Sharp VT-G14 User manual

1
VT-G14
VT-G21
VIDEO TV
RATING 110-240V(AUTO.) ~ 50/60 Hz
POWER CONSUMPTION 112 W
SERIAL NO. Jxxxxxxxxx
SHARP CORPORATION
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.
SHARP CORPORATION
TV/VCR COMBINATION
TELEVIDEO
Chassis No. VP-7
MODELS
WARNING
The chassis in this receiver is partially hot. Use an isolation transformer between the line cord plug and power receptacle,
when servicing this chassis.
To prevent electric shock, do not remove cover.
No user — serviceable parts inside. Refer servicing to qualified service personnel.
VT-G14
VT-G21
SERVICE MANUAL
S11N9VT-G14//
ËFull Auto Search Tuning System
ËOn Screen Digital Channel/Sound Level/Tuning Display,
Control (Contrast, Colour, Brightness, Tint, Sharpness,
White temp) Symbol and Level
ËBlue Back Off Timer
Ë39 Key, Wireless Remote Control Unit
ËChannel Skip
ËHigh Speed and Double Speed Video Search System
»PAL/MESECAM : 3 times/7 times (SP/LP)
»NTSC : 3 times/5 times (SP/LP)
5 times/15 times (EP)
VT-G14 VT-G21
FEATURE
ËDPSS (Digital Program Search System)
ËQuick Start Playback with Full Loading System
ËDigital Automatic Tracking Control
ËAutomatic Playback Function
ËAHC (Automatic Head Cleaning System)
ËSharp Super Picture
Ë345 Times Hi-Speed FF/REW
MODEL VT-G21
CAUTION : DANGEROUS
VOLTAGE INSIDE
TO PREVENT ELECTRIC SHOCK, DO NOT
REMOVE COVER. NO USER-SERVICEABLE
PARTS INSIDE. REFER SERVICING TO
QUALIFIED SERVICE PERSONNEL.
Example of suffix symbol:
The component parts of this model are partially
differentdependingon theirsuffix symbols.Before
servicing the units, be sure to check the suffix
symbol on the model label that is applied on the
back of the unit.
Suffix "J" for Russia

2
VT-G14
VT-G21
CONTENTS
»SPECIFICATIONS......................................................... 3
»IMPORTANT SERVICE NOTES.................................... 4
»LOCATION OF USER'S CONTROL.............................. 5
»DISASSEMBLY AND REASSEMBLY ............................ 7
»ADJUSTMENT OF THE TV ELECTRICAL
CIRCUITRY ................................................................. 10
»PRECAUTIONS IN REASSEMBLING......................... 24
»FUNCTION OF MAJOR MECHANICAL PARTS ......... 25
»ADJUSTMENT, REPLACEMENTAND
ASSEMBLY OF MECHANICAL UNITS ....................... 27
»ADJUSTMENT OF THE VCR ELECTRICAL
CIRCUITRY ................................................................. 46
»TROUBLESHOOTING ................................................ 48
»CHASSIS LAYOUT...................................................... 68
»BLOCK DIAGRAM OF TV SECTION .......................... 70
»DESCRIPTION OF TV SECTION
SCHEMATIC DIAGRAM .............................................. 74
»SOLID STATE DEVICE BASE DIAGRAM ................... 75
»WAVEFORMS ............................................................. 76
»BLOCK DIAGRAM OF VCR SECTION ....................... 90
»DESCRIPTION OF VCR SECTION
SCHEMATIC DIAGRAM .............................................. 99
»PRINTED WIRING BOARD ASSEMBLIES ............... 106
»REPLACEMENT PARTS LIST ...................................114
»PACKING OF THE SET ............................................ 134
Page Page

3
VT-G14
VT-G21
SPECIFICATIONS
ËOUTLINE OF THE PRODUCT
Power Source: 110~240 V AC, 50/60 Hz
Power Consumption: VT-G14 : 94 W
VT-G21 : 112W
Receiving Broadcast Standard: B/G, I, D/K, M
Receiving Channel: VHF; 1A~S36
UHF; S37~C57
Receiving System: Sound; 5.5/6.0/6.5/4.5 MHz
Colour; PAL/SECAM/NTSC
Antenna Input Impedance: VHF/UHF;75 ohm Unbalanced (DIN)
Video Signal: Input; 0.5~2.0 Vp-p/75 ohm (RCA)
Output; 1.0 Vp-p/75 ohm (RCA)
Audio Signal: Input; 0.5 Vrms/10k ohm (RCA)
Output; 0.5 Vrms/1k ohm (RCA) (54% MOD)
Temperature: Operation; 5°C to 40°C
Storage; -10°C to 60°C
Dimensions (Approx.): VT-G14 : 378 mm (W) ×387 mm (H) ×384 mm (D)
VT-G21 : 505 mm (W) ×503 mm (H) ×478 mm (D)
Weight (Approx.): VT-G14 : 12.7 kg
VT-G21 : 23.5 kg
Cabinet Material: Plastic
Accessories: Operation Manual
Infrared Remote Control Unit
Dry Batteries, Type AA (×2 pcs.)
ËTV SECTION
Viewing Area: VT-G14 : 33.54 cm Diagonal Measurement
VT-G21 : 50.8 cm Diagonal Measurement
Picture Power: VT-G14 : 22.0 kV at 800 µA Beam Current
VT-G21 : 25.0 kV at 1100 µA Beam Current
Speaker Output: VT-G14 : 3.0 W at Max. (5×9 cm oval type ×1pc.)
VT-G21 : 3.0 W at Max. (5×9 cm oval type ×2pcs.)
Picture Tube: Type; VT-G14 : VB370BVBK1S-S (Tint Tube)
VT-G21 : VB540ADAC1S*S (Tint Tube)
Heater; VT-G14 : 6.3 V, 300 mA
VT-G21 : 6.3 V, 600 mA
Focus; High Bi-Potential Electrostatic
ËVCR SECTION
Outline: VHS Video System Colour Video Cassette Recorder
Format: VHS PAL/NTSC Standard
Video Recording System: Rotary Slant Azimuth 2-Head Helical Scan System
Luminance: FM Recording
Chrominance: Low Frequency Converted Direct Recording
Video Signal System: PAL/SECAM(MESECAM Rec)/NTSC 3.58MHz Colour
Cassette Tape: VHS Type Video Cassette Tape
Tape Width: 12.7 mm
Tape Speed: PAL ; 23.39 mm/s (SP), 11.70 mm/s (LP)
NTSC ; 33.35 mm/s (SP), 16.68 mm/s (LP·PB only), 11.12 mm/s (EP)
Recording/Playback Time: SP ; Max. 240 min (with E-240)
LP ; Max. 480 min (with E-240, PAL only)
EP ; Max. 480 min (with T-160, NTSC only)
Note: The antenna must correspond to the new standard DIN 45325 (IEC 169-2) for combined UHF antenna with
75 ohm connector.
Specifications are subject to change without prior notice.

4
VT-G14
VT-G21
IMPORTANT SERVICE NOTES
Maintenance and repair of this receiver should be done by qualified service
personnel only.
SERVICING OF HIGH VOLTAGE SYSTEM AND
PICTURE TUBE
When servicing the high voltage system, remove static charge from it by
connecting a 10k ohm Resistor in series with an insulated wire (such as a
test probe) between picture tube dag and 2nd anode lead. (AC line cord should
be disconnected from AC outlet.)
1. 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 completely.
X-RAY
This receiver is designed so that any X-Ray radiation is kept to an absolute
minimum. Since certain malfunctions or servicing may produce potentially
hazardous radiation with prolonged exposure at close range, the following
precautions should be observed:
1. VT-G14: When repairing the circuit, be sure not to increase the high voltage to more
than 25.3 kV, (at beam 0 µA) for the set.
VT-G21: When repairing the circuit, be sure not to increase the high voltage to more
than 29.3 kV, (at beam 0 µA) for the set.
2. VT-G14: To keep the set in a normal operation, be sure to make it function on 22.0 kV +
1.5 kV – 2.0 kV (at beam 800 µA) in the case of the set. The set has been factory
– Adjusted to the above-mentioned high voltage.
VT-G21: To keep the set in a normal operation, be sure to make it function on 25.0 kV ±
1.5 kV (at beam 1100 µA) in the case of the set. The set has been factory –
Adjusted to the above-mentioned high voltage.
∴ If there is a possibility that the high voltage fluctuates as a result of the repairs, never
forget to check for such high voltage after the work.
3. Do not substitute a picture tube with unauthorized types and/or brands which may cause
excess X-ray radiation.
BEFORE RETURNING THE RECEIVER
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 fishpapers,
cabinet backs, adjustment and compartment covers or shields, isolation resistor-capac-
ity networks, mechanical insulators etc.

5
VT-G14
VT-G21
LOCATION OF USER'S CONTROL
Front
AV-1
IN
OUT
VIDEO AUDIO
AV-1
IN
OUT
VIDEO AUDIO
Thisservice manualis forVT-G14 andVT-G21.The
illustration of VT-G21 are used in this service
manual.
Rear
VIDEO
OUTPUT ANTENNA IN
terminal
AUDIO
INPUT
AUDIO
OUTPUT
VIDEO
INPUT
HEADPHONE jack
(Speaker audio turns off when connected
to a pair of headphones)
POWER button
VIDEO/AUDIO INPUT terminals
STOP/EJECT button
FF (Forward Video
Search) button
PLAY button
REW (Reverse Video
Search) button
PRESET button
CHANNEL UP/DOWN buttons
VOLUME UP/DOWN buttons
SHARP SUPER PICTURE button (This function will create a clearer image during playback.)
REC (Recording) button
REC indicator
PROGRAM TIMER indicator
CHILD-LOCK indicator
POWER/WAKE-UP TIMER indicator
Infrared sensor
window
STANDBY/ON
button

6
VT-G14
VT-G21
LOCATION OF USER'S CONTROL (Continued)
TV/VIDEO
CH
PLAY
STOP
REW
REC PAUSE
DPSS
PROG
MENU
TV
•
VCR COMBINATION
SET RETURNCONFIRM
FF
TR
123
456
78
0
9
COUNTER
RESET TAPE SPEED
TIMER
ON/OFF
RETURN button
CONFIRM button
• Used to confirm the
programme setting.
REW button
• Used to rewind the tape or to
conduct Reverse Video Search
during playback mode.
Remote Control
REC button
• Used to record a programme.
STANDBY/ON button
CHANNEL SELECT buttons
FLASHBACK button
Returns to previously
viewed channel.
TAPE SPEED button
• Used to select the recording
tape speed.
PLAY button
• Used for tape playback.
• Used to cancel the PAUSE/
STILL mode and return to nor-
mal playback operation.
SET button
TV/VIDEO Select button
Infrared Transmitter Window
MUTE button
Press →Mutes sound.
Press again →Restores
sound to previous level.
VOLUME UP/DOWN buttons
CHANNEL UP/DOWN
buttons (TRACKING ±/—)
• Used to select the
CHANNEL.
• Used to adjust the TRACK-
ING while playing the tape.
COUNTER RESET button
• Used to reset the tape
counter.
CHILD-PROOF LOCK button
• Used to lock any selected
mode.
FF button
• Usedtofast forwardthetape
ortoconductForwardVideo
Search during playback
mode.
STOP button
• Used to stop the tape.
PAUSE button
• Used to temporarily stop the
tapeduringrecordingmode.
• Used to display a still
picture during playback
mode.
DPSS buttons
• Press the ( /) button to
search for the index signal
and begin playback auto-
matically.
PROGRAMME button
• Press the button to set the
programme Timer.
MENU button
• Used to select the menu
screen.
Inserting batteries
Pull up
±, —buttons
TIMER ON/OFF button
Installing dry batteries in the remote control unit
Before using the TV set for the first time, install the supplied dry batteries in the remote control.
!With your thumb nail, pull up the slit as indicated by the arrow
to remove the back cover.
@Insert two batteries (size “AA”). Be sure to match the battery
±/—terminals with the ±/—marks inside the compartment.
#Replace the battery cover.
• Remove batteries if weak or if the unit is not in use for long periods.
• Do not mix old and new batteries.
• Incorrect installation of the batteries may damage the remote control.
DISPLAY button
• Usedtodisplaythedifferent
current settings on the
screen.

7
VT-G14
VT-G21
DISASSEMBLY AND REASSEMBLY
1. Remove the 10 rear cover fixing screws and detach the rear cover.
2. Take out the anode cap, CRT PWB, connectors F, G and AO, coating ground, SP chip, fixing screws and others.
3. Remove the 2(VT-G14)/1(VT-G21) Main PWB fixing screws and take out the Main PWB unit and the Power PWB.
4. Remove the 4 Power PWB fixing screws, and take out the Power PWB unit.
G
3
F
AO
2
(VT-G14 only)
4
1
1
VT-G21
VT-G14

8
VT-G14
VT-G21
DISASSEMBLY AND REASSEMBLY (Continued)
5. Remove the 7 VCR fixing screws, and detach the shielding case.
6. Remove the 4 cassette housing control fixing screws, and detach the cassette housing control.
7. Remove the 4 mechanism chassis fixing screws, and detach the mechanism chassis from the Main PWB.
8. Remove the 3 Main PWB fixing screws, and detach the Main PWB.
9. Remove the 4 Tuner/Def and IF PWB fixing screws, and detach the Tuner/Def and IF PWB.
5
6
7
7
7
8
9

9
VT-G14
VT-G21
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.
70~80°
Note: Fit the VCR unit the front cabinet with the front flap door tilted at 70~80°.
K
FRONT
F
G
B
B
AJ AJ AV
AM
AN
PA
PA
PB
PB
SP
AN
AM
AV
H
AO
AO
K
H

10
VT-G14
VT-G21
ADJUSTMENT OF THE TV ELECTRICAL CIRCUITRY
ADJUSTMENT PRECAUTIONS
1. Calling the service mode
Get the service test points (TP1002 and TP1003) of the set short-circuited.
2. Getting out of the service mode
Get the above service test points open.
3. On-screen display in the service mode
A service mode item and its data appear in two lines
at the lower left on the screen.
Top line : Service mode item (See below)
Bottom line : Data (See below)
Service mode
Item Display Data Variable range
DIRECT MODE DIRCT Adjustable in the DIRECT MODE
V-AMPLITUDE V-AMP 0 ~ 127 R CUT OFF (0 ~ 255)
V-LINEARITY V-LIN 0 ~ 31 G CUT OFF (0 ~ 255)
V-OUT PHASE V-POS 0 ~ 7 B CUT OFF (0 ~ 255)
H-POSITION H-POS 0 ~ 31 G DRIVE GAIN (0 ~ 255)
BELL FILTER BELL 0 ~ 3 B DRIVE GAIN (0 ~ 255)
R-Y BLACK OFFSET R-Y 0 ~ 15
B-Y BLACK OFFSET B-Y 0 ~ 15
Y-SUB CONTRAST CONT 0 ~ 31
SUB COLOUR COLOR 0 ~ 240
SUB BRIGHT BRI 0 ~ 150
SUB TINT TINT 0 ~ 37
`NICAM D/K N-D/K 0 ~ 1
`IF INT/EXT IF-IN 0 ~ 1
`AGC GAIN AGCGA 0 ~ 31
`AGC OFF AGCOF 0 ~ 1
`FM SOUND ID FMID 0 ~ 3
`AUTO MUTE AMUTE 0 ~ 1
`NICAM LOW ERROR LIMIT NERRL 0 ~ 255
`NICAM UP ERROR LIMIT NERRU 0 ~ 255
`NICAM OUT LEVEL B/G B/G 0 ~ 31
`NICAM OUT LEVEL I I 0 ~ 31
`NICAM OUT LEVEL D/K D/K 0 ~ 31
`NICAM OUT LEVEL M M 0 ~ 31
`FM OUTPUT LEVEL FM 0 ~ 31
Note :
1) Item selectable by the CH '" buttons and data by the VOL '" buttons (effective on both
the remote controller and the set)
2) `This item is not used with the VT-G14 and VT-G21 (but displayed on the screen).