Sharp VT-3418X User manual

N.S.W.
W-341 8X
VT-5118X
SERVICE MANUAL
VT-341 8X
S94D8VT3418Xi
i==T=D
TV/VCR COMBINATION
TELEVIDEO
Chassis No. VP- 7
VT-341 8X
VT-51 18X
MODELS VT-51 18X
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.
FEATURE
n Full Auto Search Tuning System
H High Speed Video Search System
n On Screen Digital Channel/Sound Level/
l PAUSECAM: 7 times
Tuning Display, Control (Contrast, Colour,
Brightness, Tint, P-Tone) Symbol and Level
H Blue Back Off Timer
n 40 Key, Wireless Remote Control Unit
n Channel Skip
H Dew Warning Indicator
W DPSS (Digital Program Search System)
l NTSC: 5 times(SP), 15 times (EP)
w Quick Start Playback with Full Loading System
n Still/Slow Function with Noiseless Frame Still
n Digital Automatic Tracking Control
n Automatic Playback Function
n AHC (Automatic Head Cleaning System)
I
CONTENTS
Page Page
.
SPECIFICATIONS
........................
2
l OVERALL SCHEMATIC DIAGRAM
........
65
l IMPORTANT SERVICE NOTES
.............
3
l CHASSIS LAYOUT OF TV SECTION
....... 69
l LOCATION OF USER’S CONTROL
......... 4
l BLOCK DIAGRAM OF TV SECTION
....... 73
. DISASSEMBLY AND REASSEMBLY
........ 7 . DESCRIPTION OF TV SECTION
. ADJUSTMENT OF THE SCHEMATIC DIAGRAM
....... .: ..... 82
TV ELECTRICAL CIRCUITRY
...........
8
. CHASSIS LAYOUT OF VCR SECTION
......
99
. FUNCTION OF MAJOR MECHANICAL PARTS
14
. BLOCK DIAGRAM OF VCR SECTION
..... 101
*
. ADJUSTMENT, REPLACEMENTAND
. DESCRIPTION OF VCR SECTION
ASSEMBLY OF MECHANICAL UNITS
..
16
SCHEMATIC DIAGRAM
............. 111
. ADJUSTMENT OF THE . PRINTED WIRING BOARD ASSEMBLIES . .
119
VCR ELECTRICAL CIRCUITRY
......... 41
. REPLACEMENT PARTS LIST
............ 129
. TROUBLESHOOTING
...................
47
. PACKING OFTHESET
.................
167
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 -
qualified service personnel.
serviceable parts inside. Refer servicing to
SHARP CORPORATION

SPECIFICATIONS
n OUTLINE OF THE PRODUCT
Power Source:
Power Consumption:
Receiving Broadcast Standard:
Receiving Channel:
Receiving System:
Antenna Input Impedance:
Video Signal:
Audio Signal:
Temperature:
Di mentions (Approx.):
Weight (Approx.):
Cabinet Material:
Accessories:
11 O-240 V AC, 50/60 Hz
VT-3418X: 77 w
i/T-5118X: 98 W
PAL System B/G, I, D/K, M
VHF;
lA-S20
UHF;
E21-US83
Sound;
Colour;
VHF/UHF;
Input;
output;
Input;
output;
5.5/6.0/6.5/4.5 MHz
PAL / SECAM / NTSC
75 ohm Unbalanced (DIN)
O-5-2.0 Vp-p / 75 ohm (RCA)
1 .O Vp-p / 75 ohm (RCA)
- 8 d b / 47k ohm (RCA)
-8db/lkohm(RCA)
Operation; 5”Cto40”C
Strege;
- 20°C to 60°C
VT-3418X: 392 mm (W) x 371 mm (H) x 395 mm (D)
VT-5118X: 523mm(W)x488mm (H)x483 mm (D)
VT-3418X: 14.2 kg
VT-5118X: 26.1 kg
Plastic
0 Operation Manual
Cl Infrared Remote Control Unit
0 Dry Batteries, Type AA (x 2 PCS)
0 Guarantee Card
n TV SECTION
Viewing Area:
Picture Power:
Speaker Output:
Picture Tube:
n VCR SECTION
VT-3418X: 33.54 cm Diagonal Measurement
VT-51 18X: 50.8 cm Diagonal Measurement
VT-3418X: 22.0 kV at 800 ,& Beam Current
VT-5118X: 25.0 kV at 1100 fi Beam Current
VT-3418X: 1.5 W at Max. (8 cm Round Dynamic x 2 PCS)
VT-51 18X: 1.5 W at Max. (8 cm Round Dynamic x 2 PCS)
Type;
VT-3418X: VB370BVBKl U-S (Tint Tube)
VT-5118X: VB51JFCGlX/E2 (TintTube)
Heater; VT-3418X: 6.3 V, 300 mA
VT-5118X: 6.3 V, 680 mA
Focus;
High Bi-Potential Electrolstatic
Outline: VHS Video System Colour Video Cassette Recorder
Format: VHS PAUNTSC Standard
Video Recording System :
Rotary Slant Azimuth 2-Head Helical Scan System
Luminance: FM Recording
Chrominance: Low Frequency Converted Direct Recording
Video Signal System: PAUSECAM/NTSC 3.58 MHz 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), 11.68 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.

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 10 k 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-3418X: When repairing the circuit, be sure not toincrease the high voltage to more
than 25.3 kV, (at beam 0 +) for the set.
VT-5118X: When repairing the circuit, be sure not to increase the high voltage to more
than 29.3 kV, (at beam 0 +) for the set.
2. VT-3418X: 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 ,&) in the case of the set. The set has
been factory
-Adjusted to the above-mentioned high voltage.
VT-5118X: To keep the set in a normal operation, be sure to make it function on
25.0 kV + 1.5 kV (at beam 1100 ,uA) 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. DOnot 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-
capacity networks, mechanical insulators etc.

LOCATION OF USER’S CONTROL
\ STOP/EJECT BUlTON
PLAY BlJlTON
FF (Forward video search)
BUTTON
mh ;;;rF$verse video search)
VlDEO INPUT JACK
I
AUDIO INPUT JACK
I r
VOLUME UP/DOWN BlJlTONS
CHANNEL UP/DOWN BUlTONS
CONTROL PANEL
INSIDE THE COVER
VIDEO AUDIO
POWER BUTTON
I
SENSOR AREA FOR
REMOTE CONTROL
VT-341 8X
o I
I p
q
I o
v
. . .
JL
POWER CORD
MAIN POWER SWITCH (0 I)
ANTENNA IN TERMINAL
_1
AUDIO OUT TERMINAL -
VIDE; OUT TERMINAL
VT-51 18X .
P;;WER CORD
MAIN POWER SWITCH (0 I)
ANTENNA IN TERMINAL -
I
AUDIO OUT TERMINAL -
VIDEO OUT TERMINAL
4

Remote Control Battery Installation
The remote control lets you operate this product at a distance. Just aim the front of the remote
control at the photoreceptor window situated on the front panel and press the appropriate
buttons.
Inserting the Batteries
Battery
cover
The remote control operates on two R6 (UM/SUM-3,
AA) 1.5 volt batteries (included). If the remote control
does not operate or fails to function normally due to
weak batteries, new batteries can be purchased at
electronics or camera stores.
0
Open the battery cover. (Remove any old bat-
teries that may be in the remote control.)
@
Insert new batteries and match their polarities
( + and -) with the markings inside the compart-
ment.
@ Replace the cover.
Location of Controls
POWER ON/OFF button (0 I)
EJECT/LOAD button
I
SHARP
VIDEO -TV
C-COCK
r
CHANNEL SELECT
buttons
666
--686
I
DISPLAY button
DPSS(O, @)I
SLOW@, 0) buttons
SP/LP*EP button -
REC button
REW/Reverse -
Video Search button
TIMER ON/OFF button
CONFIRMING TIMER -
PROGRAMME button
/-- MUTE button
CHILD-LOCK button
r CHANNEL UP/DOWN&&tons
(TRACKING buttons)
VOLUME ADJUSTMENT
1 buttons
r SLOW PLAYBACK button
r COUNTER RESET button
STOP button
- F*ADV button
- PAUSE/STILL button
FF/Forward
Video Search button
PLAY button
-, + buttons
PROGRAMME button
MENU button
SET button
5

VT-341 8X
VT-5118X
c
DISASSEMBLY AND REASSEMBLY
n TV SECTION
I. VT-3418X: Remove the eight screws off the rear cover.
VT-51 18X: Remove the nine screws off the rear cover.
2.
Disconnect the F and G connectors from the main PWB.
3. Remove the screws off the video unit and take out the unit.
4. Remove the two screws from the main PWB and separate the PWB from the video unit
VT-341 8X
rr
VT-51 18X
6

n CONNECTIONS FOR SERVICING
Use the following extension cables in servicing the VCR unit taken out of the set.
Extension cables:
Part codes QCNW-3778CEZZ, QCNW-3780CEZZ
l Connecting the extension cables
(1) Between AB (TV unit) and JA (AV jack):
Connect the cable QCNW-3778CEZZ between the AB plug and the AB socket.
(2) Between AL (TV unit) and LA (LED unit):
Connect the cable QCNW-3780CEZZ between the AL plug and the AL socket.
Extension cable: QCNW-3780CEZZ
Extension cable: QCNW-3778CEZZ
5. Remove the CRT PWB, degaussing coil connector G, and front power switch remote control PWB. Place
the main PWB upright.
6. Reconnect the CRT PWB. Put the main PWB and the VCR unit together as shown below. Keep the front
power switch remote control PWB, speakers and degaussing coil connector G off position.
Only for
~oUnd0
* VT-51 18X
,
\ ‘LINE FILTER PWB
(Only for VT-341 8X)
/
Power SW+I/C PWB
DA

VT-341 8X I
VT-5118X
I
ADJUSTMENT OFTHE
TV ELECTRICAL CIRCUITRY
VIDEOKHROMA ADJUSTMENT
I
Adjusting Conditions Adjusting Procedures
1. CRT Cut-off Adjustment
Adjusting Point
Cl R853: Red Bias control
Cl R859: Green Bias control
Cl R865: Blue Bias control
El T602: Screen control (a pat-t of T602)
Cl R857: Green Drive control
!Il R863: Blue Drive control
Note:
Prior to this adjustment, warm up the unit with the
beam current of more than 6OOfl (VT-3418X) I
7004 (VT-51 18X) for more than 30 minutes.
1. Receive “MONOSCOPE PATTERN” signal with
pattern generator.
2. Set Red bias control at MIN (O/l 0) position.
Set Green bias control at MIN (O/l 0) position.
Set Blue bias control at MIN (O/l 0) position.
Set Green drive control at CENTER (5/l 0) position.
Set Blue drive control at CENTER (5/l 0) position.
3. Set the control at the “NORMAL” position that
Contrast is MAX (60), Colour is CENTER (0) an
Brightness is CENTER (0) using control, “A” and
“v” keys.
4. Set the Screen control at MIN (O/l 0) position.
5. Turn on 51401 (Service switch) at the horizontal
line position.
6. Connect the oscilloscope to TP852 (Red Cathode).
2. Sub-Contrast Adjustment
I
Adjusting Point
I
0 R421: Sub-Contrast control
Note:
Prior to this adjustment, warm up the unit with the
beam current of more than 600@ (VT-3418X) I
7004 (W-51 18X) for more than 30 minutes.
1. Receive “MONOSCOPE PATTERN” signal with
pattern generator.
2. Set the Contrast and Brightness controls at MAX
position.
3. Connect DC milliammeter to TP6019 and
TP602@.
(Full scale: 3 mA)
1. Adjust the Sub-Brightness control (R425) so that
the blanking pulse on oscilloscope is 10 + lVp-p.
2. Slowly turn the Screen control clockwise and stop
it where the horizontal raster appears slightly, in
one of the three colours.
3. Carefully adjust the Bias controls of the other two
colours untii the horizontal raster becomes white.
4. Turn the Screen control counterclockwise until
the horizontal raster disappears, and stop it.
1. Adjust Sub-Contrast control so that the beam
current becomes 0.8 mA (VT-3418X) / 1 .l mA (VT-
5118X).
8

VT-341 8X
W-5118X
VIDEOICHROMA ADJUSTMENT (Continued)
3. White Balance and Back Ground Adjustment
Adjusting Point
El R857: Green Drive control
Cl R863:
Blue Drive control
Cl R421: Sub-Contrast control
Vote:
srior to this adjustment, warm up the unit with the
5eam current of more than 6004 (VT-3418X) I
7004 (VT-51 18X) for more than 30 minutes.
I. Receive “MONOSCOPE PATTERN” signal with
pattern generator.
!. Set the Contrast and Brightness controls at MAX
position.
5. Connect beam ammeter to TP601 and TP602.
(Full scale: 3 mA)
4. Sub-Tint Adjustment
1
j. Bell Filter Adjustment
Adjusting Point
0 R1882: Sub-Tint control
1. Feed “NTSC COLOUR BAR” signal to video in jack
with colour bar generator at the AV mode.
2. Connect oscilloscope to TP853 (B - Y).
3. Set the Tint control at the CENTER (0) position.
4. Set Service switch 51401 at the Video Cut position
to cut off the Y-signal.
Adjusting Point
0 T1802: Bell Filter
1. Receive “SECAM COLOUR BAR” signal with colour
bar generator.
2. Connect oscilloscope to TP1801 with the
following settings.
l Range:
0.05V / div. AC
l Sweep Time: 20psec
/ div.
l Probe:
l/l 0 (3OpF, 1 OMQ or more)
1. Adjust the Sub-Contrast control so that the beam
current becomes 0.8 mA (VT-3418X) / 1 .l mA (VT-
5118X) (rough adjustment).
2. Adjust the Green Drive control and Blue Drive
control so that the colour temperature is at
10900K.
l High beam:
0.8 mA (VT-341 8X)
1.1 mA(VT-5118X)
3. Adjust the Contrast control and Brightness
control so that the beam current is approx.
200,&, and check that the colour temperature is
at 9300°K. If the temperature is not at 9300”K,
go back to “CRT CUT-OFF ADJUSTMENT” and
repeat the adjustment.
(X = 0.285, Y = 0.292)
1. Adjust Colour control key to obtain the output of
approx. 3Vp-p.
2. Adjust Sub-Tint control (R1882) so that the output
waveform is as shown in figure below.
3. Return 51401 to CENTER (normal position).
Same
B-Y
//-
level y _.z_‘-
-
/@(
/’
/-
.)
.
-
-
W Y Cy GMg R B
-
1. Adjust the Bell Filter (T1802) so that the red (R)
output and blue (B) output will have the same
amplitude.
CY G Mg R B
‘c_ Same amplitude r-
9

VIDEOICHROMA ADJUSTMENT (Continued)
Adjusting Conditions
I
Adjusting Procedures
6. PAL Chroma Adjustment
Adjusting Point
1. Adjust the Colour control key so that the output
Cl R1806: 1 H Delay Amp. control
waveform of colour difference signal becomes
0 T1801: 1 H Delay Phase control
1.5 vp-p.
Note: Before this adjustment, the PIFIAFTIAGC
adjustment must have been completed.
1. Receive “PAL COLOUR BAR” signal with pattern
generator.
2. Connect the following resistance matrix to pins 3
and 4 of the connector (K), to which an
oscilloscope is connected.
22 kSZ
To oscilloscope
TP853 (K)+
Resistance Matrix
3. Set the Service switch 51401 at the Video Cut
position to cut off the Y-signal.
7. SECAM Killer Adjustment
rAdjusting Point
0 11803: SECAM
Killer control
1. Receive”SECAM COLOUR BAR” signal with colour
bar generator.
2. Connect oscilloscope to TP1802 with the
,lY.)
following settings.
l Renge:
lV/div. DC
(Adjust vertical position proper
l Sweep Time: 20psec / div.
2. Adjust R1806 and T1801 so that the output
waveform shown in Fig. a is corrected to that
shown in Fig. 6.
3. Return 51401 to CENTER (normal position).
W Y Cy G Mg R B
--#--.
-
r
-
-
u
--*m---w
1
.- ---m-
1
1.5 vp-p
I
mm --m-w
Figure a. Waveform before the adjustment
Figure 6. Waveform after the adjustment
1. Adjust T1803 to obtain maximum DC voltage at
TPl802 (approx. 9.5V).
IO