JVC AV-21L91-BK User manual

SERVICE MANUAL
AV-21L91
AV-25L91
AV-29L91
COLOUR TELEVISION
BASIC CHASSIS
CH
No. 51898
Nov. 2001
COPYRIGHT © 2001 VICTOR COMPANY OF JAPAN, LTD.
AV-21L91
(-BK)
AV-25L91 (-BK)
AV-29L91 (-BK)
RM-C353-1CRM-C353-1C
[AV-21L91
(-BK)
, AV-25L91
(-BK)
] [AV-29L91
(-BK)
]
RM-C353 REMOTE CONTROL UNIT
DISPLAY
MENU
POWER
CHANNEL VOLUME
SYSTEM
COLOUR
OFF TIMER
TV/VIDEO
PICTURE MODE
CHANNEL SCAN
ECO SENSOR
SOUND MUTING
RETURN
123
456
78
0
9
-/--
I/II
RM-C353 REMOTE CONTROL UNIT
DISPLAY
MENU
POWER
CHANNEL VOLUME
SYSTEM
COLOUR
OFF TIMER
TV/VIDEO
PICTURE MODE
CHANNEL SCAN
ECO SENSOR
SOUND MUTING
RETURN
123
456
78
0
9
-/--
I/II
tu2522 086-5306051 087-4915026

2 No. 51898
AV-21L91
AV-25L91
AV-29L91
Dimensions (W ×H ×D) 59.8cm ×46.8cm ×47.15cm 68.2cm ×53.84cm ×47.75cm 73.2cm ×58.8cm ×51.8cm
Mass 24kg 30kg 47kg
TV RF System B, G, I, D, K, M
Colour System TV Mode PAL / SECAM / NTSC3.58 / NTSC4.43
VIDEO Mode PAL / SECAM / NTSC3.58 / NTSC4.43
Stereo System A2 NICAM
Receiving Frequency VHF (VL) 43.75MHz – 142.25MHz 46.25MHz – 140.25MHz
VHF (VH) 142.28MHz – 428.75MHz 147.25MHz – 423.25MHz
UHF 428.78MHz – 865.75MHz 431.25MHz – 863.25MHz
CATV ●Cable TVs of Mid (X-Z, S1-S10)
Super (S11-S20) & Hyper (S21-S41) bands receivable
Intermediate VIF Carrier 38.0MHz
Frequency 31.5MHz (6.5MHz)
SIF Carrier 32.0MHz (6.0MHz)
32.5MHz (5.5MHz)
Colour Sub Carrier Frequency PAL (4.43MHz), SECAM (4.40625MHz / 4.25MHz)
NTSC (3.58MHz / 4.43MHz)
Aerial Input Terminal 75ØUnbalanced
Power Input AC110 – 240V, 50 / 60Hz
Power Consumption 115W (Max.) / 75W (Avg.) 150W (Max.) / 90W (Avg.) 172W(Max.)/108W(Avg.)
Picture Tube (Vsible size) 51cm measured diagonally 60cm measured diagonally 68cm measured diagonally
High Voltage (at cut-off in service mode) 29kV ± 1kV 31kV ± 1kV 32kV +1/–1.5kV
Speaker 5 ×12cm Oval type ×2
Audio Output 5W + 5W 7W + 7W
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 (400Hz when modulated 100%) (RCA pin jack)
Headphone Jack Stereo mini jack (3.5φ)
Remote Control Unit RM-C353-1C
(Battery size: AA/R06/UM-3 ×2)
SPECIFICATIONS
Items
Design & specifications are subject to change without notice.
Contents
AV-21L91-BK AV-25L91-BK AV-29L91-BK

AV-21L91
AV-25L91
AV-29L91
No. 51898 3
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 with a measur-
ing apparatus (oscilloscope etc.) the LIVE side GND and ISOLATED
(NEUTRAL) side GND or EARTH side GND at the same time.
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. 51898
AV-21L91
AV-25L91
AV-29L91
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 ~ 240V) 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 op-
timum picture which is easy on the eye.
sBuilt-in OFF TIMER & RETURN +.

AV-21L91
AV-25L91
AV-29L91
No. 51898 5
FUNCTIONS
aREAR PANEL
aFRONT PANEL
[AV-21L91-BK, AV-25L91-BK]
aREMOTE CONTROL UNIT
RM-C353-1C
RM-C353 REMOTE CONTROL UNIT
DISPLAY
MENU
POWER
CHANNEL VOLUME
SYSTEM
COLOUR
OFF TIMER
TV/VIDEO
PICTURE MODE
CHANNEL SCAN
ECO SENSOR
SOUND MUTING
RETURN
123
456
78
0
9
-/--
I/II
[AV-29L91-BK]
L/MONOVR
IN (VIDEO-3)
VIDEO-1
INPUT OUTPUT
COMPONENT
(VIDEO-2)
INPUT
V
MONO
L
/
V
Y
/
V
L
MONO
L
/
C B
RRRC
R

6 No. 51898
AV-21L91
AV-25L91
REMOVING THE REAR COVER
1. Unplug the AC power cord.
2. Remove the 7 or 9 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
DISASSEMBLY PROCEDURE [AV-21L91-BK, AV-25L91-BK]

AV-21L91
AV-25L91
No. 51898 7
Fig.1
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) [AV-21L91-BK]
(×9) [AV-25L91-BK]
Except 21”
model
Except 21”model

8 No. 51898
AV-29L91
REMOVING THE REAR COVER
1. Unplug the AC power cord.
2. Remove the 16 screws marked Åas shown in Fig.2.
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 CHASSIS (CHASSIS BASE AND
CONTROL BASE)
•After removing the rear cover.
1. Slightly raise the both sides of the chassis by hand and remove the
2 claws marked ıunder the chassis from the front cabinet as shown
in Fig.2.
2. Withdraw the chassis backward.
(If necessary, take off the wire clamp, connector’s etc.)
*When conducting a check with power supplied, be sure to confirm
that the CRT earth wire is connected to the CRT Socket PWB and
the Main PWB.
REMOVING THE AV TERMINAL BOARD
•After removing the rear cover.
1. Remove the 4 screws marked Ças shown in Fig.2.
2. When you pull out the AV Terminal board in the direction of arrow
marked Îas shown in Fig.2, it can be removed.
REMOVING THE CONTROL BASE
•After removing the rear cover and the chassis.
1. While pushing down the 2 claws maked ´as shown in Fig. 3.
2. When you pull out the Control base in the direction of arrow maked
Ïas shown in Fig. 3.
(If necessary, take off the wire, connector’s etc.)
REMOVING THE SPEAKER
•After removing the rear cover.
1. Remove the 4 screws marked ˝as shown in Fig.2.
2. Withdraw the speaker backward.
3. 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 chassis. (Refer to REMOVING THE CHASSIS).
2) Erect the chassis vertically so that you can easily check the back
side of the Main PWB.
[CAUTION]
•When erecting the chassis, be careful so that there will be no con-
tacting with other PW Board.
•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.
DISASSEMBLY PROCEDURE [AV-29L91-BK]

AV-29L91
No. 51898 9
Fig.2
CRT
SOCKET
PWB
FRONT CONTROL
PWB (1/2)
FRONT CONTROL PWB (2/2)
MAIN PWB
CHASSIS
BASE
CONTROL BASE
Fig.3
(×4)
PICTURE TUBE
CLAW B
D
C
CLAW B
AV TERMINAL
BOARD
FRONT CABINET
CONTROL BASE
[FRONT SIDE]
CHASSIS
BASE
E
F
(×4)
SPEAKER
G
(×4)
SPEAKER
G
(×4)
REAR COVER
A
(×6)
A
(×1)
A
(×4)
A
(×1)
A
Fig.3

10 No. 51898
AV-21L91
AV-25L91
AV-29L91
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. 4).
2. While keeping the surface of CRT down, mount the TV set on the
CRT change table balanced will as shown in Fig. 5.
3. Remove 4 screws marked by arrows with a box type screwdriver as
shown in Fig. 5.
•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. 6.
•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. 7.
1. Wipe around the anode button with clean and dry cloth. (Fig. 7)
2. Coat silicon grease on the section around the anode button. At this
time, take care so that any silicon greases dose not sticks to the
anode button. (Fig. 8)
夝Silicon grease product No. KS - 650N
Fig. 4
CRT CHANGE TABLE
APPROX.
35cm
CLOTH
Fig. 5
CRT
BOX
TYPE
SCREW
DRIVER
CRT
CHANGE
TABLE
Fig. 6
CRT
CHANGE TABLE
CRT
CABINET
Fig. 7
Anode button
CRT
Silicon grease
coating
Fig. 8
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

AV-21L91
AV-25L91
AV-29L91
No. 51898 11
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
******* **** ***** *****
**** **** *** ***
SYSTEM CONSTANT-I
SELECT BY
OPERATE BY +
-
DISPLAY
COMB
TILT
MULTI
YES
YES
TEXT YES
SUPER BASS NO
LANGUAGE E / R / C
SYSTEM CONSTANT SET 1
SYSTEM
MENU 89
SYSTEM CONSTANT-II
SELECT BY
OPERATE BY +
-
DISPLAY
BILINGUAL
B / B SOUND
YES
NO
NO
TUNER MU
COLOUR AUTO NO
SYSTEM CONSTANT SET 2
MSP
MENU 89
SYSTEM CONSTANT-III
SELECT BY
OPERATE BY +
-
DISPLAY
500 kHz
250 kHz
010
010
010
156.25 kHz 010
31.25 kHz 010
SYSTEM CONSTANT SET 3
LOCK 1 MHz
MENU 89
Fig. 1
Fig. 2
DISPLAY
MENU
POWER
CHANNEL VOLUME
SYSTEM
COLOUR
MODE
OFF TIMER
TV/VIDEO
PICTURE MODE
CHANNEL SCAN
ECO SENSOR
SOUND MUTING
RETURN
I/II
123
456
78
0
9
-/--
MENU
DISPLAY
MENU
MENU +
MENU
PICTURE
MODE

12 No. 51898
AV-21L91
AV-25L91
AV-29L91
Setting item Setting content
Setting value
YES NO
YES NO
YES PSEUDO NO
YES NO
YES NO
YES NO
MU MA
YES NO
000 024
000 024
000 024
000 024
000 024
AV-29L91-BKAV-25L91-BKAV-21L91-BK
SYSTEM
COMB
TILT
TEXT
SUPER BASS
LANGUAGE
MSP
BILINGUAL
B/B SOUND
TUNER
COLOUR AUTO
LOCK 1MHz
500KHz
250KHz
156.25KHz
31.25KHz
MULTI
NO
NO
NO
NO
E/T
YES
NO
NO
MU
NO
020
020
020
015
015
YES
YES
MULTI TRIPLE
VIET PAL
EASTERN UKRANIAN RUSSIAN
NO PAN EURO ARABIC
E/T E
SETTING OF SYSTEM CONSTANT SET
Table 1

AV-21L91
AV-25L91
AV-29L91
No. 51898 13
Setting item Setting value
SUB POWER ON
CHANNEL POSITION 1 POSITION
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 THAI
AI VOLUME ON
ON SCREEN DISPLAY POSITION INDICATION
COLOUR SYSTEM PAL
SOUND SYSTEM B/G
STEREO MODE STEREO
PICTURE MODE-VSM BRIGHT
OFF TIMER 00
ECO SENSOR OFF
BASS CENTRE
TREBLE CENTRE
BALANCE CENTRE
PICTURE TILT 00 [AV-29L91-BK]
USER SETTING VALUES
Table 2

14 No. 51898
AV-21L91
AV-25L91
AV-29L91
1. IF 1. VCO
2. DELAY POINT
2. VC 1. CUTOFF(R/G)
2. DRIVE(R/G/B)
3. BRIGHT
4. CONT
5. COLOUR
6. TINT
7. SHARP
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. COLOUR
3. BRIGHT
4. CONT
5. SHARP
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. ERROR LIMIT
2. A2 ID THR
3. SOUND SYSTEM
6 / 7. PLUG & PLAY(OFF)
Do not adjust
Do not adjust
Do not adjust
Do not adjust
Do not adjust
Table 3

AV-21L91
AV-25L91
AV-29L91
No. 51898 15
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

16 No. 51898
AV-21L91
AV-25L91
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 CENTRE
TINT,COLOUR,BRIGHT,CONT,SHARP CENTRE
MEASURING INSTRUMENT
1. DC voltmeter (or Digital voltmeter)
2. Oscilloscope
3. Signal generator (Pattern generator) [PAL/SECAM/NTSC]
4. Remote control unit
ADJUSTMENT ITEMS
•B1 POWER SUPPLY
•FOCUS adjustment
•IF circuit adjustment
VCO (CW) adjustment
DELAY POINT adjustment
•VC (VIDEO/CHROMA) circuit adjustment
WHITE BALANCE (Low light) adjustment
WHITE BALANCE (High light) adjustment
SUB BRIGHT adjustment
SUB CONT adjustment
SUB COLOUR adjustment
SUB TINT adjustment
•DEFLECTION circuit adjustment
VER. SLOPE adjustment
VER. POSITION adjustment
V. ZOOM adjustment
HOR. POSITION adjustment
HOR. WIDTH adjustment
EW-PIN adjustment
EW-TRAPEZ adjustment
VER. SCURVE adjustment
UP CORNER and DW CORNER adjustment
HOR. PARALL adjustment
HOR. BOW adjustment
•User mode setting position
•VSM PRESET adjustment
•PRESET adjustment
•AUDIO adjustment
•PURITY and CONVERGENCE adjustments
PURITY adjustment
STATIC CONVERGENCE adjustment
DYNAMIC CONVERGENCE adjustment

AV-21L91
AV-25L91
No. 51898 17
ADJUSTMENT LOCATIONS [AV-21L91-BK, AV-25L91-BK]
E1
TOP
CRT EARTH
(SOLDER SIDE)
(BRAIDED ASS'Y)
U
TP-47G
HV
41
GND B1
UPPER : FOCUS (F1)
IC702
CRT SOCKET PWB
(Within MAIN PWB ASS’Y)
T
61
41
FRONT
AV IN/OUT
HVT
MAIN PWB
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

18 No. 51898
AV-29L91
ADJUSTMENT LOCATIONS [AV-29L91-BK]
E1
TOP
CRT EARTH
(BRAIDED ASS'Y)
U
TP-47B
TP-47G
HV
61
GND B1
UPPER : FOCUS (F1)
MIDDLE : FOCUS (F2)
IC702
CRT SOCKET PWB
(SOLDER SIDE)
T
81
16
FRONT
FRONT
FRONT
AV IN/OUT
HVT
MAIN PWB
FRONT CONTROL PWB(1/2) FRONT CONTROL PWB(2/2)
J304 J303 J302
S804
S805
S806 S802
S803S801 J801
CN003
CN002
CN00A
CN001
CN002
PW
POWER
SW.
R
W
S901
S801 : CH UP +
S802 : CH DOWN –
S803 : MENU
S804 : TV/VIDEO
S805 : VOL UP+
S806 : VOL DOWN –
1
18
16
5
S
U
LOWER : SCREEN
TU001
J804J801 J802 J803
IC701
Z
CN001
W
T
DEG
TP-E

AV-21L91
AV-25L91
AV-29L91
No. 51898 19
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 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 ~5 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.

20 No. 51898
AV-21L91
AV-25L91
AV-29L91
Fig. 1
1-2 : SELECT DISPLAY : EXIT
SUB MENU 1. IF
SUB MENU 2. VC
50 Hz
Setting item
1. ERROR LIMIT
2. A2 ID THR
3. SOUND SYSTEM
Setting item
1. CUTOFF (R/G)
2. DRIVE (R/G/B)
3. BRIGHT
4. CONT
5. COLOUR
6. TINT
7. SHARP
8. YDELAY
4 : 3 / 16 : 9, 50Hz / 60Hz
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
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
******* **** ***** *****
**** **** *** ***
AUDIO
1. ERROR LIMIT
C AD BITS
NICAM ERROR
*****
MHz
*********
****
****
SUB MENU 6.AUDIO
89: SELECT
- /+: OPERATE DISPLAY : EXIT
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
SUB MENU 3. DEF
50Hz
1. VCO
2. DELAY POINT
IF
PAL
1. CUTOFF (R)
(G)
**
**
V/C
PAL
1. VER. SLOPE
**
DEF 4 : 3
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
SUB MENU 5. PRESET
PAL
1. CB
*
PRESET 50Hz B/G
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
SUB MENU 4. VSM PRESET
TINT
**
COLOUR
**
BRIGHT
**
CONT
**
SHARP
**
BRIGHT
MENU 89: SELECT
MENU
- /+: OPERATE DISPLAY : EXIT
VCO (CW)
*****
MHz
DISPLAY : EXIT
TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW
DELAY POINT VHF
AGC TAKE-OVER
**
- /+: 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. COLOUR
3. BRIGHT
4. CONT
5. SHARP
Setting item