JVC AV-21L31/ME User manual

SERVICE MANUAL
AV-21L31
AV-25L31
COLOR TELEVISION
BASIC CHASSIS
CH
No. 51908
Mar. 2002
COPYRIGHT © 2002 VICTOR COMPANY OF JAPAN, LTD.
RM-C248 REMOTE CONTROL UNIT
DISPLAY
MENU
POWER
CHANNEL VOLUME
OFF TIMER
TV/VIDEO
PICTURE MODE
CHANNEL SCAN
ECO SENSOR
MUTING
RETURN
123
456
78
0
9
CLOSED
CAPTION
100
AV-21L31 /ME
AV-25L31 /ME
RM-C248-2C
CONTENTS
aSPECIFICATIONS ....................................................................................................................................2
aOPERATING INSTRUCTIONS (APPENDIX)
aSAFETY PRECAUTIONS .........................................................................................................................3
aFEATURES ..............................................................................................................................................4
aFUNCTIONS .............................................................................................................................................5
aSPECIFIC SERVICE INSTRUCTIONS ....................................................................................................6
aSERVICE ADJUSTMENTS ....................................................................................................................14
aSTANDARD CIRCUIT DIAGRAM (APPENDIX) .................................................................................. 2-1
aPARTS LIST ...........................................................................................................................................35

2 No. 51908
AV-21L31
AV-25L31
Dimensions (W ×H ×D) 59.8cm ×46.8cm ×47.2cm 68.2cm ×53.84cm ×47.8cm
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) —
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
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 75ØUnbalanced
Power Input AC110 – 220V, 50 / 60Hz
Power Consumption 115W (Max.) / 75W (Avg.) 150W(Max.) / 90W(Avg.)
Picture Tube Visible size : 51cm measured diagonally Visible side : 61cm measured
diagonally
High Voltage 29kV ± 1.5kV (at cut-off in service mode) 31kV ± 1.5kV
(at cut-off in service mode)
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)
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
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)
SPECIFICATIONS
Design & specifications are subject to change without notice.
Items Contents
AV-21L31/ME AV-25L31/ME

No. 51908 3
AV-21L31
AV-25L31
SAFETY PRECAUTIONS
1. The design of this product contains special hardware, many circuits
and components specially for safety purposes. For continued pro-
tection, 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 manufactur-
er's warranty and will further relieve the manufacturer of responsi-
bility 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 differ-
ence of the GND is shown by the LIVE : ( ) side GND, the ISO-
LATED (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 dam-
age, 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 10kØ2W 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 com-
ponents 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 hav-
ing 1000 ohms per volt or more sensitivity in the following manner.
Connect a 1500Ø10W resistor paralleled by a 0.15µF AC-type ca-
pacitor between an exposed metal part and a known good earth
ground (water pipe, etc.). Measure the AC voltage across the resis-
tor with the AC voltmeter. Move the resistor connection to each ex-
posed metal part, particularly any exposed metal part having a re-
turn 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)
PLACE THIS PROBE
ON EACH EXPOSED
METAL PART
1500Ω10W
0.15µF AC-TYPE
GOOD EARTH GROUND

4 No. 51908
AV-21L31
AV-25L31
FEATURES
sNew chassis design enables use of an interactive on-screen control.
sPure flat CRT produces fine textured picture in every detail.
sWide range voltage (110V ~ 220V) for AC power input.
sWith AUDIO/VIDEO/COMPONENT input terminals.
sI 2C bus control utilizes single chip ICs.
sBy means of AUTO PROGRAM, the TV stations can be selected
automatically and the TV channels can also be rearranged auto-
matically.
sBuilt-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.
sBuilt-in OFF TIMER & RETURN +.
MAIN DIFFERENCE LIST
!MODEL No. AV-21L31/ME AV-25L31/ME
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

No. 51908 5
AV-21L31
AV-25L31
FUNCTIONS
aREAR PANEL
aFRONT PANEL
aREMOTE CONTROL UNIT
RM-C248-2C
RM-C248 REMOTE CONTROL UNIT
DISPLAY
MENU
POWER
CHANNEL VOLUME
OFF TIMER
TV/VIDEO
PICTURE MODE
CHANNEL SCAN
ECO SENSOR
MUTING
RETURN
123
456
78
0
9
CLOSED
CAPTION
100
VIDEO-1
INPUT OUTPUT
COMPONENT
(VIDEO-2)
INPUT
V
MONO
L
/
V
Y
/
V
L
MONO
L
/
C B
RRRC
R

6 No. 51908
AV-21L31
AV-25L31
DISASSEMBLY PROCEDURE
REMOVING THE REAR COVER
1. Unplug the power supply cord.
2. Remove the 7 screws marked Åand 4 screws maked ıas shown
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 Çfrom the front cabinet.
2. Withdraw the Main PWB backward.
(If necessary, take off the wire clamp and connectors, etc.)
REMOVING THE SPEAKER
•After removing the rear cover.
1. Remove the 2 screws marked Îand 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.
SPECIFIC SERVICE INSTRUCTIONS

No. 51908 7
AV-21L31
AV-25L31
Fig.1
MAIN PWB
(CRT SOCKET PWB)
MAIN PWB
PB STOPPER
(×4)
B
(×2)
(×2)
E
(×2)
E
D
(×2)
D
C
REAR COVER
SPEAKER
A
SPEAKER
FRONT CABINET
PICTURE TUBE
(×7)

8 No. 51908
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.
COATING OF SILICON GREASE FOR ELECTRICAL IN-
SULATION 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
Fig. 2
CRT CHANGE TABLE
APPROX.
35cm
CLOTH
Fig. 3
CRT
BOX
TYPE
SCREW
DRIVER
CRT
CHANGE
TABLE
Fig. 4
CRT
CHANGE TABLE
CRT
CABINET
Fig. 5
Anode button
CRT
Silicon grease
coating
Fig. 6
Silicon grease
should be coated
by 5mm or more
from the outside
diameter of anode
cap.
Approx.
20mm (Do not
coat grease on
this section
Anode button
(No sticking of
silicon grease)
Anode cap
Coating position
of silicon grease

No. 51908 9
AV-21L31
AV-25L31
REPLACEMENT OF MEMORY IC
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 PIC-
TURE MODE key simultaneously. Then, the SYSTEM CON-
STANT 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 ad-
justment referring to “SERVICE ADJUSTMENTS”.
NAME OF REMOTE CONTROL KEYS
1. IF
3. DEF
5. PRESET
7. PLUG & PLAY (OFF)
2. VC
6. AUDIO
4. VSM PRESET
SERVICE MENU
SERVICE MENU
1-7 : SELECT DISPLAY : EXIT
******* **** ***** *****
**** **** *** ***
Fig. 1
Fig. 2
DISPLAY
MENU
POWER
CHANNEL VOLUME
OFF TIMER
TV/VIDEO
PICTURE MODE
CHANNEL SCAN
ECO SENSOR
MUTING
RETURN
123
456
78
0
9
CLOSED
CAPTION
100
MENU
MENU
MENU +
DISPLAY
MENU
PICTURE
MODE
SYSTEM CONSTANT- Ι
>? : SEL - + : OPE
COMB
TILT
NTSC
NO
NO
SUPER BASS NO
SYSTEM CONSTANT SET 1
COLOR SYSTEM
DISP : EXIT
SYSTEM CONSTANT- ΙΙ
>? : SEL - + : OPE
B / B SOUND
YES
NO
TUNER MU
COLOR AUTO NO
SYSTEM CONSTANT SET 2
MSP
DISP : EXIT
SYSTEM CONSTANT- ΙΙΙ
>? : SEL - + : OPE
SHORT WAIT
: 001
: 001
SYSTEM CONSTANT SET 3
LOCK LONG WAIT
DISP : EXIT

10 No. 51908
AV-21L31
AV-25L31
Setting item Setting content
Setting value
YES NO
NTSC TRIPLE
YES NO
YES NO
YES NO
YES NO
MU MA
YES NO
000 255
000 255
AV-25L31 /ME AV-21L31 /ME
COLOR SYSTEM
COMB
TILT
SUPER BASS
MSP
B/B SOUND
TUNER
COLOR AUTO
LOCK LONG WAIT
SHORT WAIT
YES
NO
NO
NO
NTSC
NO
MU
NO
001
001
SETTING OF SYSTEM CONSTANT SET
Table 1

No. 51908 11
AV-21L31
AV-25L31
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)
USER SETTING VALUES
Table 2

12 No. 51908
AV-21L31
AV-25L31
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
4. VSM PRESET 1. TINT
(BRIGHT/STD/SOFT) 2. COLOR
3. BRIGHT
4. PICTURE
5. DETAIL
Service menu Setting item
SERVICE MENU SETTING ITEMS
Service menu Setting item
5. PRESET 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
6. AUDIO 1. STATUS
2. STANDARD SELECTION
3. FM PRESCALE
7. PLUG & PLAY(OFF)
Do not adjust
Do not adjust
Do not adjust
Do not adjust
Do not adjust
Table 3

No. 51908 13
AV-21L31
AV-25L31
aCAUTIONS
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.
aSOLDERING 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.
aREPLACEMENT STEPS
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.
(2) Shift with 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 alter-
nately melt the solder at each lead. Shift and remove the chip
part.
Note : After removing the part, remove remaining solder from the
pattern.
REPLACEMENT OF CHIP COMPONENT
2. How to install Chip parts
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 Aas indicated in the figure.
(4) Then solder leads Band C.
SOLDER SOLDER
A
B
C
A
B
C

14 No. 51908
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.
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
•User mode setting 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

No. 51908 15
AV-21L31
AV-25L31
ADJUSTMENT LOCATIONS
E1
TOP
CRT EARTH
(SOLDER SIDE)
(BRAIDED ASS'Y)
U
TP-47G
HV
41
GND B1
UPPER : FOCUS (F1)
IC702
MAIN PWB ASS'Y
(CRT SOCKET)
T
61
41
FRONT
AV IN/OUT
HVT
MAIN PWB ASS'Y
1
61
16
5
S
U
LOWER : SCREEN
TU001
J770
S901
J773
S784 S782 S780
S783 S781 J772 J771
J804J801 J802 J803
IC701
CN001
T
PW
DEG
TP-E
S780 : MENU
S781 : CH–
S782 : CH+
S783 : VOL–
S784 : VOL+
POWER SW

16 No. 51908
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.
(VSM:video status memory)
•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.)
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.
•Use the number keys on the remote control unit for setting of 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) 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.

No. 51908 17
AV-21L31
AV-25L31
Fig. 1
1-2 : SELECT DISPLAY : EXIT
SUB MENU 1. IFSERVICE MENU
1. IF
3. DEF
5. PRESET
7. PLUG & PLAY (OFF)
2. VC
6. AUDIO
4. VSM PRESET
SERVICE MENU
1-7 : SELECT DISPLAY : EXIT
******* **** ***** *****
**** **** *** ***
1. VCO
2. DELAY POINT
IF VCO (CW)
*****
MHz
DISPLAY : EXIT
TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW
DELAY POINT VHF
AGC TAKE-OVER
**
- /+: OPERATE DISPLAY : EXIT
SUB MENU 2. VC
60 Hz
Setting item
1. CUTOFF (R/G)
2. DRIVE (R/G/B)
3. BRIGHT
4. PICTURE
5. COLOR
6. TINT
7. DETAIL
8. YDELAY
4 : 3 / 16 : 9
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 6. AUDIO
1. STATUS ******* *********
2. STANDARD SELECTION
*****
3. FM PRESCALE
STEREO
** ***
SAP
** ***
MONO
** ***
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
SUB MENU 3. DEF
60Hz
NTSC3.58
1. CUTOFF (R)
(G)
**
**
V/C
NTSC3.58
1. VER. SLOPE
**
DEF
*****
MHzAUDIO
4 : 3
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
SUB MENU 5. PRESET
NTSC3.58
1. CB
*
PRESET 60Hz
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
SUB MENU 4. VSM PRESET
TINT
**
COLOR
**
BRIGHT
**
PICTURE
**
DETAIL
**
STANDARD
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
1. CB
2. ACL
3. MUS
4. MAT
5. FCO
6. BPS
7. IFLH
8. VID
9. STM
Setting item
10. AFCW
11. VSW
12. FFI
13. AGC
14. CL
15. AKB
16. HBL
17. BKS
18. READ STATUS
19. VNR
BRIGHT / STD / SOFT
1. TINT
2. COLOR
3. BRIGHT
4. PICTURE
5. DETAIL
Setting item

18 No. 51908
AV-21L31
AV-25L31
ADJUSTMENTS
Item Measuring
instrument Test point Adjustment part Description
Check of
B1 POWER
SUPPLY
Signal
Generator
DC Voltmeter
B1 (pin 1)
GND (pin 5)
[CN00S
connector
in MAIN
PWB]
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.
Adjustment
of FOCUS
FOCUS VR
[In HVT]
Item Measuring
instrument Test point Adjustment part Description
FOCUS ADJUSTMENT
B1 POWER SUPPLY
Signal
generator
Remote
control unit
Notes:
• Set PICTURE MODE (VSM) to “BRIGHT”.
• The final adjustment of CONVERGENCE must be done after the
FOCUS adjustment. (CONVERGENCE is changed by FOCUS ad-
justment.)
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.
Adjustment
of VCO (CW)
VCO (CW)
Item Measuring
instrument Test point Adjustment part Description
IF CIRCUIT ADJUSTMENTS
Remote
control unit
Note:
• Under normal conditions, no adjustment is required.
1. Select 1. IF from the SERVICE MENU.
2. Select 1. VCO by pressing the 1key 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.
TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW
VCO (CW) . MHz
DISPLAY : EXIT
fv
YELLOW
Adjustment
of DELAY
POINT
(AGC
TAKE-OVER)
DELAY POINT
Remote
control unit
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 2key 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 irregulari-
ties.
Setting Initial setting value
(Adjustment time)
DELAY POINT 17
(AGC TAKE-OVER)

No. 51908 19
AV-21L31
AV-25L31
VC (VIDEO/CHROMA) CIRCUIT ADJUSTMENTS
The setting (adjustment) using the remote control unit is made on the basis of the initial setting values.
The setting values which adjust the screen to the optimum condition can be different from the initial setting values.
•Do not change the initial setting values of the setting (adjustment) items not listed in “ADJUSTMENT”.
[SUB MENU 2. VC] : Do not adjust.
Setting (Adjustment)
Variable ran
Initial setting value
item NTSC3.58 COMPONENT Remark
Item Measuring
instrument Test point Adjustment part Description
Adjustment
of WHITE
BALANCE
(Low light)
1. CUTOFF (R)
CUTOFF (G)
SCREEN VR
[In HVT]
Note:
• Set PICTURE MODE (VSM) to “BRIGHT”.
1. Receive a NTSC black and white signal (color off).
2. Select 2. VC from the SERVICE MENU.
3. Select 1. CUTOFF (R) and (G) with MENU &/^key, and set each
value to initial setting value with the 4and 7keys, or 5and 8 keys on
the remote control unit.
4. Press the 1key on the remote control unit to produce a single hori-
zontal line.
5. Turn the SCREEN VR fully counterclockwise, then slowly turn it clock-
wise to where a red, blue or green color is faintly visible.
6. Use the keys 4and 7or 5and 8 on the remote control unit and
adjust the other 2 colors to where the single horizontal line appears
white.
7. Turn the SCREEN VR to where the single horizontal line glows faintly.
8. Press the 2key to return to 1. CUTOFF screen.
9. Press the DISPLAY key twice to return to the normal screen.
Setting (Adjustment) Variable Initial setting
Item range value
1. CUT OFF R –7 — +8 0
G –7 — +8 0
NTSC3.58
1. CUTOFF
60 Hz
(R)
(G)
**
**
V/C
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
Signal
generator
Remote
control unit
G. CUTOFF ( 8 )
H.LINE OFF
H.LINE ON
12 3
4
789
56
R. CUTOFF (
8 )
R. CUTOFF (
9
)
G.CUTOFF (
9
)
REMOTE CONTROL UNIT
1 CUT-OFF (R/G) -7 –+8 0
2 DRIVE (R/G/B) -30 –+31 0
3 BRIGHT (COM./TV/V-1/V-2/V-3) -30 –+31 0/-18/0/0/0
4 PICTURE -30 –+31 -20 —
5 COLOR -30 –+31 -12 +10
6 TINT (TV/VIDEO) -30 –+31 -15/0 —
7 DETAIL (TV/VIDEO) -30 –+31 -16/-2 —/0
8 Y DELAY (TV/VIDEO) -8 –+7 0/+1 —

20 No. 51908
AV-21L31
AV-25L31
Item Measuring
instrument Test point Adjustment part Description
Adjustment
of
SUB BRIGHT
Remote
control unit
Notes:
•Proceed to the following adjustment after having completed the ad-
justments of LOW LIGHT WHITE BALANCE and HIGH LIGHT WHITE
BALANCE.
•Set PICTURE MODE (VSM) to “BRIGHT”.
1. Receive a broadcast.
2. Select 2. VC from the SERVICE MENU.
3. Select 3. BRIGHT with the MENU &/^key.
4. Set the initial setting value with the MENU –/+ key.
5. If the brightness is not best with the initial setting value, make fine
adjustment until you get the best brightness.
6. Press the DISPLAY key twice to return to the normal screen.
3. BRIGHT
Adjustment
of
SUB
CONTRAST
Remote
control unit
Notes:
•Proceed to the following adjustment after having completed the ad-
justment of SUB BRIGHT.
•Set PICTURE MODE (VSM) to “BRIGHT”.
1. Receive a broadcast.
2. Select 2. VC from the SERVICE MENU.
3. Select 4. PICTURE with the MENU &/^key.
4. Set the initial setting value with the MENU –/+ key.
5. If the contrast is not best with the initial setting value, make fine
adjustment until you get the best contrast.
6. Press the DISPLAY key twice to return to the normal screen.
4. PICTURE
Adjustment
of WHITE
BALANCE
(High light)
Signal
generator
Remote
control
unit
2. DRIVE (R)
DRIVE (G)
DRIVE (B)
Notes:
•Proceed to the following adjustment after having completed the ad-
justment of LOW LIGHT WHITE BALANCE.
•Set PICTURE MODE (VSM) to “BRIGHT”.
1. Receive a NTSC black and white signal (color off).
2. Select 2. VC from the SERVICE MENU.
3. Select 2. DRIVE (R), (G) and (B) with MENU &/^key, and set
each value to initial setting value with the 4to 9keys on the remote
control unit.
4. Use the keys 4to 9to produce a white screen.
5. Press the DISPLAY key twice to return to the normal screen.
Setting (Adjustment) Variable Initial setting
Item range value
R–30 —+31 0
2. DRIVE G –30 —+31 0
B–30 —+31 0
G. DRIVE ( 8 )
12 3
4
789
56
R. DRIVE (
8 ) B. DRIVE ( 8 )
B. DRIVE (
9
)
R. DRIVE (
9
)
G.DRIVE (
9
)
REMOTE CONTROL UNIT
NTSC3.58
1. DRIVE
60 Hz
(R)
(G)
**
**
(B)
**
V/C
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT