Sharp 25C340 User manual

1
25C340
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.
»ELECTRICAL SPECIFICATIONS ........................................................................................................1
»IMPORTANT SERVICE SAFETY PRECAUTION ................................................................................2
»LOCATION OF USER'S CONTROL ....................................................................................................4
»INSTALLATION AND SERVICE INSTRUCTIONS ...............................................................................5
»CHASSIS LAYOUT ............................................................................................................................11
»BLOCK DIAGRAM .............................................................................................................................12
»SCHEMATIC DIAGRAMS ..................................................................................................................13
»PRINTED WIRING BOARD ASSEMBLIES .......................................................................................19
»REPLACEMENT PARTS LIST ...........................................................................................................22
»PACKING OF THE SET .....................................................................................................................29
Page
SHARP CORPORATION This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
CONTENTS
MODEL
ELECTRICAL SPECIFICATIONS
POWER INPUT..................................................... 120 V AC 60 Hz
POWER RATING ..................................................................105 W
PICTURE SIZE ........................................... 2,032cm2(315sq inch)
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 ..................... 1.5 W+1.5 W (at 10% distortion and
Dual CH Operate)
SPEAKER
SIZE ...................................................................... 8 cm (Round)
VOICE COIL IMPEDANCE............................. 32 ohm at 400 Hz
ANTENNA INPUT IMPEDANCE
VHF/UHF.....................................................75 ohm Unbalanced
TUNING RANGES
VHF-Channels...............................................................2 thru 13
UHF-Channels ............................................................14 thru 69
CATV Channels ...........................................................1 thru 125
(EIA, Channel Plan U.S.A.)
Specifications are subject to change without
prior notice.
25C340
COLORTELEVISION
Chassis No. C/D-BM
SERVICE MANUAL

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25C340
IMPORTANT SERVICE SAFETY PRECAUTION
Service work should be performed only by qualified service technicians who are
thoroughly familiar with all safety checks and the 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 insulating material.The non-
isolated (hot) ground system is for the B+ voltage
regulatorcircuitandthehorizontaloutputcircuit.The
isolatedgroundsystemisforthelowB+ DCvoltages
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
RISK OF FIRE, REPLACE
ONLY WITH SAME TYPE 4A-
125V FUSE.
4A 125V
SERVICING OF HIGH VOLTAGE SYSTEM
AND PICTURETUBE
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 pic-
ture tube ground and the anode lead. (AC
line cord should be disconnected from AC
outlet.)
1. Picturetubeinthisreceiveremploysintegralimplosion
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 HIGHVOLTAGE LIMITS
1. Be sure all service personnel are aware of the
proceduresand instructionscoveringX-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 X-
radiation is capable of penetrating the shell of the
picture tube including the lead in the glass material.
The important precaution is to keep the high voltage
below the maximum level specified.
2. It is essential that servicemen have available at all
times an accurate high voltage meter.
The calibration of this meter should be checked
periodically.
3. Highvoltageshouldalways be keptat the ratedvalue
−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 in exceeding of desirable levels.
4. Whenthe high voltageregulator is operatingproperly
thereis no possibilityof an X-radiationproblem.Every
timea colorchassisis serviced,thebrightness 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. Whentroubleshootingand takingtestmeasurements
ona receiverwith 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.

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25C340
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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 increasedbyusingreplacement 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.
IMPORTANT SERVICE SAFETY PRECAUTION
(Continued)
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,
(Do not use an isolation transformer for this test).
•Using two clip leads, connect a 1.5k ohm, 10 watt
resistorparalleled bya0.15µFcapacitorin serieswith
all exposed metal cabinet parts and a known earth
ground,such aselectrical conduit orelectrical 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.
For continued protection, replacement parts must be
identical to those used in the original circuit.The use of
substitutereplacement partswhichdo nothavethesame
safety characteristics as the factory recommended
replacement parts shown in this service manual, may
create shock, fire, X-radiation or other hazards.
BEFORE RETURNINGTHE RECEIVER
(Fire & Shock Hazard)
Before returning the receiver to the user, perform
the following safety checks.
•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 checks must be repeated with the AC line cord
plug connection reversed. (If necessary, a non-
polarized 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 indicate 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 CONNECT TO
KNOWN EARTH
GROUND

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25C340
LOCATION OF USER'S CONTROL
1 2 3
4 5 6
7 8 9
0 100
POWER
TV
DVD
VCR
MENU MUTE
PAUSE
FLASHBACK
DISPLAY INPUT
TV • CATV • VCR • DVD
STOP REC
REW PLAY FF
CH/SKIP
VOL
—
CH
CH
VOL
+
ENTER
A B C D
PERSONAL PREFERENCE
CATV TV
DVD VCR
InfraredTransmitterWindow
DISPLAY
Press→Displaysreceiving channelfor
four seconds.
Press again →Removes display.
• Temporarily displays receiving
channel when in Closed Caption
mode.
INPUT
Press →Switch to external video
INPUT 1 mode.
Press2times→Switchtoexternalvideo
INPUT 2 mode.
Press 3 times →Switch back to the
original TV mode.
ENTER
Usedinsomeinstances where aCable
Converter Box requires an “enter”
command after selecting channels,
when using the REMOTE KEYPAD
button.
CHANNEL UP/DOWN
( ) Selects next higher channel.
( ) Selects next lower channel.
• Moves the “ ” mark of the MENU
screens.
MUTE
Press →Mutes sound.
Press again →Restores sound.
• CLOSED CAPTION appears when
sound is muted.
Note:
• The above shaded buttons on the Remote Control glow in the dark. To use the glow-in-the-dark display on the remote
control, place it under a fluorescent light or other lighting.
• The phosphorescent material contains no radioactive or toxic material, so it is safe to use.
• The degree of illumination will vary depending on the strength of lighting used.
• The degree of illumination will decrease with time and depending on the temperature.
• The time needed to charge the phosphorescent display will vary depending on the surrounding lighting.
• Sunlight and fluorescent lighting are the most effective when charging the display.
POWER
Press →On.
Press again →Off.
REMOTE KEYPAD
Accesses any channel from keypad.
FLASHBACK
Returns to previous channel.
PERSONAL PREFERENCE
With the Personal Preference buttons,
you can program your favorite
programs by using the 4 categoriesA,
B, C and D. The channels can be
accessed quickly by using these
buttons.
VOLUME UP/DOWN
(+) Increases sound.
(–) Decreases sound.
• In menu mode, changes or selects
the TV adjustments.
MENU
Press →Accesses MAIN MENU.
Press again →Exits MAIN MENU.
CATV/DVD-TV/VCR MODE SELECT
SWITCH
In TV/VCR position, sends power and
channel select commands (Channel
up/downandRandomAccessbuttons)
to the TV and VCR control.
In CATV/DVD position, sends power
and channel select commands to a
cable TV converter and DVD control.
DVD/VCR CONTROL
Basic Remote Control Functions
Front Panel
VOLUME UP/DOWN
(+) Increases sound.
(–) Decreases sound.
CHANNEL UP/DOWN
( ) Selects next higher channel.
( ) Selects next lower channel.
• Press both at the same time to
access the MAIN MENU screen.
POWER
Press →On.
Press again →Off.
SENSOR AREA FOR
REMOTE CONTROL
MENU
Press →Accesses MAIN MENU.
Press again →Exits MAIN MENU.
VIDEO/AUDIO IN2 TERMINALS

5
25C340
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 CIRCUITTEST
After service has been performed on the horizontal
deflection system, high voltage system,B+ system,
test the X-Radiation protection circuit to ascertain
proper operation as follows:
1. Apply120VACusingavariactransformerforaccurate
input voltage.
2. Allow for warm up and adjust all customer controls
for normal picture and sound.
3. Receive a good local channel.
4. Connect a digital voltmeter toTP653 and make sure
that the voltmeter reads 21.9 ±1.4V.
5. Apply external 27.8V DC at TP653 by using an
external DC supply, TV must be shut off.
6. To reset the protector, unplug the AC cord and make
ashort circuit betweenTP651 andTP652.Nowmake
sure that normal picture appears on the screen.
7. If the operation of the horizontal oscillator does not
stop in step 5, the circuit must be repaired before the
set is returned to the customer.
HIGH VOLTAGE 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 of picture tube.
2. Operate receiver for at least 15 minutes at 120V AC
linevoltage,with astrongairsignalor aproperlytuned
in test signal.
3. Enter the service mode and select the service
adjustment "S03" and Bus data "01" (Y-mute on).
4. Thevoltageshouldbeapproximately, 27.8kV (atzero
beam).
Ifa correctreading cannotbe obtained,checkcircuitry
formalfunctioning components. Afterthe voltagetest,
makeY-mute off to the normal mode.
INSTALLATION AND SERVICE INSTRUCTIONS
Note: (1)When performing any adjustments to resistor controls and transformers use non-metallic
screwdrivers or TV alignment tools.
(2)Before performing adjustments, the TV set must be on at least 15 minutes.

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25C340
For adjustments of this model, the bus data is converted to various analog signals by the D/A converter circuit.
Note: There are still a few analog adjustments in this series such as focus and master screen voltage. Follow
the steps below whenever the service adjusment is required.
To enter the service mode and exit service mode.
While pressing the Vol-up and Ch-up buttons at the sametime, plug the AC cord into a wall socket.
Now, the TV set is switched on and enters the service mode.
To exit the service mode, turn the television off by pressing the power button.
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 adjustment menu to ensure customer control are in their proper (reset) position.
2. Service number selection.
In the service mode, you will see the window screen as window 1. There are 4 adjustment categories 2DEF,
3SIGNAL, 4FEATURE, 5FIX VALUE as show in Figure A.
Press CH UP/DOWN button for selection and enter by VOL UP or VOL DOWN.
Press CH UP/DOWN button to select the adjustment item and VOL UP/DOWN
to adjust the data number for each categories.
(OSD disturbance can be erased by R/C display key)
(Note: EEPROM - factory used only)
Figure A: ADJUSTMENT CATEGORIES
Window 2: DEF
DEF
RETURN
RETURN
FIX VALUE
NEXT
FEATURE
D01
D03
D05
RETURN
D02
D04
D06
Window 5: FIXVALUE
Window 1: ADJUSTMENT CATEGORIES
SERVICE MODE
DEF
SIGNAL
FEATURE
FIX VALUE
EEPROM
RETURN
RETURN
Window 3: SIGNAL
SIGNAL S01
S13
RETURN
S02
S14
F01 F02
F13 F14
RETURN NEXT
F15 F16
F27 F26
RETURNPREVIOUS
PREVIOUS
Window 4: FEATURE
M01 M02
M05
M03 M04
RETURN

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25C340
Below are the adjustments ranges and initial values for FIXVALUE category.
FIX VALUE
F01 OPTION 1 00-FF B3 B3
F02 OPTION 2 00-FF 07 07
F03 E-SAVE 00-3F 2A 2A
F04 TUNER SETUP 00, 01 00 00
F05 R-TONE RD 00-7F 03 03
F06 R-TONE BD 00-7F 7C 7C
F07 B-TONE RD 00-7F 00 00
F08 B-TONE BD 00-7F 04 04
F09 FM LEVEL 00-1F 16 16
F10 AFC GAIN 00, 01 00 00
F11 G DRIVE 00, 0F 0F 0F
F12 FBT BLK SW 00, 01 01 01
F13 V COMP 00-07 07 07
F14 OSD CONT 00-03 01 01
F15 SHARPNESS 00-3F 0D 0D
F16 FLT SYS 00-07 01 01
F17 KILLER OP 00-07 02 02
F18 PRE SHOOT 00-03 00 00
F19 CORING 00-03 04 04
F20 DC REST 00-03 02 02
F21 BS START 00-03 01 01
F22 BS GAIN 00-03 01 01
F23 ABL START 00-07 00 00
F24 R/B ANGLE 00-0F 08 08
F25 H BLK R 00-0F 03 03
F26 H BLK L 00-0F 00 00
F27 YC 00-07 05 04
SERVICE
POSITION ADJUST ITEM DATA
RANGE
INITIAL VALUE
(Hex)
Table - A
Below are the ranges and initial values for each adjustment and in each categories.
DEF
D01 H-PHASE 00-1F 0C
D02 V-SIZE 00-7F 40
D03 V-POSITION 00-3F 20
D04 CC-POSITION 00-FF 1A
D05 V-LINEARITY 00-1F 18 Must be "13"
D06 V-S-CORRECTION 00-1F 0C Must be "10"
SERVICE
POSITION ADJUST ITEM DATA
RANGE
INITIAL VALUE
ADJUSTMENT CONTENTS
Table - B

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25C340
IC2001
IC2102 X
IC3001 X
IC201
Data is stored in IC2102.
Adjust items related MTS only.
HoldingdownboththeVol-up/Ch-downbuttonsontheTVsetatservicemodeformore than2 secondswill automatically
write the above initial values into IC2102.
Table - E
The adjustment is needed to compensate for characteristics
of parts including IC201.
Holding down both theVol-up/Ch-down buttons on theTV set
intheservice mode formorethan2secondswillautomatically
write the above initial values into IC2102.
X
X
ADJUSTMENT
NECESSARY UNNECESSARY
PART REPLACED NOTES
SIGNAL
S01 RF AGC 00-3F 14
S02 VIDEO LEVEL 00-07 03
S03 Y-MUTE 00-03 00
"01":Y-MUTE, "02":V-STOP &Y-MUTE
"03":
Activate color killer circuit.
S04 SUB BIAS 00-FF 30 Must be "30"
S05 R-BIAS 00-FF 00
S06 G-BIAS 00-FF 00
S07 B-BIAS 00-7F 00
S08 R-DRIVE 00-7F 53
S09 B-DRIVE 00-7F 53
S10 CONTRAST 00-7F 5A
S11 TINT 00-7F 40
S12 COLOR 00-7F 40
S13 BRIGHTNESS 00-7F 40
S14 BRIGHTNESS 2 00-7F 40
SERVICE
POSITION ADJUST ITEM DATA
RANGE
INITIAL VALUE
ADJUSTMENT CONTENTS
Note: Refer to the SERVICE ADJUSTMENT for each corresponding values.
Table - C
M01 MS LEVEL 00-0F 0A
M02 MTS-VCO 00-3F 20
M03 FILTER 00-3F 1C
M04 LOW SEPARATION 00-3F 20
M05 HIGH SEPARATION 00-3F 1B
SERVICE
POSITION ADJUST ITEM DATA
RANGE
INITIAL VALUE
ADJUSTMENT CONTENTS
Table - D
FEATURE
Note: Refer to the SERVICE ADJUSTMENT for each corresponding values.
CRT XAdjust items related to picture tube only.

9
25C340
Figure B:WAVEFORM FOR SCREEN ADJUSTMENT
Ë
SERVICE ADJUSTMENT
Note: Before making the service adjustment, make the
bus data settings.
+B Adjustment
(1) For the chassis with the +B adjustment control
1. Receive a good local channel.
2.Select VIDEO ADJUSTMENT RESET on the
menu to get the video reset.
3. Connect a DC voltmeter between the +B line (at
SWtransformer) of R611andthe groundterminal.
4. Adjust R738 so that the voltmeter should read
128.65±0.35V.
(2) For the chassis without the +B adjustment
control
1. Receive a good local channel.
2.Select VIDEO ADJUSTMENT RESET on the
menu to get the video reset.
3. Connect a DC voltmeter between the +B line (at
SWtransformer) of R611andthe groundterminal.
4. Make sure that the voltmeter reads 128.65±0.35V.
Video Level (TV DetVideo Level)
Adjustment
1. Receive a good local channel.
2. Enter the service mode signal category and select
the service adjustment "S02".
3. Set the data value to "02" first, then adjust the data
to "04".(If out of spec, readjust the data in the range
of "00" to "07" to obtain a normal contrast level.)
RF AGC Adjustment
1. Receive a good local channel.
2. Enter the service mode signal category and select
the service adjustment "S01".
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:You have to exit the service mode first to
select another channel.
Screen Adjustment
1. Connect to oscilloscope probe between TP854 and
ground of the CRT unit.
2. Receive a good local channel.
3. Enter the service mode Signal category and set the
service adjustment "S04" to step 30.Then select the
service adjustment "S12" and set the data value to
"00"to setthecolor level totheminimumlevel.(record
the original data first).You may skip this step, if you
selected a B/W picture or monoscope pattern. Set
alsothe"S05/S06/S07"data to minimum level("00").
2.35Vdc
GND
4. Select the service adjustment "S03" and set the data
valueto"01" to turnofftheluminance signal (Y-mute).
5. Select the service adjustment "S14" and adjust the
data value to obtain 2.35 volts as shown in Figure B.
6. Adjust the master screen control until the raster
darkens to the point where raster is barely seen.
7. Adjusttheserviceadjustment"S05" red,"S06"green,
"S07" blue to obtain a good grey scale with normal
white at low brightness level.
8. Selecttheservicea adjustment "S03" and reset data
to"00".Select the serviceadjustment "S12"andreset
data to obtain normal color level.
9. Remove probe and reset the master screen control
to obtain normal brightness range.
White Balance Adjustment
1. Receive a good local channel.
2. Select the service adjustment "S12" and set the data
valueto "00" to set the color level to the minimun.You
may skip this step, if you selected a B/W picture or
monoscope.
3. Alternately adjust the service adjustment data of
"S08" and "S09" until a good grey scale with normal
white is obtained.
4. Select the service adjustment "S12" and reset data
to obtain normal color level.
Sub-Picture Adjustment
1. Receive a good local channel.
2. Make sure the customer picture control is set to
maximum.
3. Enter the service mode and select the service
adjustment "S10".
4. Adjust the data value to achieve normal contrast
range.
Sub-Tint Adjustment
1. Receive a good local channel.
2. Setthecustomer tint controltothe center ofit’srange.
3. Enter the service mode and select the service
adjustment "S11".
4. Adjust"S11"datavalueto obtain normalfresh tones.
Sub-Color Adjustment
1. Receive a good local channel.
2. Make sure the customer color control is set to center
position.
3. Enter the service mode and select the service
adjustment "S12".
4. Adjust "S12" data value to obtain normal color level.
Sub-Brightness Adjustment
1. Receive a good local channel.
2. Make sure the customer brightness control is set to
center position.
3. Enter the service mode and select the service
adjustment "S13".
4. Adjust "S13" data value to obtain normal brightness
level.

10
25C340
Ë
MTS ADJUSTMENT
MTS Level Adjustment
1.Feed the following monaural signal to pin (14) of
IC3001.
Monaural signal: 300Hz, 245mVrms
2. Connect the rms voltmeter to pin (39) of IC3001.
3.Enter the service mode and select the service
adjustment "M01".
4. Adjust the data so that the rms voltmeter reads 490
±10mVrms.
Separation Adjustment
1. Connect the rms voltmeter to pin (39) of IC3001.
2. Receive the following composite stereo signal 1.
Composite stereo signal: 30% modulation, left
channel only, noise reduction on, 300Hz
3.Enter the service mode and select the service
adjustment "M04".
4. Adjust the data until the AC voltage reading of the
rms voltmeter is minimum.
5. Receive the following composite stereo signal 2.
Stereo signal: 30% modulation, left channel only,
noise reduction on, 3kHz
6.Enter the service mode and select the service
adjustment "M05".
7. Adjust the data until the AC voltage reading of the
rms voltmeter is minimum.
8.Take the above steps 1 thru 7 again for fine
adjustment.
Vertical-Size,V-Linearity and
V-S Correction Adjustments
1. Receive a good local channel.
2. Enter the service mode DEF category and select the
adjustment "D02" for Vertical Size, "D05" for V-
Linearity and "D06" forV-S Correction Adjustment.
3. Set in order "D05" for V-Linearity, "D06" for V-S
Correction and set the data to get the best linearity.
4. Then adjust "D02" data until it become a proper
vertical size.
Horizontal Position Adjustment
1. Receive a good local channel.
2. Enter the service mode DEF category and select the
adjustment "D01".
3. Adjust "D01" data value to center the picture.
Vertical-Phase Adjustment
1. Receive a good local channel.
2. Enter the service mode DEF category and select the
adjustment "D03".
3. Adjust "D03" bus data to get the most acceptable
vertical position.
Note:The step range is 20 (32)+12 (3 steps)/
-20 (5 steps).
(Push once move 4 steps.)
Caption Position Adjustment (Horizontal)
1. Receive a good local channel.
2. Enter the service mode DEF category and select the
adjustment "D04".
3. Ablacktextboxwillappearon thescreen.(see Figure
C.below)
4. Adjust "D04" data value to balance the text box
position in the center. (A=B).
Figure C.
A B

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654321
A
B
C
D
E
F
G
H
25C340
CHASSIS LAYOUT
PWB-A
PWB-B

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654321
A
B
C
D
E
F
G
H
25C340
BLOCK DIAGRAM

13
25C340
DESCRIPTION OF SCHEMATIC DIAGRAM
NOTES:
1. The unit of resistance "ohm" is omitted.
(K=k Ω =1000 Ω , M=M Ω )
2. All resistors are 1/16 watt, unless otherwise noted.
3. All capacitors are µ F, unless otherwise noted.
(P=pF=µµF)
4. (G) indicates ±2% tolerance may be used.
5. indicates line isolated ground.
VOLTAGE MEASUREMENT CONDITIONS:
1. All DC voltages are measured with DVM connected
between points indicated and chassis ground, line
voltagesetat 120VACandall controls set for normal
picture unless otherwise indicated.
2. All voltages measured with 1000µ V B & W or Color
signal.
WAVEFORM MEASUREMENT CONDITIONS:
1. Photographs taken on a standard gated color bar
signal, the tint setting adjusted for proper color.The
wave shapes at the red, green and blue cathodes of
the picture tube depend on the tint, color level and
picture control.
2. indicates waveform check points (See chart,
waveforms are measured from point indicated to
chassis ground.)
å AND SHADED ( ) COMPONENTS
= SAFETY RELATED PARTS.
' MARK= X-RAY RELATED PARTS.
This circuit diagram is a standard one, printed circuits
may be subject to change for product improvement
without prior notice.
WAVE FORMS

87 109654321
A
B
C
D
E
F
G
H
SCHEMATIC DIAGRAM: MAIN-1 Unit
25C340
14

1716151413121110 18 19
25C340
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SCHEMA
TIC DIAGRAM: MAIN-1 Unit
25C340
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25C340
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SCHEMATIC DIAGRAM: CRT Unit
25C340
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25C340
PRINTEDWIRING BOARD ASSEMBLIES
PWB-B: CRT Unit (Wiring Side)

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25C340
PWB-A: MAIN Unit (Wiring Side)