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

VIDEOKHROMA ADJUSTMENT (Continued)
Adjusting Conditions Adjusting Procedures
8. R -Y/B -Y Discriminator Adjustment
Adjusting Point
0 T1804: R
- Y Discriminator
0 T1805: B
- Y Discriminator
1. Receive “SECAM COLOUR BAR” signal with colour
bar generator.
2. Connect the oscilloscope (with two channecls) to
TP851 (R - Y) and the TP853 (B - Y), both located
on the CRT Socket Unit of the set.
l Renge: lV/div. DC
l Sweep Time: 20psec
/ div.
3. Set service switch 51401 at the Video Cut position
’ to cut-off the Y-signal.
4. Set both the Contrast and Brightness controls to
their maximum postions.
1. Adjust T1804 (R - Y) and T1805 (B - Y) so that DC
output level with colour control set at minimum
will be the same as that with colour control set at
100% of saturation. (A = B)
* Connect capacitor (0.001 ,xF) to TP851 and
TP853, thus to prevent noise interference.
2. Set service switch 51401 to the canter position.
TP851
TP853
*
B
DC OV
Same
DC output level
11

VT-341 8X
VT-5118X
DEFLECTION LOOP ADJUSTMENT
Adjusting Conditions
Adjusting Procedures
1. Focus Adjustment
l During the adjustment, keep the unit facing the east.
Adjusting Point
0 T602: Focuscontrol (a part of T602)
1. Receive “MONOSCOPE PATTERN” signal.
2 Set the Brightness and Contrast controls at
NORMAL position.
1. Adjust Focus control (a part of T602) to have best
focus at the central area of CRT.
Adjust point
2. Horizontal Center Adjustment
l During the adjustment, keep the unit facing the east.
1. Adjust R1602 so that the horizontal center of
picture is at the position which gives the relation
Adjusting Point
Cl RI 602: Horizontal Center control
Note: This adjustment should be performed after
ofA=B.
the purity and convergence adjustments.
I
1. Receive “MONOSCOPE PATTERN” signal.
+
A-
l
-)B
(+=
4
I
I
3. Vertical Linearity Adjustment
l During the adjustment, keep the unit facing the east.
Adjusting Point
Cl R526: Vertical Linearity control
1. Receive “MONOSCOPE PATTERN” signal.
1. Adjust R526 so that the vertical linearity of
picture is at best point.
4. Vertical Size Adjustment
l During the adjustment, keep the unit facing the east.
Adjusting Point
Cl R503: Vertical Size control
1. Adjust R503 so that the vertical size of picture is at
the same size as horizontal size.
1. Receive “MONOSCOPE PATTERN” signal.
2. Set the Brightness and Contrast controls at MAX
position.
. V-SIZE
8% TYP
12% MAX
12

VT-341 8X
VT-5118X
DEFLECTION LOOP ADJUSTMENT (Continued)
Adjusting Conditions
Adjusting Procedures
5. Vertical Centering Adjustment
l During the’adjustment, keep the unit facing the east.
Vertical Center Adjust switch
This adjustment should be performed after
the purity and convergence adjustments.
“MONOSCOPE PATTERN” signal.
1. Adjust 5501 so that the picture’s vertical center is
idential to CRT geometrical vertical center.
ADJUSTMENT OF THE IF CIRCUIT
Adjustment of the RF AGC
Adjustment of the AFT
Test point
TP201 @I (GND)
TP201 0 (Video Output)
Adjusting point
I
VROOl (AGC control) I
1. Receive the colour bar signal (input field
strength: 80 dBp).
2. Observe the video output terminal waveform
on the oscilloscope. Adjust VROOl (AGC control)
in the IF pack until the noise disappears from
the oscilloscope screen and the waveform
nearly comes into sync.
Just before shrinking
Figure 1.
Measuring Oscilloscope
instrument Signal generator
Mode
I
EE
Input signal
PIF frequency uniwave
Colour bar signal (70 dBp)
Test point
I
TP201 @ (GND)
TP201 @ (Video Output)
Adjusting point
I
TOO2 (AFT coil)
Specification -
I
1. Receive the colour bar signal (input field
strength: 70 dBp).
2. Using the signal generator, feed the PIF
frequency (38.9 MHz) signal (sinewave) to the
tuner IF output terminal.
3. Set the tuning switch to the VHF or UHF
position. Keep the tuning button (+) or (-)
depressed until the beating on the oscilloscope
screen be minimum.
4. Set the tuning switch on the normal position.
Adjust TOO2 (AFT coil) so that beating on the
oscilloscope screen be minimum.
I
Figure 2. IF Pack
13

Take-up pole
FUNCTION OF MAJOR
MECHANICAL PARTS (TOPVIEW)
0
24 AHC(Automatic Head Cleaner) Ass’y
Drum ass’y
Full erase head ass’y
I
Supply pole base ass’y
Tension arm ass’y
base ass’y 2 I
Q, \ @/Cheadass’y @Camztch
AJ
23 Dew sensor
Brake shifter w /
Loading motor
Master cam
Pinch roller lever ass’y
Relay shifter lever
Capstan D. D. motor
Reverse guide
h Take-up reel disk
Video
lever search brake
Back tension lever
Main supply brake
No.
Function
No.
Function
1.
3.
Full erase head ass’y
Erase the whole records on the tape in the recording
mode.
Tension arm ass’y
Detects the tension of tape while running, and brakes
the supply reel disk via the tension band.
13.
Reverse guide
Pulls out the tape in the video search rewind mode,
and controls the tape drive train height with the upper
and lower guides.
T5.
Relay shifter lever
Transmits the operation of the master cam to the
brake shifter, and operates the reverse guide.
4.
Brake shifter
,Set the position of brake or the like in accordance with
16.
Pinch roller lever ass’y
Press-fits the tape to the capstan during tape running.
the modes such as stop and playback. The right protrusion switches the clutch of the cassette
housing control assembly in “tape eject”, and makes
5.
Back tension lever the mechanism eject the tape.
Brakes the supply reel disk to a certain degree to .
’ prevent tape slackening during “half-loading”,
17.
Master cam
“loading” and “shifting from playback to video search Turns clockwise during loading, and counterclockwise
rewind”. during unloading, and moves the shifter or the like in
accordance with each mode.
7.
Main supply brake lever
Brakes the supply reel disk to prevent tape slackening
18.
Loading motor
when the unit is stopped in fast forward or rewind A motive power which drives the mechanism. It
transmits the power to the master cam and cassette
mode. housing control assembly via the belt.
9.
Main take-up brake lever
19.
Cam switch
Brakes the take-up reel disk to prevent tape slackening Rotates synchronously with the master cam, and
when the unit is stopped in fast forward or rewind detects the position of each mode by means of the
mode. internal switch.
11.
Video search brake lever
23.
Dew sensor
It is in contact with the take-up reel disk normally, and An element which detects condensation inside the
brakes it to a certain degree. It applies larger brake in unit. This element is activated, when it senses
the video search rewind mode. condensation, to interrupt the mechanism.
14

FUNCTION OF MAJOR
MECHANICAL PARTS (BOmOM VIEW)
Relay gear drive lever
Slow brake lever I
x
Loading relay gear
Capstan D. D. motor 3
o=
Reel belt @-
d
Reel sensor 7
Brake solenoide 5
()
/o
IO Supply loading gear
d Reel pulley
No.
Function
No.
Function
Slow brake lever
Gets in contact with the capstan D.D. motor linking to
the master cam in the slow still mode, and brakes it to a
certain degree.
Capstan D-D. motor
A motive power which runs the tape. It transmits the
power via the reel belt.
Reel belt
Transmits the power to run the tape to the reel pulley.
7.
Reel sensor
An element which sheds the light onto the reflection
plate affixed to the bottom side of the reel disk, and
detects the rotation of the reel disk through receiving
the reflected light.
9.
Take-up loading gear
Shifts the take-up pole base and guide roller via the
loading relay gear, and applies the tape around the
durm assembly, as well as transmits the power to the
supply loading gear.
5.
6.
Brake solenoid
Adsorbs and holds the brake shifter in the fast forward
and rewind modes, and releases it in the stop mode.
Reel pulley
Transmits the power of the capstan D.D. motor to the
reel disk via the reel idler.
10. . Supply loading gear
Shifts the supply pole base and guide roller via the
take-up loading gear, and applies the tape around the
drum assembly.
11.
Relay gear drive lever
Transmits the movement of the master cam to the
take-up loading gear via the loading relay gear.
15

ADJUSTMENT, REPLACEMENTAND
ASSEMBLY OF MECHANICAL UNITS
Here we will describe a relatively simple service
work in the field, not referring to the more
complicated repairs which would require the use of
special equipment and tools (drum assembly
replacement, for example).
We are sure that the easy-to-handle tools listed
below would be more than handy for periodical
maintenance to keep the machine in its original
working condition.
TOOLS NECESSARY FOR ADJUSTING THE MECHANICAL UNITS
The following tools are required for proper service and satisfactory repair.
These Jigs are used for checking and
adjusting the reel disk height
A/C Head Tilt Adjusting Jig
These Jigs are used for checking and
6 Cassette Torque Meter JiGVHT-063 CZ
for checking and adjusting the
torque of take-up for measuring
Tension Gauge (3009) .
JiGSG0300 BF
There are two gauges used for the
7
tension measurements, 300 g and
Tension Gauge (2.Okg) JiGSG2000 BS . w 2.0 kg.
Hex Wrench (0.9mm)’
JiGHW0009 AE
<
These Jigs are used for loosening or
8
Hex Wrench (1.2mm)
JiGHW0012 AE
tightening special hexagon type
screws.
Hex Wrench (1.5mm)
JiGHW0015 AE
Alignment Tape (PAL)
VROCPSV
11 f4sz$zg
This tape is especially used for
9
electrical fine adjustment.
Alignment Tape (NTSC)
VROATSV
VRONBZGS
10
Drum Replacing Jig
JiGDT-0001 BG
This is used for replacement of the
VCR’s upper drum.
16

No.
Jig Item Part No.
Code
Configuration
Remarks
This Jig is used with the tension
11 Tension Gauge Adapter JiGADP003 BK
ecih
gauge. Rotary transformer
clearance adjusting jig.
12
Special Bladed Screwdriver
JiGDRiVERH-4 AP
This screwdriver is used for adjusting
the guide roller height.
13
Tension Band and Plate JiGDRiVER-
BM
This Jig is used for adjusting the
Adjusting Jig tension band and tension plate.
14 Torque Driver JiGTDl200 CB
This is used to screw down resin-
made parts: the specified torque is 5
kg-
This Jig is used for height
JiGDRiVER 10-7 AS adjustment of the A/C head and X-
position.
15
Box Driver
JiGDRiVER 1 O-4
AV &@
This Jig is used for height
0adjustment of the retaining guide.
16
Reverse Guide Height Adjusting
JIGRVGH-F18 BU
This Jig is used for height
Jig
adjustment of the reverse guide.
17

MECHANICAL PARTS REQUIRING PERIODICAL INSPECTION
Use the following table as a guide to maintain the mechanical parts in good operating condition.
1000 1500 2000
Possible symptom encountered Remarks
;uide roller ass’y
Cl q 0 0 Abnormal rotation or
significant vibration
;upply impedance roller
0 0 q 0 requires replacement.
;upply impedance roller
qq
Clean with pure high
Lateral noises
)nner hole and shaft) quality isopropyl alcohol.
. Head occasionally blocked
;upply impedance roller flange q q q q Clean tape contact part
Retaining guide q
0 q q with the specified cleaning
liquid.
slant pole q q q 0
Video head (upper drum ass’y)
q 00 q
0 Cl Poor S/N ratio, no color
Full-erase head q
0 q
0 Poor colour, beating
Clean tape contact area
AIC head
cl q q
0 Sound too small or distorted with the specified cleaning
Poor flatness of the envelope with liquid.
Lower drum ass’y
cl cl q 0 alignment tape
Capstan D.D. Motor q cl q 0 No tape running, uneven color
Pinch roller q
Cl q 0 No tape running, tape slack
No tape running, tape slack, no
Reel belt
cl
0Clean rubber and rubber
fast forward/rewind motion contact area with the
specified cleaning liquid.
Loading belt
q
0
Cassette not loaded or unloaded
Cassette loading belt cl 0
Tension band ass’y
0Lateral image swing
Loading Motor 0Cassette not loaded or unloaded
Replace the roller of the
cleaner when it wears
AHC (Automatic Head Cleaner) 0 0 down. Just change the
AHC roller assembly for
new one.
Reel block* See the chart below.
* See the table below for servicing the reel block parts.
SupplyTTake-up reel disks IJA
A 0 No tape running, tape slack Clean with pure high
quality isopropyl alcohol.
Video search brake lever 0
Idler gear ass’y
0No tape running
Reel Pulley
CIA
00
Main supplyfiake-up brake levers 0 Tape slack
NOTE:
0: Part replacement.
Cl : Cleaning (For cleaning, use a lint-free cloth dampened with pure isopropyl alcohol).
A: Oil refilling (The indicated point should be lubricated with high quality spindle oil every
1000 hrs).
If the reading is out of the specified value, clean or replace the par-t.
18

REMOVAL AND REASSEMBLY OF
CASSETTE HOUSING CONTROL ASSEMBLY
l Removal
1. Set the cassette ejected condition in the cassette
eject mode.
2. Unplug the recorder from the main source.
3. Follow the procedures below in the specified
order.
a) Remove the cassette loading belt 0.
b) Disconnect the FFC (Full Flat Cable) a.
c) Remove the cassette housing installation
screws 0.
d) Slide and pull out the cassette housing control
assembly @upward.
4. In removal and reassembly, take care not to hit
the cassette housing control assembly or tools
against the guide pin, drum, or the like
thereabout.
5. Place the unit in the eject mode in removal or
reassembly of the cassette housing control
assembly.
6. Load the cassette once onto the cassette housing
control assembly after reassembly. (If the
cassette housing control assembly normally
operates after this, the phases of mechanism and
the cassette controller are accurately adjusted
after ej ecti on.)
MECHANICAL OPERATION CHECK
WITHOUT CASSElTE
When power is on, the general operations of the
mechanism can be checked without a cassette.
ble)
loading Note the following points.
Check video search rewind and rewind, rotating
the take-up reel disk @ by hand (in either
normal or reverse direction). If it is not rotated,
the reel sensor works to shift the mechanism to
the eject mode.
When the belt is
detached, tuck it
as in the figure so
that it is kept free
w
n
from grease.
49
4
When the stop button is pressed, the mechanism
does not stop at a normal stop position. It shifts
to the eject mode and stops.
When the stop button is pressed in the playback,
video search rewind, and video search forward
modes, the supply reel disk 8 keeps on rotating
for several seconds for elimination of tape slack
in the course of shifting to the eject mode. In
such a case, rotate the take-up reel disk @
somewhat by hand, and the supply reel disk @
stops, which can reduce the working time.
insert the tab of
the Cassette housing
control assembly to
the mechanism chassis.
Figure1 -1.
REPLACEMENT OF WORM WHEEL
ASSEMBLY
Reassembly
1.
2.
3.
.
Before installation of the cassette housing
control assembly, place the unit in the stop mode
with the power on, then unplug the power cord.
(The main body is placed in the eject mode.)
&. Follow the procedures for removal in the reverse
order.
Notes:
Be sure to unplug the power cord in removal and
reassem blv.
Cassette switch
Worm bracket
Keep the cassette loading belt free from grease. Cassette housing frame
FO
/
tight screw
In case of its adhesion, clean the belt.
Worm wheel ass’y
In using a magnet screw driver, be sure to keep it
Figure l-2.
away from the A/C head, FE (Full Erase) head, or
the drum.
19

VT-341 8X
W-51 18X
l Removal
1. Unsolder the cassette switch connectors (No. 16,
17) from the start sensor PWB.
Start sensor PWB
Cassette switch
connector
Figure l-3.
2. Lift the start sensor PWB pressing the two start
sensor PWB fixing hooks inward.
Start sensor PWB
5.
6
Place the slider pin just above the worm wheel
assembly (Figure l-7). (The retainer of the slider
is locked at two positions. So unlock it as in the
Figure 1-8.)
Pull out the worm wheel assembly toward you
pressing the switch lever upward. (Figure l-7)
itch lever
Phase ge
shaft
Tally mark
‘%ut washer
Figure l-7.
3.
4.
Figure l-4.
Unscrew one B tight screw to detach the worm
bracket.
Note:
The worm shaft bearing can easily come-out of
position. So be careful not to lose it.
-Worm bracket
LWorm wheel ass’y
Figure l-5.
Remove the worm shaft assembly, pulley, and
cassette loading belt all from the cassette
housing frame (R).
Worm shaft a
Cassette housing
frame (R)
Figure l-6.
20
the (L)side
/-Slider
Cassette housing frame
(R)/(L) side
Figure l-8.
Reassembly
Turn the phase gear clockwise until the slider
comes to a halt in the cassette insertion
direction. (See the Figure l-9.)
Insert the set up worm wheel gear assembly into
the cassette housing frame (R), matching the
mark on the phase gear with the mark on the
worm wheel gear. Detach the cut washer on the
phase gear assembly and the phase gear for
easier installation of worm wheel assembly.
Note:
Make sure that the slider pin is in the groove of
the drive gear arm.