock (for memory)

Pin name I/O Function

1-6 (No. YA106)

SECTION 3

DISASSEMBLY

3.1 DISASSEMBLY PROCEDURE

3.1.1 REMOVING THE REAR COVER

• Unplug the power cord.
(1) Remove the 5 screws [A] and 2 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 4 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. YA106) 1-7

FRONT CABINET

PICTURE TUBE

MAIN PWB
(CRT SOCKET PWB)

SPEAKER

C

(x4)

MAIN PWB

FBT

SPEAKER

C

(x4)

REAR COVER

A

(x5)

B

(x2)

1-8 (No. YA106)

Fig. 1

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 Table1.
If the value is different, select the setting item with
the MENU [
with the MENU

]/[] key, and set the correct value

[]/[] 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

SERVICE MENU

1. IF

3. AUDIO

5. VSM W/B

7. PLUG & PLAY (OFF)

1-7 : SELECT DISPLAY : EXIT

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

Fig. 1

SYSTEM CONSTANT-1

SYSTEM CONSTANT SET 1

SYSTEM
COMB
TILT
SUPER BASS
TEXT
LANGUAGE

: SEL  : OPE



SYSTEM CONSTANT-2

SYSTEM CONSTANT SET 2

SOUND
BILINGUAL
BLUE BACK MUTE
COLOUR AUTO
ECO SENSOR

: SEL  : OPE



SYSTEM CONSTANT-3

SYSTEM CONSTANT SET 3

SURROUND

: SEL  : OPE



2. V/C

4. DEF

6. S TATUS

: MULTI

DISP : EXIT

DISP : EXIT

NO
NO
NO
SINGLE
ERCMI

STEREO
NO
NO
NO
NO

YES
NOPICTURE BOOSTER
NOCOMPONENT
NOPIP
NOS INPUT

DISP : EXIT

DISPLAY / BACK

MENU

PICTURE
MODE

MENU

MENU

MENU

Fig. 2

(No. YA106) 1-9