SHARP 25VTK100 Service Manual

25VT-K100
25VT-CK10

SERVICE MANUAL

S58Q325VTK100

TV/VCR COMBINATION

Chassis No. VN-80

25VT-K100

MODELS

In the interests of user-safety (Required by safety regulations in some countries ) the set should be restored to its
original condition and only parts identical to those specified should be used.

25VT-CK10

CONTENTS

Page

æ IMPORTANT SERVICE SAFETY PRECAUTION .....................................................................................2

æ ELECTRICAL SPECIFICATIONS .............................................................................................................6

æ LOCATION OF USER’S CONTROL .........................................................................................................7

æ DISASSEMBL Y AND REASSEMBLY ..................................................................................................... ..9

æ INSTALLATION AND SERVICE INSTRUCTIONS..................................................................................12

æ PRECAUTIONS IN REASSEMBLING
æ FUNCTION OF MAJOR MECHANICAL PARTS
æ ADJUSTMENT, REPLACEMENT AND ASSEMBLY OF MECHANICAL UNITS

(Refer to 13VT-J100 Service Manual)

æ ADJUSTMENT OF THE VCR ELECTRICAL CIRCUITRY
æ TROUBLESHOOTING

æ TROUBLESHOOTING OF TV SECTION ...............................................................................................17

æ CHASSIS LAYOUT .................................................................................................................................20

æ BLOCK DIAGRAM OF TV SECTION .....................................................................................................23

æ BLOCK DIAGRAM OF VCR SECTION

æ OVERALL SCHEMATIC DIAGRAM........................................................................................................27

æ DESCRIPTION OF SCHEMATIC DIAGRAM..........................................................................................31

æ PRINTED WIRING BOARD ASSEMBLIES ............................................................................................45

æ REPLACEMENT PARTS LIST................................................................................................................51

æ PACKING OF THE SET..........................................................................................................................70

(Refer to 13VT-J100 Service Manual)

(Refer to 13VT -J100 Ser vice Manual)

(Refer to 13VT-J100 Service Manual)

(Refer to 13VT-J100 Service Manual)

(Refer to 13VT-J100 Service Manual)

SHARP CORPORATION

This document has been published to be used for
after sales service only.
The contents are subject to change without notice.

1

25VT-K100
25VT-CK10

IMPORTANT SERVICE SAFETY PRECAUTION

Service work should be performed only by qualified service technicians who are thor­oughly familiar with all safety checks and servicing guidelines which follow:

WARNING

1. For continued safety, no modification of any circuit
should be attempted.

2. Disconnect AC power before servicing.

3. Semiconductor heat sinks are potential shock
hazards when the chassis is operating.

4. The chassis in this receiver has two ground systems
which are separated by insulation material. The non­isolated (hot) ground system is for the B+ voltage
regulator circuit and the horizontal output circuit.The
isolated ground system is for the low B+ DC voltages
and the secondary circuit of the high voltage
transformer.
To prevent electrical shock use an isolation
transformer between the line cord and power
receptacle, when servicing this chassis.

CAUTION: FOR CONTINUED
PROTECTION AGAINST A
RISKOF FIRE, REPLACE

4A 125V

ONLY WITH SAME TYPE 4A­125V FUSE.

SERVICING OF HIGH VOLTAGE SYSTEM
AND PICTURE TUBE

When servicing the high voltage system, re­move the static charge by connecting a 10k
ohm resistor in series with an insulated wire
(such as a test probe) between the picture
tube ground and the anode lead. (AC line
cord should be disconnected from AC out­let.)

1. Note that the picture tube in this receiver employs
integral implosion protection.

2. Replace with tube of the same type number for
continued safety.

3. Do not lift picture tube by the neck.

4. Handle the picture tube only when wearing
shatterproof goggles and after discharging the high
voltage anode completely.

X-RADIATION AND HIGH VOLTAGE LIMITS

1. Be sure all service personnel are aware of the
procedures and instructions covering X-radiation. The
only potential source of X-ray in current solid state
TV receivers is the picture tube. However , the picture
tube does not emit measurable X-Ray radiation if the
high voltage is as specified in the "High Voltage
Check" instructions.
It is only when high voltage is excessive that X­radiation is capable of penetrating the shell of the
picture tube including the lead in glass material. The
important precaution is to keep the high voltage below
the maximum level specified.

2. It is essential that servicepersonal have available at
all times an accurate high voltage meter.
The calibration of this meter should be checked
periodically.

3. High voltage should always be kept at the rated value

−no higher. Operation at higher voltages may cause
a failure of the picture tube or high voltage circuitry
and; also under certain conditions, may produce
radiation excess specitications.

4. When the high voltage regulator is operating properly
there is no possibility of an X-radiation problem. Every
time a color chassis is serviced, the brightness
should be tested while monitoring the high voltage
with a meter to be certain that the high voltage does
not exceed the specified value and that it is regulating
correctly .

5. Do not use a picture tube other than that specified or
make unrecommended circuit modifications to the
high voltage circuitry.

6. When trouble shooting and taking test measurements
on a receiver with excessive high voltage, avoid being
unnecessarily close to the receiver.
Do not operate the receiver longer than is necessary
to locate the cause of excessive voltage.

2

2

2

2

IMPORTANT SERVICE SAFETY PRECAUTION

(Continued)

25VT-K100
25VT-CK10

BEFORE RETURNING THE RECEIVER
(Fire & Shock Hazard)

Before returning the receiver to the user, perform
the following safety checks.

1. Inspect all lead dress to make certain that leads are
not pinched or that hardware is not lodged between
the chassis and other metal parts in the receiver.

2. Inspect all protective devices such as non-metallic
control knobs, insulating materials, cabinet backs,
adjustment and compartment covers or shields,
isolation resistor-capacity networks, mechanical
insulators, etc.

3. To be sure that no shock hazard exists, check for
leakage current in the following manner.

» Plug the AC cord directly into a 120 volt AC outlet,

using reverse polarity (Do not use an isolation
transformer for this test).

» Using to clip leads, connect a 1.5k ohm, 10 watt

resistor paralleled by a 0.15µF capacitor in series
with all exposed metal cabinet parts and a known
earth ground, such as electrical conduit or electrical
ground connected to earth ground.

» Use an AC voltmeter having with 5000 ohm per volt,

or higher, sensitivity to measure the AC voltage drop
across the resistor.

» Connect the resistor connection to all exposed metal

parts having a return to the chassis
(antenna, metal cabinet, screw heads, knobs and
control shafts, escutcheon, etc.) and measure the AC
voltage drop across the resistor.
AII check must be repeated with the AC line cord
plug connection reversed. (IF necessary, a non­polarized adapter plug must be used only for the
purpose of completing these check.)
Any current measured must not exceed 0.5 milliamp.
Any measurements not within the limits outlined
above are indicative of a potential shock hazard and
corrective action must be taken before returning the
instrument to the customer.

AC

VOLTMETER

1.5k ohm
10W

0.15µF

TEST PROBE

TO EXPOSED

METAL PARTS

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CONNECT TO
KNOWN EARTH
GROUND

SAFETY NOTICE

Many electrical and mechanical parts in television
receivers have special safety-related characteristics.
These characteristics are often not evident from visual
inspection, nor can protection afforded by them be
necessarily increased by using replacement components
rated for higher voltage, wattage, etc.
Replacement parts which have these special
safety characteristics are identified in this manual;
electrical components having such features are identified
by " å " and shaded areas in the Replacement Parts
Lists and Schematic Diagrams.

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234567890123456789012345678901212345678901234567890123456789012123456789012345678901234567890121

For continued protection, replacement parts must be
identical to those used in the original circuit. The use of
a substitute replacement parts which do not have the
same safety characteristics as the factory recommended
replacement parts shown in this service manual, may
create shock, fire, X-radiation or other hazards.

3

25VT-K100
25VT-CK10

PRECAUTIONS A PRENDRE LORS DE LA REPARATION

Ne peut effectuer la réparation qu' un technicien spécialisé qui s'est parfaitement
accoutumé à toute vérification de sécurité et aux conseils suivants.

AVERTISSEMENT

1. N'entreprendre aucune modification de tout circuit.
C'est dangereux.

2. Débrancher le récepteur avant toute réparation.

3. Les déversoirs thermiques à semi-conducteurs
peuvent présenter un danger de choc électrique
lorsque le réceqteur est en marche.

4. Le châssis de ce récepteur a deux systèmes de mise
à la terre qui sont séparés par un matériau isolant.
Le système de mise à la terre non-isolée (chaud) est
pour le circuit du régulateur de tension B+ et le circuit
de sortie horizontale. Le système de mise à la terre
isolé est pour les basses tensions C. C. B+ et le circuit
secondaire du transformateur de haute tension.

PRECAUTION:POUR LA
PROTECTION CONTINUE
CONTRE LES RISQUES

4A 125V

D'INCENDIE, REMPLACER LE
FUSIBLE PAR UN FUSIBLE DE
MEME TYPE 4A-125V.

REPARA TION DU SYSTEME A HAUTE TEN­SION ET DU TUBE-IMAGE

Lors de la réparation de ce systéme,
supprimer la charge statique en branchant
une résistance de 10 kΩ en série a vec un fil
isolé (comme une sonde d'essai) entre la
mise à la terre du tube-image et le fil
d'anodel. (Le cor den d'alimentation doit être
retiré de la prise murale.)

1. Il est à noter que le tube-image de ce récepteur est
intégralement protégé contre l'implosion.

2. Par mesure de sécurité, changer le tube-image pour
un tube du même numéro de type.

3. Ne pas lever le tube-image par son col.

4. Ne manipuler le tube-image qu'en porant des lunettes
incassables et qu'après avoir déchargé totalement
la haute tension.

LIMITES DES RADIATIONS X ET DE LA
HA UTE TENSION

1. Tout le personnel réparateur doit être instruit des
instructions et procédés relatifs aux radiations X.
Le tube-image, seule source de rayons X dons les
téleviseurs transistorisés, n'émet pourtant pas de
rayons mesurables si la haute tension est maintenue
à un niveau préconisé dans la section "Vérification
de la haute tension".
C'est seulement quand la haute tension est excessive
que les rayons X peuvent entrer dans l'enveloppe du
tube-image y compris le conducteur de verre. Il est
important de maintenir la haute tension en-dessous
du niveau spécifié.

2. Il est essentiel que le réparateur ait sous la main un
voltmètre à haute tension qui doit être périodiquement
étalonné.

3. La haute tension doit toujours être maintenue à la
valeur de régime-et pas plus haute. L'opération à des
tensions plus élevées peut entraîner une panne du
tube-image ou du circuit à haute tension et, dans
certaines conditions, peut entraîner une radiation
dépassant les niveaux préscrits.

4. Quand le régulateur à haute tension fonctionne
correctement, il n'y a aucun problème de radiation
X. Chaque fois qu'un châssis couleurs est réparé, la
luminosité doit être examinée bout en contrôlant la
haute tension à l'aide d'un voltmètre pour s'assurer
que la haute tension ne dépasse pas la valeur
spécifiée et qu'elle soit correctement réglée.

5. Ne pas utiliser un tube-image autre que celui spécifié
et ne pas effectuer de modifications déconseillées
du circuit à haute tension.

6. Lors de la recherche des pannes et des mesures
d'essai sur un récepteur qui présente une haute
tension excessive, éviter de s'approcher inutilement
du récepteur.
Ne pas faire fonctionner le récepteur plus longtemps
que nécessaire pour localiser la cause de la tension
excessive.

4

25VT-K100

2
2

25VT-CK10

PRECAUTIONS A PRENDRE LORS DE LA REPARATION

(Suite)

VERIFICATIONS CONTRE L'INCEN-DIE ET
LE CHOC ELECTRIQUE

Avant de rendre le récepteur à l'utilisateur, effectuer
les vérifications suivantes.

1. Inspecter tous les faisceaux de câbles pour s'assurer
que les fils ne soient pas pincés ou qu'un outil ne soit
pas placé entre le châssis et les autres pièces
métalliques du récepteur.

2. Inspecter tous les dispositifs de protection comme
les boutons de commande non-métalliques, les
isolants, le dos du coffret, les couvercles ou blindages
de réglage et de compartiment, les réseaux de
résistance-capacité, les isolateurs mécaniques, etc.

3. S'assurer qu'il n'y ait pas de danger d'électrocution
en vérifiant la fuite de courant, de la facon suivante:

» Brancher le cordon d'alimentation directem-ent à une

prise de courant de 120V. (Ne pas utiliser de
transformateur d'isolation pour cet essai).

» A l'aide de deux fils à pinces, brancher une résistance

de 1,5 kΩ 10 watts en parallèle avec un condensateur
de 0,15µF en série avec toutes les pièces métalliques
exposées du coffret et une terre connue comme une
conduite électrique ou une prise de terre branchée à
la terre.

» Utiliser un voltmètre CA d'une sensibilité d'au moins

5000Ω/V pour mesurer la chute de tension en travers
de la résistance.

» Toucher avec la sonde d'essai les pièces métalliques

exposées qui présentent une voie de retour au
châssis (antenne, coffret métallique, tête des vis,
arbres de commande et des boutons, écusson, etc.)
et mesurer la chute de tension CA en-travers de la
résistance.
Toutes les vérifications doivent être refaites après
avoir inversé la fiche du cordon d'alimentation. (Si
nécessaire, une prise d'adpatation non polarisée peut
être utilisée dans le but de terminer ces vérifications.)
Tous les courants mesurés ne doivent pas dépasser
0,5 mA.
Dans le cas contraire, il y a une possibilité de choc
électrique qui doit être supprimée avant de rendre le
récepteur au client.

AC

Voltmètre CA

VOLTMETER

1.5k ohm
10W

0.15µF

SONDE D'ESSAI

AUX PIECES

TO EXPOSED

METALLIQUES
METAL PARTS

EXPOSEES

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BRANCHER A UNE

CONNECT TO

TERRE CONNUE

KNOWN EARTH
GROUND

AVIS POUR LA SECURITE

De nombreuses pièces, électriques et mécaniques, dans
les téléviseurs présentent des caractéristiques spéciales
relatives à la sécurité, qui ne sont souvent pas évidentes
à vue. Le degré de protection ne peut pas être
nécessairement augmentée en utilisant des pièces de
remplacement étalonnées pour haute tension,
puissance, etc.
Les pièces de remplacement qui présentent ces
caractéristiques sont identifiées dans ce manuel; les
pièces électriques qui présentent ces particularités sont

234567890123456789012345678901212345678901234567890123456789012123456789012345678901234567890121

identifiées par la marque " å " et hachurées dans la
liste des pièces de remplacement et les diagrammes
schématiques.
Pour assurer la protection, ces pièces doivent être
identiques à celles utilisées dans le circuit d'origine.
L'utilisation de pièces qui n'ont pas les mêmes
caractéristiques que les pièces recommandées par
l'usine, indiquées dans ce manuel, peut provoquer des
électrocutions, incendies, radiations X ou autres
accidents.

5

25VT-K100
25VT-CK10

VHF/UHF ANTENNA INPUT IMPEDANCE: 75 ohm unbalanced

ELECTRICAL SPECIFICATIONS

TV SECTION

POWER INPUT: 120 V AC 60 Hz

POWER RATING: 110W

PICTURE SIZE

Width: 63.4cm

Height: 58.8cm

Depth: 51.2cm

CONVERGENCE: Magnetic

SWEEP DEFLECTION: Magnetic

FOCUS: Hi-Bi-Potential Electrostatic

INTERMEDIATE FREQUENCIES

Picture IF Carrier Frequency: 45.75 MHz

Sound IF Carrier Frequency: 41.25 MHz

Color Sub-Carrier Frequency: 42.17 MHz (Nominal)

AUDIO POWER OUTPUT RATING: 1.3W (at 10% Distortion)

SPEAKER

Size: 8cm (3")P.M.,0.34 oz. Magnet

V oice Coil Impedance: 8 ohm at 400 Hz

TUNING RANGES

VHF-Channels: 2 thru 13

UHF -Channels: 14 thru 69

CATV Channels: 1,14 thru 125 (EIA,Channel Plan)

VCR SECTION

Maximum Recording Time: (SP)160min (T-160)

Format: VHS Standard

Video Recording System: Rotary Two-Head Helical Scanning

Number of Video Heads: 2 pcs.

Video Signal Standard: NTSC Color System

Tape Width: 12.7mm (1/2inch)

Tape Speed: (SP)33.35mm/sec (1.31i.p.s)

(LP)16.67mm/sec (0.66i.p.s)
Play back only
(EP)11.12mm/sec (0.44i.p.s)

(EP)480min (T-160)
Video Input: 0.5 to 2.0 Vp-p, 75 ohm unbalanced
Audio Input: -8dB, 47k ohm unbalanced (0 dB-0.775 Vrms)

Operating Temperature: 5°C to 40°C (41°F to 104°F)

Storage Temperature: -20°C to 60°C (-4°F to 140°F)

Specifications are subject to change without prior notice.

6

LOCATION OF USER'S CONTROL

25VT-K100
25VT-CK10

7

25VT-K100
25VT-CK10

LOCATION OF USER'S CONTROL (Continued)

Location Of Control’s Buttons (Remote Control)

8

25VT-K100
25VT-CK10

DISASSEMBLY AND REASSEMBLY

1. Remove the 6 rear cover fixing screws and detach the rear cover.

2. Take out the anode cap, CRT PWB, connectors K,M and RC, coating ground SP chip, fixing screws and others.

3. Remove the 2 main PWB fixing screws and take out the main PWB unit and the VCR unit.

4. Remove the 7 VCR fixing screws, and detach the shielding case.

9

25VT-K100
25VT-CK10

DISASSEMBLY AND REASSEMBLY (Continued)

5. Remove the 4 cassette housing control fixing screws, and detach the cassette housing control.

6. Remove the 4 mechanism chassis fixing screws, and detach the mechanism chassis PWB.

7. Remove the 8 main PWB fixing screws, and detach the main PWB.

10

25VT-K100
25VT-CK10

DISASSEMBLY AND REASSEMBLY (Continued)

For servicing any of the components inside, disconnect the lead dressing holder. Position the main PWB unit upright
as shown below and connect the leads for starting the services.

Note: Fit the VCR unit into the front cabinet with the

front flap door tilted at 70~80°.

70~80°

11

25VT-K100
25VT-CK10

INSTALLATION AND SERVICE INSTRUCTIONS

Notes: (1) When performing any adjustments to resistor controls and transformers use non-metallic

screwdriver or TV alignment tools.

(2) Before performing adjustment, TV set must be on at least 15 minutes.

CIRCUIT PROTECTION

The receiver is protected by a 4.0A fuse (F701), mounted
on PWB-A, wired into one side of the AC line input.

X-RADIATION PROTECTOR CIR­CUIT TEST

After service has been performed on the horizontal
deflection system, high voltage system, or B+ system,
test the X-radiation protector circuit to ascertain proper
operation as follows:

1. Apply 120V AC using a variac transformer for
accurate input voltage.

2. Allow for warm up and using the remote controller,
set the brightness level and contrast level to
maximum.

3. Check the voltage of test point TP653. (It’s voltage
should be about 10.5V DC.)

4. Apply external 13.5V DC at TP653 by using an
external DC supply , The increased voltage will cause
the horizontal oscillator to stop and the TV to shut
off.

5. To re-start the osillator, remove the external DC
power supply and short together TP651 and TP652.
Once the TV set operates normally again, remove
the short between TP651 and TP652.

HIGH V OL T A GE CHECK

High voltage is not adjustable but must be checked
to verify that the receiver is operating within safe
and efficient design limitations as specified checks
should be as follows:

1. Connect an accurate high voltage meter between
ground and anode.

2. Operate receiver for at least 15 minutes at 120V AC
line voltage, with strong air signal or properly tuned
in test signal.

3. Set to Service mode on, service item: MUTE, and
bus data 1(Y-mute on).

4. The voltage should be approximately 28.1kV (at zero
beam).
If a correct reading cannot be obtained, check
circuitry for malfunctioning components.
Upon completion of voltage check, readjust screen
control for proper operation and set S851 to center
position (cut off mode).

12

25VT-K100

SERVICEMODE:01
SUB-COLOR=64

25VT-CK10

The SHARP TV/VCR COMBINATION have most of the analog setup adjustments eliminated. Coil and variable
resistor adjustments are now performed digitally by using the remote transmitter or set’s volume and channel
change function buttons.
Note: There are still a few analog adjustments in the J-series such as 120V adjust, focus, master screen

voltage and coils in the picture if/detector circuit.
Follow the steps below whenever service adjustment is required. See table “B” to determine if service
adjustments are required.

1.Service mode -

Before putting unit into the service mode, check, that
customer adjustments are in the normal mode. use
the reset function in the video adjust menu to ensure
customer controls are in their proper ( reset ) position.

To enter the service mode -

While pressing the Ch-up (S2507) button, Plug the
AC cord into a wall socket. Now the TV set is switched
on and enters the service mode.
When successfully entered, the service mode will be
displayed as shown in Figure A. The “SERVICE
MODE” figure the top line stands for service
adjustment item and data (see Figure A.).

To exit service mode-

Turn off the power or unplug the set.

2. Service item selection

Once in the service mode, press the channel up or
channel down button on the remote transmitter or at
the set.
(Table-A.) . Select the item you wish to adjust.

3.Data number selection

Pess the volume up or down button to adjust the data
number in the upper left hand side of the screen.

PICTURE:16

Figure A.

02

13

25VT-K100
25VT-CK10

Table-A

ADJUSTMENT

ITEM

PICTURE 16 0~63
TINT 39 0~77
COLOR 13 0~63
BRIGHT 32 0~63
SHARP 7 0~13
V -PHASE 0 0~7
H-PHASE 20 0~31
RF-AGC 32 0~63
V-AMP 32 0~63
PIF-VCO 40 0~127
R CUT-OFF 0 0~255
G CUT -OFF 0 0~255
B CUT-OFF 0 0~255
G GAIN 128 0~255
B GAIN 128 0~255
MUTE 0 0~2 "0"=Normal raster,"1"=no Y "2"=No Vertical
BALANCE 32 0~63
TEXT POSITION 28 0~128
TEXT PICTURE 20 0~1
CCD LEVEL 7 0~10
OPTION 1 0~3

INTIAL VALUE RANGE

DATA

ADJUSTMENT

COMMENTS

*No adjustment is required due to proper setting being made by IC3101 automatically.

Table-B

PART
REPLACED

IC2001 X

IC401 X

IC2101 X

CRT X

NECESSARY UNNECESSARY

ADJUSTMENT

NOTE

Data is stored in IC2101.
The adjustment is needed to compensate for characteristics

of parts including IC401.
Initial setting values are written from IC2001.Adjust for best

results.
Adjust items related to picture tube only.

14

25VT-K100
25VT-CK10

SERVICE ADJUSTMENT

VCO Adjustment

1. Connect a digital voltmeter between pin(44) of IC401
and ground.

2. Select a good local channel.

3. Enter the service mode. select adjustment “PIF­VCO” and data value “64”.

4. Adjust the VCO coil T201 so that the digital voltmeter
reads 2.5 volts.

5. Adjustment is complete, remove the voltmeter,
return to “normal” mode.

RF AGC Adjustment

1. Have unit receive a good local channel.

2. Enter the service mode and select service
adjustment “RF-AGC”.

3. Set the data value to point where no noise or beat
appears.

4. Select another channel to confirm that no noise or
beat appears.

Note 1: You will have to come out of the service

mode to select another channel.

Note 2: Setting the data to “0” will produce a

black raster.

Screen adjustment

1. Select a good local channel.

2. Enter the service mode and select service
adjustment “COLOR” and set the data value to “0”
to set the color level to minimum.You may skip this
step if you selected a B/W picture or monoscope
pattern.

3. Select service adjustment “MUTE” and adjust the
data value to “1” this turns off the luminance signal
(Y-mute) .

4. Select service adjustment “BRIGHT” and adjust data
value to "28".

5. Adjust the master screen control untill raster darkens
to the point where raster is barely seen.

6. Adjust service adjustments “R-CUT OFF” red,”G­CUT OFF" green and “B-CUT OFF” blue to obtain
a good grey scale with normal whites at low
brightness level.

7. Select service adjustment “MUTE” and reset data
to” 0" Select service adjustment “COLOR” and reset
data to obtain normal color level.

8. Remove digital voltmeter. reset master screen
control to obtain normal brightness range.

White balance adjustment

1. Have unit receive a good local channel.

2. Enter the service mode. select service adjustment
“COLOR” and set to “0” ( minimum color) . “COLOR”
does not have to be adjusted if you selected a B/W
picture or monoscope pattern.

3. Alternately adjust service adjustment data of “G
GAIN” and “B GAIN” untill a good grey scale with
normal whites is obtained.

4. Select service adjustment “COLOR”and adjust data
to obtain normal color level.

Sub-picture adjustment

1. Have unit receive a good local channel.

2. Make sure the customer picture control is set to
maximum.

3. Enter the service mode and select service
adjustment “PICTURE”.

4. Adjust the data value to achieve normal contrast
range.

Sub-Tint Adjustment

1. Have unit receive a good local channel.

2. Set customer tint control to center of it’s range.

3. Enter the service mode and select service
adjustment “TINT”.

4. Adjust “TINT” data value to obtain normal flesh tones.

Sub-color adjustment

1. Have unit receive a good local channel.

2. Make sure the customer color control is set to
center position .

3. Enter the service mode and select service
adjustment “COLOR”.

4. Adjust “COLOR”data value to obtain normal color
level.

Sub-brightness adjustment

1. Have unit receive a good local channel.

2. Make sure the customer brightness control is set to
center position.

3. Enter the service mode and select service
adjustment “BRIGHT”.

4. Adjust “BRIGHT”data value to obtain normal
brightness level.

15

25VT-K100
25VT-CK10

Vertical-size adjustment

1. Have unit receive a good local channel.

2. Enter the service mode and select service
adjustment “V-AMP”.

3. While observing the top and bottom of the screen,
adjust “V-AMP” data value to proper vertical size and
linearity.

Horizontal position adjustment

1. Have unit receive a good local channel.

2. Enter the service mode and select service adjustment
“H-PHASE”.

3. Adjust “H-PHASE” data value so that picture is
centered.

Caption position adjustment (hori­zontal)

1. Have unit receive a good local channel.

2. Enter the service mode and select service adjustment
“TEXT POSITION”.

3. A black text box appears on the screen (see
Figure B.) .

4. Adjust “TEXT POSITION” data value so that text box
is positioned in the center of the screen.

Figure B.

16

TROUBLESHOOTING OF TV SECTION

25VT-K100
25VT-CK10

FLOW CHART NO.2-2

Blown out

NO RASTER

F701 Check

Replace the Fuse

Normal

The Fuse is again

blown out

T701 Pin (7) voltage

check about: 170V DC

at 120V AC

Abnormal

IC701, Check

Normal

R701

Normal

D701, D702, D703,

D704, D705

side)

±

Normal

voltage check about:

+

B

128.5V (C730

Abnormal

IC701, D727

Abnomal

IC401 (iX2933CE)

Normal

CRT connector

GC1~GC5 bias check

Normal

R603, Q601,

Q612

C854

FLOW CHART NO.2-1

Connect AC cord.

NO

YES

Set not operating

Is AC cord connected?

AC cord broken.

NO

YES

Is 120V AC applied to

line between (H) and

(C) of P702 ?

YES

Is 170V DC applied to

C705?

NO

Check R708 and

IC701.

Check IC701 and

adjacent parts

NO

Is 16V DC applied to

Check D701 thru

NO

YES

pin (4) of IC701 ?

Does pulse waveform

exist at line between (2)

and (3) of IC701 ?

D704, L701,

R701 and F701.

17

YES

Check T701, and

adjacent parts.