JVC AV-21L31ME, AV-25L31ME Schematic

SERVICE MANUAL

COLOR TELEVISION

AV-21L31
AV-25L31

BASIC CHASSIS

CH

POWER

DISPLAY

MENU

CHANNEL VOLUME

CLOSED

MUTING

CAPTION

TV/VIDEO

123

456

PICTURE MODE

7809

100

RETURN

CHANNEL SCAN

OFF TIMER

ECO SENSOR

RM-C248 REMOTE CONTROL UNIT

RM-C248-2C

AV-21L31
AV-25L31

/ME

/ME

CONTENTS

a SPECIFICATIONS ....................................................................................................................................2

a OPERATING INSTRUCTIONS (APPENDIX)

a SAFETY PRECAUTIONS ......................................................................................................................... 3

a FEATURES ..............................................................................................................................................4

a FUNCTIONS .............................................................................................................................................5

a SPECIFIC SERVICE INSTRUCTIONS ....................................................................................................6

a SERVICE ADJUSTMENTS ....................................................................................................................14

a STANDARD CIRCUIT DIAGRAM (APPENDIX) .................................................................................. 2-1

a PARTS LIST ...........................................................................................................................................35

COPYRIGHT © 2002 VICTOR COMPANY OF JAPAN, LTD.

No. 51908

Mar. 2002

AV-21L31
AV-25L31

SPECIFICATIONS

Items

Dimensions (W × H × D)

Mass 22kg 30kg

TV RF System CCIR(M)

Color System TV Mode NTSC3.58, PAL-M, PAL-N

VIDEO Mode NTSC3.58, PAL-M, PAL-N

Stereo System BTSC (Multi channel Sound)

Receiving Frequency VHF (VL) 54MHz – 88MHz (02 – 06)

VHF (VH) 174MHz – 216MHz (07 – 13)

UHF 470MHz – 806MHz (14 – 69)

CATV Low Band (02 – 06, A-8) by (02 – 06 & 01)

Intermediate VIF Carrier 45.75MHz

Frequency SIF Carrier 41.25MHz (4.5MHz)

Color Sub Carrier Frequency NTSC (3.58MHz), PAL-M (3.57MHz), PAL-N (3.58MHz)

Aerial Input Terminal 75Ø Unbalanced

Power Input AC110 – 220V, 50 / 60Hz

Power Consumption 115W

Picture Tube Visible size : 51cm measured diagonally Visible side : 61cm measured

High Voltage 29kV ± 1.5kV (at cut-off in service mode) 31kV ± 1.5kV

Speaker 5 × 12cm Oval type ×2

Audio Output 5W ×2

Video / Audio Input (1 / 2 / 3) Video(1,3) : 1Vp-p, 75Ø (RCA pin jack)

59.8cm × 46.8cm × 47.2cm 68.2cm × 53.84cm × 47.8cm

High Band (07 – 13) by (07 – 13)

Mid Band (A – I) by (14 – 22)

Super Band (J – W) by (23 – 36) (54MHz – 804MHz)

Hyper Band (W+1 – W+28) by (37 – 64)

Ultra Band (W+29 – W+84) by (65 – 125)

Sub Mid Band (A8, A7 – A1) by (01, 93 –99)

TV/CATV Total Channel 181 Channel

(Max.)

Audio(1,2,3) : 500mVrms ( -4dBs ), High Impedance (RCA pin jack)

Component Input ( Input 2 )

Y : 1Vp-p positive (negative sync provided, when terminated with 75Ø)

CB/CR : 0.7Vp-p 75Ø

AV-21L31/ME

/ 75W

(Avg.) 150W(Max.) / 90W(Avg.)

Contents

AV-25L31/ME

—

—

diagonally

(at cut-off in service mode)

Video/Audio Output 1Vp-p, 75Ø (RCA pin jack)

500mVrms(-4dBs)

Low impedance (1000Hz when modulated 100%) (RCA pin jack)

Headphone Jack Stereo mini jack (3.5φ)

Remote Control Unit RM-C248-2C

(Battery size: AA/R06/UM-3 × 2)

Design & specifications are subject to change without notice.

2 No. 51908

SAFETY PRECAUTIONS

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

PLACE THIS PROBE
ON EACH EXPOSED
ME TAL PAR T

1500Ω 10W

0.15µF AC-TYPE

GOOD EARTH GROUND

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 (NEU-

TRAL) 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 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.

AV-21L31
AV-25L31

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.

(1) 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.

(2) 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 1000 ohms per volt or more sensitivity in the following manner.
Connect a 1500Ø 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.).

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 10kØ 2W resistor to the anode button.

No. 51908 3

AV-21L31
AV-25L31

FEATURES

s New chassis design enables use of an interactive on-screen control.
s Pure flat CRT produces fine textured picture in every detail.
s Wide range voltage (110V ~ 220V) for AC power input.
s With AUDIO/VIDEO/COMPONENT input terminals.
s I 2 C bus control utilizes single chip ICs.
s By means of AUTO PROGRAM, the TV stations can be selected

automatically and the TV channels can also be rearranged auto­matically.

s 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.

s Built-in OFF TIMER & RETURN +.

MAIN DIFFERENCE LIST

!

Part Name

! MAIN PWB ASS’Y SCH-1501A-M2 SCH-1502A-M2

! PICTURE TUBE A51QDX992X A59QDF891X/ST/

! DEG COIL QQW0118-001 QQW0119-001

DEF YOKE QQD0060-002 QQD0062-001

! FBT QQH0104-001 QQH0097-001

FRONT CABINET GG10129-018A-HK GG10133-013A-HK

! REAR COVER GG10130-001B-HK GG10134-001B-HK

MODEL No.

AV-21L31/ME AV-25L31/ME

4 No. 51908

FUNCTIONS

a FRONT PANEL

a REAR PANEL

COMPONENT

VIDEO-1

(

)

VIDEO-2

INPUT

INPUT

AV-21L31
AV-25L31

OUTPUT

V

Y

/

V

C

B

L

/

MONO

R

R

a REMOTE CONTROL UNIT

DISPLAY

CHANNEL VOLUME

CLOSED
CAPTION

TV/VIDEO

PICTURE MODE

CHANNEL SCAN

ECO SENSOR

V

L

L

/

MONO

RRC

RM-C248-2C

POWER

MENU

123

456

7809

RETURN

MUTING

100

OFF TIMER

RM-C248 REMOTE CONTROL UNIT

No. 51908 5

AV-21L31
AV-25L31

SPECIFIC SERVICE INSTRUCTIONS

DISASSEMBLY PROCEDURE

REMOVING THE REAR COVER

1. Unplug the power supply cord.

2. Remove the 7 screws marked
in Fig.1.

3. Withdraw the Rear cover toward you.

[CAUTION]

When reinstalling the rear cover, carefully push it inward after in-

•

serting the Main PWB into the rear cover groove.

REMOVING THE MAIN PW BOARD

After removing the rear cover.

•

1. Slightly raise the both sides of the Main PWB by hand, take off the
PB stopper marked Ç from the front cabinet.

2. Withdraw the Main PWB backward.
(If necessary, take off the wire clamp and connectors, etc.)

and 4 screws maked ı as shown

Å

REMOVING THE SPEAKER

After removing the rear cover.

•

1. Remove the 2 screws marked Î and 2 screws maked ´ as shown
in Fig.1.

2. Follow the same steps when removing the other hand speaker.

CHECKING THE MAIN PW BOARD

1. 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.

[CAUTION]

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.

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.

6 No. 51908

FRONT CABINET

PICTURE TUBE

E

(×2)

SPEAKER

MAIN PWB
(CRT SOCKET PWB)

MAIN PWB

AV-21L31
AV-25L31

D

(×2)

E

(×2)

SPEAKER

D

(×2)

REAR COVER

C

PB STOPPER

(×7)

A

(×4)

B

Fig.1

No. 51908 7

AV-21L31
AV-25L31

REMOVING THE CRT

* Replacement of the CRT should be performed by 2 or more persons.

After removing the rear cover, chassis etc.,

•

1. Putting the CRT change table on soft cloth, the CRT change table

should also be covered with such soft cloth (shown in Fig. 2).

2. While keeping the surface of CRT down, mount the TV set on the

CRT change table balanced will as shown in Fig. 3.

3. Remove 4 screws marked by arrows with a box type screwdriver as

shown in Fig. 3.
Since the cabinet will drop when screws have been removed, be sure

•

to support the cabinet with hands.

4. After 4 screws have been removed, put the cabinet slowly on cloth

(At this time, be carefully so as not to damage the front surface of the
cabinet) shown in Fig. 4.
The CRT should be assembled according to the opposite sequence

•

of its dismounting steps.

* The CRT change table should preferably be smaller that the CRT sur-

face, and its height be about 35cm.

CRT CHANGE TABLE

CLOTH

CRT
CHANGE
TABLE

Fig. 2

CRT

APPROX.
35cm

BOX
TYPE
SCREW
DRIVER

COATING OF SILICON GREASE FOR ELECTRICAL IN­SULATION ON THE CRT ANODE CAP SECTION.

Subsequent to replacement of the CRT and HV transformer or repair

•

of the anode cap, etc. by dismounting them, be sure to coat silicon
grease for electrical insulation as shown in Fig. 5.

1. Wipe around the anode button with clean and dry cloth. (Fig. 5)

2. Coat silicon grease on the section around the anode button. At this

time, take care so that any silicon greases does not sticks to the
anode button. (Fig. 6)

夝 Silicon grease product No. KS - 650N

CRT

Anode button

CABINET

Approx.
20mm (Do not
coat grease on
this section

Fig. 3

CRT

CRT
CHANGE TABLE

Fig. 4

Silicon grease
should be coated
by 5mm or more
from the outside
diameter of anode
cap.

Silicon grease

coating

Fig. 5

8 No. 51908

Anode button
(No sticking of
silicon grease)

Coating position
of silicon grease

Anode cap

Fig. 6

REPLACEMENT OF MEMORY IC

AV-21L31
AV-25L31

1. MEMORY IC

This TV uses the following memory IC.

Memory IC: IC1702 on MAIN PW Board

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”.

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
&/^ 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 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 3.) If readjustment is necessary, perform ad­justment referring to “SERVICE ADJUSTMENTS”.

SERVICE MENU

SERVICE MENU

1. IF

3. DEF

5. PRESET

7. PLUG & PLAY (OFF)

1-7 : SELECT DISPLAY : EXIT

2. VC

4. VSM PRESET

6. AUDIO

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

Fig. 1

SYSTEM CONSTANT-

SYSTEM CONSTANT SET 1

COLOR SYSTEM
COMB
TILT
SUPER BASS

>? : SEL -+ : OPE

Ι

NTSC
NO
NO
NO

DISP : EXIT

NAME OF REMOTE CONTROL KEYS

DISPLAY

DISPLAY

MENU

PICTURE
MODE

TV/VIDEO

PICTURE MODE

CHANNEL SCAN

ECO SENSOR

MENU

CHANNEL VOLUME

CLOSED
CAPTION

123

456

7809

RETURN

POWER

MUTING

100

OFF TIMER

MENU

MENU

MENU

SYSTEM CONSTANT-

SYSTEM CONSTANT SET 2

MSP
B / B SOUND
TUNER
COLOR AUTO

ΙΙ

YES
NO
MU
NO

+

>? : SEL -+ : OPE

SYSTEM CONSTANT-

SYSTEM CONSTANT SET 3

LOCK LONG WAIT

SHORT WAIT

>? : SEL -+ : OPE

No. 51908 9

DISP : EXIT

ΙΙΙ

: 001
: 001

DISP : EXIT

Fig. 2

AV-21L31
AV-25L31

SETTING OF SYSTEM CONSTANT SET

Setting item Setting content

COLOR SYSTEM

COMB

TILT

SUPER BASS

MSP

B/B SOUND

TUNER

COLOR AUTO

LOCK LONG WAIT

SHORT WAIT

NTSC TRIPLE

YES NO

YES NO

YES NO

YES NO

YES NO

MU MA

YES NO

000 255

000 255

Table 1

AV-21L31

NTSC

NO

NO

NO

YES

NO

MU

NO

001

001

Setting value

/ME

AV-25L31

/ME

10 No. 51908

USER SETTING VALUES

Setting item Setting value

SUB POWER ON

CHANNEL POSITION CH-02, AIR

CHANNEL PRESET REFER TO OPERATING INSTRUCTIONS

VOLUME 15 ± 2

TV/VIDEO TV

VNR OFF

COMPRESS (16:9) OFF

AUTO SHUTOFF OFF

CHILD LOCK OFF

BLUE BACK ON

VIDEO-2 SET VIDEO

LANGUAGE ENG

MONO SURROUND OFF

AI VOLUME ON

ON SCREEN DISPLAY POSITION INDICATION

COLOR SYSTEM NTSC

SOUND SYSTEM M

PICTURE MODE-VSM BRIGHT

OFF TIMER 00

ECO SENSOR OFF

CLOSED CAPTION OFF (CC1/T1)

AV-21L31
AV-25L31

Table 2

No. 51908 11

AV-21L31
AV-25L31

SERVICE MENU SETTING ITEMS

Service menu Setting item

1. IF 1. VCO

2. DELAY POINT

2. VC 1. CUTOFF(R/G)

2. DRIVE(R/G/B)

3. BRIGHT

4. PICTURE

5. COLOR

6. TINT

7. DETAIL

8. YDELAY

3. DEF 1. VER. SLOPE

2. VER. HEIGHT

3. VER. POSITION

4. VER. SCURVE

5. HOR. POSITION

6. HOR. WIDTH

7. EW-PIN

8. EW-TRAPEZ

9. UP CORNER

10. DW CORNER

11. HOR. PARALL

12. HOR. BOW

13. V. ZOOM

Do not adjust

Service menu Setting item

5. PRESET 1. CB

Do not adjust

6. AUDIO 1. STATUS

Do not adjust

7.

PLUG & PLAY(OFF)

Do not adjust

2. ACL

3. MUS

4. MAT

5. FCO

6. BPS

7. IFLH

8. VID

9. STM

10. AFCW

11. VSW

12. FFI

13. AGC

14. CL

15. AKB

16. HBL

17. BKS

18. READ STATUS

19. VNR

2. STANDARD SELECTION

3. FM PRESCALE

4. VSM PRESET 1. TINT

(BRIGHT/STD/SOFT) 2. COLOR

Do not adjust

3. BRIGHT

4. PICTURE

5. DETAIL

Table 3

12 No. 51908

REPLACEMENT OF CHIP COMPONENT

CAUTIONS

a

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.

SOLDERING IRON

a

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.

REPLACEMENT STEPS

a

1. How to remove Chip parts

Resistors, capacitors, etc.

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

nately melt the solder at each end.

AV-21L31
AV-25L31

2. How to install Chip parts

Resistors, capacitors, etc.

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

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

Transistors, diodes, variable resistors, etc.

(1) Apply extra solder to each lead.

SOLDER

(2) As shown in the figure, push the part with tweezers and alter-

nately melt the solder at each lead. Shift and remove the chip
part.

SOLDER

(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.

A

B

C

(4) Then solder leads B and C.

A

Note : After removing the part, remove remaining solder from the

pattern.

No. 51908 13

B

C

AV-21L31
AV-25L31

SERVICE ADJUSTMENTS

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 which set 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 adjustment-variable resistors, transformers, capacitors, etc.

7. 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

VNR OFF

BASS, TREBLE, BALANCE CENTER

TINT,COLOR,BRIGHT,PICTURE,DETAIL

CENTER

MEASURING INSTRUMENT

1. DC voltmeter (or Digital voltmeter)

2. Oscilloscope

3. Signal generator (Pattern generator) [NTSC]

4. Remote control unit

ADJUSTMENT ITEMS

B1 POWER SUPPLY

•

FOCUS ADJUSTMENT

•

IF CIRCUIT ADJUSTMENTS

•

Adjustment of VCO (CW)
Adjustment of DELAY POINT (AGC TAKE-OVER)

VC (VIDEO/CHROMA) CIRCUIT ADJUSTMENTS

•

Adjustment of WHITE BALANCE (Low light)
Adjustment of WHITE BALANCE (High light)
Adjustment of SUB BRIGHT
Adjustment of SUB CONTRAST
Adjustment of SUB COLOR-Ι
Adjustment of SUB COLOR-ΙΙ
Adjustment of SUB TINT-Ι
Adjustment of SUB TINT-ΙΙ

DEFLECTION CIRCUIT ADJUSTMENTS

•

Adjustment of V. SLOPE
Adjustment of V. POSITION
Adjustment of V. HEIGHT
Adjustment of H. POSITION

Adjustment of H. WIDTH
Adjustment of SIDE PIN
Adjustment of TRAPEZIUM
Adjustment of V. S-CURVE
Adjustment of CORNER
Adjustment of H. PARALLEL
Adjustment of H. BOW
Adjustment of V. HEIGHT
Adjustment of SIDE PIN
Adjustment of CORNER
Adjustment of H. POSITION

VSM PRESET SETTING

•

PRESET SETTING

•

AUDIO ADJUSTMENT

•

PURITY ADJUSTMENT

•

CONVERGENCE ADJUSTMENTS

•

Adjustment of STATIC CONVERGENCE
Adjustment of DYNAMIC CONVERGENCE

14 No. 51908

ADJUSTMENT LOCATIONS

AV-21L31
AV-25L31

MAIN PWB ASS'Y

POWER SW

S901

PW

DEG

IC702

S783 S781

S784 S782 S780

T

61

IC701

J773

J772 J771

J770

CN001

GND B1

5

S

41

U

S780 : MENU
S781 : CH–
S782 : CH+
S783 : VOL–
S784 : VOL+

HV

1

FRONT

16

HVT

AV IN/OUT

MAIN PWB ASS'Y

(CRT SOCKET)

(SOLDER SIDE)

J804J801 J802 J803

TU001

T

61

TP-47G

UPPER : FOCUS (F1)

LOWER : SCREEN

TOP

U

41

E1

TP-E

CRT EARTH

(BRAIDED ASS'Y)

No. 51908 15

AV-21L31
AV-25L31

BASIC OPERATION IN SERVICE MENU

1. TOOL OF SERVICE MENU OPERATION

Operate the SERVICE MENU with the remote control unit.

2. 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.VC .................................... For entering/adjusting the setting values (adjustment values)of the VIDEO/CHROMA circuit.

•

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

•

4.VSM PRESET ..................For setting the values of STANDARD,SOFT and BRIGHT.

•

5.PRESET ........................... For setting the values of the preset.

•

6.AUDIO .............................. For entering/adjusting the setting values (adjustment values)of the multiplicity sound circuit.

•

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

•

3. 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 7 on the remote control unit,and select the SUB MENU SCREEN from the SERVICE MENU.(See Fig.1 on the next
page.)

(VSM:video status memory)

SERVICE MENU → SUB MENU 1. IF

2. VC

3. DEF

4. VSM PRESET

5. PRESET

6. AUDIO

7. PLUG & PLAY (OFF)

(3) Method of Setting

*Once the setting values are set,they are memorized automatically.
*It must not adjust without inputting a signal.

1) 1. IF

[1.VCO ]

(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.

Under normal conditions, no adjustment is required.

[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. VC, 3. DEF, 4. VSM PRESET, 5. PRESET and 6. AUDIO

(a) 2 ~6 Keys.................. Select one from 2. VC, 3. DEF, 4. VSM PRESET, 5. PRESET and 6. AUDIO.

(b) MENU &/^ key ....... Select setting items.

(c) MENU –/+Key ........... Adjust the setting values of the setting items.

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

•

Use the number keys on the remote control unit for setting of WHITE BALANCE.

•

For the setting, refer to each item concerned.

3) 7. PLUG & PLAY (OFF)

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.

16 No. 51908

AV-21L31
AV-25L31

SUB MENU 1. IFSERVICE MENU

SERVICE MENU

1. IF

3. DEF

5. PRESET

7. PLUG & PLAY (OFF)

1-7 : SELECT DISPLAY : EXIT

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

2. VC

4. VSM PRESET

6. AUDIO

IF

1. VCO

2. DELAY POINT

1-2 : SELECT DISPLAY : EXIT

SUB MENU 2. VC

NTSC3.58

V/C

1. CUTOFF

60 Hz

MENU 89: SELECT

-

MENU

(R)
(G)

/+ : OPERATE

**
**

DISPLAY : EXIT

Setting item

1. CUTOFF (R/G)

2. DRIVE (R/G/B)

3. BRIGHT

4. PICTURE

5. COLOR

6. TINT

7. DETAIL

8. YDELAY

VCO (CW)

TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW

DELAY POINT VHF

AGC TAKE-OVER

-

/+ : OPERATE

MHz

*****

DISPLAY : EXIT

**

DISPLAY : EXIT

SUB MENU 6. AUDIO

1. STATUS

2. STANDARD SELECTION

3. FM PRESCALE

MENU 89: SELECT
MENU

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

STEREO
SAP
MONO

-

/+ : OPERATE

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

MHzAUDIO

*****

*****

DISPLAY : EXIT

SUB MENU 3. DEF

4 : 3 / 16 : 9

DEF

4 : 3

1. VER. SLOPE

60Hz

MENU 89: SELECT

-

/+ : OPERATE

MENU

NTSC3.58

**

DISPLAY : EXIT

1. VER. SLOPE

2. VER. HEIGHT

3. VER. POSITION

4. VER. SCURVE

5. HOR. POSITION

6. HOR. WIDTH

Setting item

7. EW-PIN

8. EW-TRAPEZ

9. UP CORNER

10. DW CORNER

11. HOR. PARALL

12. HOR. BOW

13. V. ZOOM

SUB MENU 4. VSM PRESET

BRIGHT / STD / SOFT

STANDARD

TINT
COLOR
BRIGHT
PICTURE
DETAIL

MENU 89: SELECT

-

/+ : OPERATE

MENU

**
**
**
**
**

DISPLAY : EXIT

Setting item

1. TINT

2. COLOR

3. BRIGHT

PICTURE

4.

5. DETAIL

SUB MENU 5. PRESET

Setting item

PRESET 60Hz

1. CB

MENU 89: SELECT

-

/+ : OPERATE

MENU

NTSC3.58

*

DISPLAY : EXIT

1. CB

2. ACL

3. MUS

4. MAT

5. FCO

6. BPS

7. IFLH

8. VID

9. STM

10. AFCW

11. VSW

12. FFI

13. AGC

14. CL

15. AKB

16. HBL

17. BKS

18. READ STATUS

19. VNR

Fig. 1

No. 51908 17

AV-21L31
AV-25L31

ADJUSTMENTS

B1 POWER SUPPLY

Item

Measuring

instrument

Test point Adjustment part Description

Check of
B1 POWER

Signal
Generator

SUPPLY

DC Voltmeter

FOCUS ADJUSTMENT

Item

Adjustment
of FOCUS

Measuring
instrument

Signal
generator

Remote
control unit

B1 (pin 1)
GND (pin 5)
[CN00S
connector

1. Receive a black and white signal.

2. Connect a DC voltmeter between B1 and GND
(between pins 1 and 5 of the connector CN00S).

3. Make sure that the voltage is DC135 ± 2V.

in MAIN
PWB]

Test point Adjustment part Description

FOCUS VR
[In HVT]

Notes:

• Set PICTURE MODE (VSM) to “BRIGHT”.

• The final adjustment of CONVERGENCE must be done after the
FOCUS adjustment. (CONVERGENCE is changed by FOCUS ad­justment.)
When makes difference by FOCUS adjustment, should be reconfirming
PURITY adjustment.

1. Receive a cross-hatch signal.

2. While looking at the screen center, adjust the FOCUS VR so that
the vertical and horizontal lines will be clear and in fine detail.

3. Make sure that the picture is in focus even when the screen gets
darkened.

IF CIRCUIT ADJUSTMENTS

Item

Adjustment
of VCO (CW)

Adjustment
of DELAY
POINT
(AGC
TAKE-OVER)

DELAY POINT
(AGC TAKE-OVER)

Measuring
instrument

Remote
control unit

VCO (CW)

TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW

Remote
control unit

Setting

(Adjustment time)

Test point Adjustment part Description

. MHz

DISPLAY : EXIT

VCO (CW)

fv

YELLOW

DELAY POINT

Initial setting value

17

Note:

• Under normal conditions, no adjustment is required.

1. Select 1. IF from the SERVICE MENU.

2. Select 1. VCO by pressing the 1 key on the remote control unit.

3. Receive a broadcast signal.

4. Check the characters color of the BELOW REFERENCE displayed
to yellow.

5. Press the DISPLAY key three times to return to normal screen.

1. Receive a black and white broadcast signal (color off).

2. Select 1. IF from the SERVICE MENU.

3. Select 2. DELAY POINT by pressing the 2 key on the remote con-
trol unit.

4. Adjust the MENU –/+ key in order to eliminate any noise or beat
from the image. Any increase above the initial value produces noise
and any decrease below it produces beat.

5. Press the DISPLAY key three times to return to the normal screen.

6. Turn to other channels and make sure that there are no irregulari­ties.

18 No. 51908