SHARP VT-3428X, VT-51 Service Manual
SERVICE
MANUAL
TV/VCR COMBINATION
VIDEO TV
Chassis No.
VP-3
VT-3428X
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.
FEATURES
n
W
TV/VCR Integration for Easy Operation
W
Single Built-in Tuner for Simple Operation
n
Timer Programme Setting by the On-Screen
Display
W
Auto Tracking Control
n
Full
Auto Head Cleaning System
n
On-screen Display with Menu Screen Guidance
H
Wake-Up/Sleep Timer
n
NTSC
Simple Playback
r
CONTENTS
2-way Child-Proof Lock
@To
Lock Operation Mode
@To
Lock the Power Off.
n
Ret Index with DPSS (Digital Programme Search
System)
n
Full Auto Play Function
n
Auto Repeat Playback
n
Front input terminals Audio/Video
VT-5128X
\
l
SPECIFICATIONS
l
IMPORTANT SERVICE NOTES
. LOCATION OF USER’S CONTROL
. DISASSEMBLY AND REASSEMBLY
. ADJUSTMENT OF THE TV ELECTRICAL
CIRCUITRY
. PRECAUTIONS IN REASSEMBLING
. FUNCTION OF MAJOR
. ADJUSTMENT, REPLACEMENTAND
ASSEMBLY OF MECHANICAL PARTS
ADJUSTMENT OF THE VCR ELECTRICAL..
.
CIRCUITRY
. TROUBLESHOOTING
........................
.............
.........
.............................
MECHANICALaPARTS
............................
...................
........
.
.......
..
Page
2
3
4
6
8
15
16
18
42
45
l
OVERALL SCHEMATIC DIAGRAM
l
CHASSIS LAYOUT OF TV SECTION
.
BLOCK DIAGRAM OF TV SECTION
.
DESCRIPTION OF TV SECTION
SCHEMATIC DIAGRAM
.
CHASSIS LAYOUT OF VCR SECTION
l
BLOCK DIAGRAM OF
. DESCRIPTION OF VCR SECTION
SCHEMATIC DIAGRAM
. PRINTED WIRING BOARD ASSEMBLIES
. REPlACEMENT PARTS LIST
.
PACKINGOFTHESET
.................
VCRSECTION
.................
.................
........
.......
.......
............
......
......
...
Page
57
59
61
65
79
81
91
97
105
134
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
/
W-3428X
VT-51 28X
SPECIFICATIONS
I
Model
Reception channels
I-
VHF band
UHF band
Receiving System
AV Input
Screen 34 cm “Viewable” measured
diagonally,
Antenna input
Audio output
Speaker
Rated voltage
Rated frequency
Power consumption 77 W
Video cassette format
I
Video recording system
I
Number of Video Heads I
Video signal
(PlaybacWRecording)
Recording/playing time
Tape width
Tape speed
Operating temperature
I
Storage temperature
Weight
Dimensions
Video input
Audio input
Supplied accessories Operation manual, wireless remote control unit,
output
output
I
1
1
I
1
13.7
388(W)
kg
VT-3428X
VHF :
NZl - NZll
CATV
: Sl -
UHF :
44.25 MHz - 463.25
(VL: 45.25 - 168.25 MHz/VH: 175.25 - 463.25
471.25
MHz -
PAL B/G
90”
deflection
75
ohm unbalanced
Max.
8 cm round type x 1
AC220
50
VHS
Two rotary heads, helical scan
480
minutes max. with
12.7
x
PAL
NTSC
380(H)
:
23.39 mm/set (SP)
11.70 mm/set (LP)
:
33.35 mm/set (SP
16.68 mm/set (LP
11 .12 mm/set (EP
5°C
-20°C to
x
395(D)
mm
Vp-p,
1
.O
1.OVp-p,75ohm
Phono
jack:
0.5 Vrms, 10 kohm
Phono iack: 0.5 Vrms.
R03 (AAA)
S41
E21 - E69
MHz
885.25
MHz
PAL
51
cm “Viewable” measured
diagonally, 90’ deflection
1.5
W
pc
V -
240
V
Hz
I98W
standard
2
PAL
E-240
mm
playback only)
playback only)
playback only)
to
40°C
60°C
24.2
kg
510(W)
x
499(H)
75 ohm
1
kohm (54%
battery x 2
VT-51
tape
MOD)
28X
MHz)
x
483(D)
I
I
mm
*Design and specifications are subject to change without notice.
2
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-3428X: When repairing the circuit, be sure not to increase the high voltage to more
than
25.3 kV,
VT-5128X: When repairing the circuit, be sure not to increase the high voltage to more
than
29.3 kV,
2.
m-3428X: To keep the set in a normal operation, be sure to make it function on
22.0 kV
been factory
VT-5128X:
mm-
If there-is a possibility that the high
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.
To keep the set in a normal operation, be sure to make it function on
25.0 kV ,+ 1.5 kV
factory
(at beam 0
(at beam 0 4) for the set.
+
1.5 kV - 2.0 kv
-Adjusted to the above-mentioned high voltage.
(at beam
-Adjusted to the above-mentioned high voltage.
,A)
for the set.
(at beam
1100
,A)
vo,ltage
800 fi)
in the case of the set. The set has been
fluctuates as a result of the repairs, never
in the case of the set. The set has
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
capacity networks, mechanical insulators etc.
3
resistor-
(REARI
I
0
n
FF
(Forward video
search) BUTTON
STOP/EJECT
BUlTON
VT-51
28X
2,
-I
REW
(Reverse video
i
. .
: :
POWER
BUTTON
P
SENSOR ARE
FOR REMOTE
CONTROL
VIDEO INPUT JACK
AUDIO INPUT JACK
NOTES:
l Use the RESET button if the
VIDEOAV
Timer, etc.) cannot be operated.
1
mode (ex.
EA ’
Program
-
-
REC
BUlTON
I
POWER/WAKE-UP
TIMER INDICATOR
VOLUME UP/DOWN BUTTONS
CHANNEL UP/DOWN BUl-t-ONS
f-4
1
J
AESR
l REC
VVOL
A V
CH
A
search) BUTTON
MAIN POWER SWITCH
VIDEO OUT JACK
AUDIO OUT JACK
ANTENNA IN TERMINAL
VT-3428X
MAIN POWER SWITCH
(01) _J
(01)--l
0
2
0
In
c
K
51c1
vi
(1
0
z
-I
510
0
I
AUDIO OUT JACK
ANTENNA IN TERMINAL
-
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
Inserting the Batteries
The remote control operates on two
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.
Press
Down
-
Battery
Cover
-4-P
Slide off
l You can set clock and timer recordings using the remote control.
Slide on
0
Open the battery cover. (Remove any old
batteries that may be in the remote control.)
@
Insert
w ab tteries and match their polarities
ne
( + and - ) with the markings inside the compartment.
0
Replace the cover.
R03 (AAA) 1.5
SENSOR AREA
FOR REMOTE CONTROL
Clock setting:
see SETTING THE CLOCK
Timer recording: see RECORDING WITH THE TIMER
NOTES:
l Do not subject the remote control to impact, water or excessive humidity.
l
The remote control may not function if the photoreceptor window of this product is in direct
sunlight or any other strong light. If so, move the product or alter the lighting.
l Incorrect use of batteries may cause them to leak or burst.
l Do not mix old and new batteries, or mix the brands used.
l
Both rechargeable and disposable batteries are available. Read the battery warnings and
do not try to recharge disposable batteries.
l Remove the batteries if the remote control will not be used for a long time.
POWER ON/OFF button (0
WAKE-UP TIMER
SLEEP
TIMER
XIANNEL
SELECT
buttons
TIMER ON/OFF button
PAUSE/STILL button
COUNTER RESET button
I)
EJECT/LOAD button
MUTE button
DISPLAY button
VOLUME ADJUSTMENT buttons
CHANNEL UP/DOWN buttons
(TRACKING buttons)
PROGRAMME button
MENU button
SET button
STOP button
SPILP button
PLAY button
FF
button I
Video Search
REW button I Reverse
Video Search
F&ward
U--3428X
VT-51 28X
DISASSEMBLY AND
n
TV SECTION
1.
Remove the nine screws off the rear cover.
1.
Remove the ten screws off the rear cover. (VT-51 28X)
2.
Disconnect the F connector from the main
the anode cap and the CRT PWB unit from the CRT.
3.
After disconnect the coating earth from the CRT unit and take out the unit.
4.
Remove the two screws from the main PWB and separate the
5.
Remove the three screws from the power
(VT-3428X)
(VT-3428X)
PWB
and G connector from the power
PWB
and separate the
R’EASSEMBLY
PWB
from the video unit.
PWB
(VT-51 28X)
PWB
and disconnect
from the video unit.
6
DISASSEMBLY AND REASSEMBLY
6.
Remove the CRT PWB,
the main PWB upright.
7.
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 and front power switch remote control
degaussing
coil connector G off position.
(Continued)
PWB.
Place
n SERVICING THE
<Repairing the TV unit>
Unhook the power PWB and place it on the left
hand of the set. Set up the mother PWB as shown
below.
PWBs
-Mother
FRONT
PWB
<Repairing the TV and VCR units>
Unhook the
VCR unit, and place it as shown here. Connect the
cables
start repairing.
PWB/mechanism
(AB),
(AD) and (PC) to the mother
assembly from the
TV Unit
PWB
to
W-3428X
VT-51 28X
l PRECAUTIONS
Calling the service mode
I,
(1) Place the set in the stand-by mode.
(2)
Hold down the CH UP key
POWER button ( bl ) of the set. Now the set is in the service mode.
Clearing the service mode
2.
(1)
There are two ways to clear the service mode. Press the MENU key on the remote control gun
(2) Or place the set in the stand-by mode again.
Display in the service mode
3.
ADJUSTMENT OF THE
TV ELECTRICAL CIRCUITRY
(CH A)
of the set for 2 seconds or longer and at the same time press the
ROM No. in the microprocessor
L-------d
r-------------------~
i 1100 0100 0010 1101 I’ +VCJICdata
L---------------,,,,~
*SERVICE MODE :
*SERVICE MODE :
*SERVICE MODE :
*SERVICE
*SERVICE MODE :
*SERVICE MODE :
*SERVICE MODE :
*SERVICE MODE :
*SERVICE MODE :
L---l
MODE :
01
02
03
04
05
06
07
08
09
RED
INT
GRN
INT
BLUE INT
VERTAMP
VERT
LIN
VERT
POS= O-63
HOR PHAS
HI-VI
HGAlNl
+
Adjustment item Nos.
data
=
O-63
=
O-63
=
O-63
= O-63
=
O-63
=
lo-55
= O/l
/2/3
=0/l
01-l
(O-63,1 O-55,0-3, O- 1)
General adjustment items
2
*SERVICE MODE :
*SERVICE MODE :
*SERVICE MODE :
10
HGAlN2
11
INTSEL
12
CALKILL
T-
Ls
electable
=0/l
= O/l
=0/l
by the CH
8
Basically fixed
Variable by the VOL
Aw
key
Aff
key
SCREEN/BACKGROUND ADJUSTMENT
i/T-3428X
VT-51 28X
.
1.
Screen Adjustment
1.
Receive the “AV-CH” signal. Keep the blue
background off.
2.
Reset “video adjust” mode.
t
2.
Background Adjustment
1.
Receive
PATTERN” signal.
2.
In the video adjust mode, adjust the brightness
and contrast.
8
Bright portion:
l Dark portion:
Keep the colour adjusted at “00”.
Adjusting Conditions
“WHITE BALANCE ADJUSTMENT
120
nit
20
nit
1.
Call the service mode and take the step below.
0
Screen control:
Look at the
control so that the
turn from “1 II to
1.
Call the service mode and take the step below.
l
Red intensity :
l
Green intensity :
l
Blue intensity :
Pick up the service mode numbers
Adjust the
12,300”K (x
The
“CA-100 Minolta
be used as a colour thermometer.
Adjusting Procedures
VCJ IC
data on the screen. Adjust the
10th
figure from left should
“0”.
To be 0 here too.
f
To turn to 0 here.
colour
temperature as follows.
=
0.272 + 0.015,
y =
CRT Color Analyzer” should
“2”
and
0.275 It 0.015)
“3”.
3.
Focus Adjustment
1.
Receive “monoscope pattern” signal.
2.
Reset the video adjust mode to have the Video
Normal Position.
1.
Adjust the focus control to have the best focus in
the areas between the pattern’s center. and its
both ends.
Adjust point
9
W-3428X
VT-5128X
HORIZONTAL/VERTICAL CIRCUIT ADJUSTMENT
0
Figure
0
Figure
1.
2.
I
1.
Receive “PAL monoscope pattern” signal.
2.
Reset the video adjust mode to have the Video
Normal position.
I. Call the service mode and take the steps below.
l
VERT-AMP
Select the service mode number
VERT-AMP
l
VERT-LIN
Select the service mode number
VERT-LIN
Figs. 1 and
l
VERT-POS
Select the service mode number “6”. Adjust the
VERT-POS
center of the screen. (See
l
HOR-PHAS
Select the service mode number
HOR-PHAS so that the horizontal center be at the
center of the screen. ( See
Adjusting Conditions
Adjusting Procedures
(vertical size):
“4”.
Adjust the
to have 10% overscan.
(vertical linearity):
‘5’.
Adjust the
to have optimum vertical linearity. (See
1.)
(vertical center):
so that the vertical center be at the
Fig.
3.)
(horizontal center):
“7’.
Adjust the
Fig.
4.)
~~
:
.
.
. . . . . . .
..--
.
:
.’
.*
i
.
‘.
.
$
-.
.
-.
-.
.
-......-
.
‘.
.
Figure
Figure
3.
4.
‘.
:
-.
.
-.
.
.
.
‘.
:
,
a* ;
*.-
,
:
.
.
_
l ‘
,
:
IO
W-3428X
VL5128X
PURITY ADJUSTMENT
Adjusting Conditions
1.
Before the purity adjustment, warm up the set
with beam current of more than 700
longer than 30 minutes (400 PA for the
I
a
b
model).
2.
Receive the qreen-only signal and adjust the
beam current to about 770 @I (500 fi for the
model).
3.
Fully
degauss
the CRT with the
degaussing
,uA
coil.
for
14”
14”
Figure A.
Adjusting Procedures
Notes:
Left
.
A..*.-...*.
::::::::::::::::::::~.
,
. . . . . . . . . . . .
:.~:.>:.y*.~;
::::~::::::::::::::::::::
s:~:::::::::::::::::~:::
::::::::::::::::$::::
I
:::::::::~~::::::::::::::::::
. . . . . . . . . . . . . . .
~~~,:.:.:,~.:.:.:.:.:.:.:
I
:::::::~::~~~.:~:::::
I
f
:::::::::::::::::::::::::::::::
:::::::::::~:~:::::::::
I
:::~~.:::::~:::::::::::::::::
:::~.::~.:::::~~::::~.::
~~
. . . . . . . . . . . . . . .
; ~~~~
::::::~::::::::::::::::::::::
\
::::#:::::::x:::$::.
\ :::::::::~.::::::~::::::..
“::::~::~:y$.:.~
~
Beam landing equally outwards.
Figure
B.
t
Left
. . . .
..:.:::::::::::::::::..
.::;~:~:~:; \
..:.:.:.:.:.:.:,~.:.:.:.:.:.
..:.:.:.:.:.:.:.~.:.:.:.:.:
:::::::~:::::::::::::::~~:::
:::::::::::::::::::::::::::::::
:~:::::::::::::::::::::::::::
2.. ..A........ *.5..* ..A..
;y:y$$:::::::y$$$$:
:::::::::::::::::~~::::::::::
:::::::::::::::::::::::::::::
.:.:.:.:.:.:.:.:.:.:.:.~.:.:.
:.:.I:.:.:.:.:.:.:.:.:.:.:.:.:
i.....~......................
:::::::::::::::::::::::::::::::
::::::::::::::::::::::::~:::::
:::::::::~:::::::::::::::::::
:::::::~:::::::::::::::::::::
:::::::~:::::::::~::::~:::
.:.:.ff~:.:.:.:.:.:.~:.:.:.
:.:.:.:.:.:.:.~.:.:.:.:.~
:.:.:.~.:.:.:.:.:.:.~~
:.:.:.:.:.~.:5.:.:,:.:.:.:
..:.:.:.:.:.:.:.:.:.:.:.:
vZ.*.5..~.5V
il
\
I
,
,
i
1
I
I
I
A...
/
*..
s.5.. fS%S. .. . .
.
y.:,:.:.:.*.v
Beam landing shifted to the right.
Figure
C.
Right
Right
.
.v.*.
. .
,::$yjg::>g
..~:.:.:.:.~:.:.:.:.:.:.:
.:.>>>:.:.p:.>~.~. \
..:.:.:.:.:.:.:.:.:.:.:.:.:.:.:
:::::::~~.::::::::::~::
:::::::::::::~:::~.:::.
::~:::::::::::::::~::::::
@Jg$g$~~
g$$J#jgg:$
::::::::~::::::::::::~:::::::
:::::::::::::::::::::::::::::::
:::::::~:::::::::::::::::::::
~~~~.:.
:::::::::::::::::::::~::::~::
.~.:.>‘:.:.~.~.;.~.:.:.~.
:.:.:.:.~.:.:.~.:.:.:.:.:
::::::;::::::::::::::::::::::::
:~:::~:::::~.::::::~.:::::::;
.:.~:,~~:.~..~X.:.:.
s::~::::::::::::::::~::::
13
\
1
I
I
,
I
1
I
::::::y$::::::::::::::::
.7...5......,.....5.,
I
. . . . . . . . . . . .
/
v.;.:.:.~
,
l
Static convergence should be roughly adjusted.
l
The purity magnet should be positioned where
the magnetic field is zero.
Adjustment:
During the adjustment, keep the set facing the east.
1.
Observe the spots “a” and
with a microscope. Adjust the purity magnet to
have these spots at the specified landing
positions.
2.
If the right and left spots are
outwards from their landing positions (shown in
Fig.
B),
push the deflection yoke forwards for
proper positioning.
3.
If both the spots are shifted to the right or left
(shown in Figs. C and
angle of the purity magnet for proper
positioning.
4.
Make sure that the center spot
and left spots are in their specified landing
positions. Check the four corners of the CRT
screen.
See if all the landing positions are
satisfactory with the Rank “B” specifications.
5.
If any
colour
other than green appears, pull the
deflection coil backwards.
Landing too outwards: Deflection yoke to push
“b”
(shown in Fig. A)
dqually
D),
adjust the opening
as
deviated
well as the right
forwards.
Left
.
A55..
.
:::::::::::::~~::::..
/ .5..55............55
.:,:.:.:.:.:.:f.:.:.:.:.~.
~:.v.-.~...*
. . . . . . . . . . . . . .
>:.f:.:*:.:.:.:.>:.~.:.:.
;
~~~~
. . . . . . . . . . . . . . z.
.:e:.:.>:.:.:.:.:.:.:.>:.:.:.
1 .r:‘:‘:‘:‘:‘:‘:‘:‘:‘:‘:’
. . . . . . . . . . . . . . .
.
. . . . . . . . . . . . . . .
:.~.:.:.~.:.:.~.:.:.:.:.:
. . . . . . . . . . . . . . .
.
. . . . . . . . . . . . . . .
*...*A. ..,.........A.......
I
. . . . . . . . . . . . . . . .
.:.:.:.:.:.:.:.>:.:.:.:.:.:.:.
. . . . . . . . . . . . . . . .
.:.:.:.:.:.:.:.:.:.:.:.>:.:.:.
I
:.~.:.:.>:.:.:.:s.:.~.:.:
. . . . . . . . . . . . . . .
I
:.~:.:.:.:.:.:.:.:.:.:.:.f:.:
.:.:.:.:.:.:.:.:.:.:.:.:.:.:...
I
:.~.:.:.~:.:.:.:.:.:.:.:::
. . . . . . . . . . . . . . .
:*:‘:.:.:.:.:.:.:.:.:.:.:.:.:..
.:.:.:.~.:.:.:.:.:.:.:,p:
. . . . . . . . ...*.....
... .
. . . . .
.
. . . . . . . . . .... . . .
:.x.:.:.>:.
. . . . . . . . . . . . . . .
;
\
\ ::pJ:$.:$#~..*.
[fl
.
.:.:.:.:‘:.:.:.:.~:.:.:.>:
:.~.:.:.:.:.:.:.:.:.:.:.:.:.
::$::::::p+:.:.:.:.:...
.::~~:$::*$.J$.~
. . . . .
Right
Landing too inwards : Deflection coil to
backwards.
6.
Receive the monoscope pattern signal.
7.
Set the raster rotation at
“0”
position with the set
facing the east.
Adjustment error: 0 + 2 mm
8.
Tighten up the deflection coil screws.
Tightening torque:
11 +
2 kg
pul
I
Beam landing shifted to the left.
Figure
D.
11
VT-3428X
VT-51 28X
CONVERGENCE ADJUSTMENT
Adjusting Conditions
RGB
This adjustment should be performed after
the purity magnet adjustment.
1.
Receive the crosshatch pattern signal.
2.
Set the brightness and contrast controls to the
5/l 0 and 1 O/l 0 positions, respectively.
Figure a.
RGB
Figure
c.
Wedge
4-pole
w----------~--L
..I.......... * . . . . *
“a”
magnet
6-pole
f
Figure
Figure
magnet
b.
BGR
:
I
I
..I..... .‘.
.
:
I
.
.
: I
’
I
.
.
I
*
-
I
.
*I
d.
,100"
C"
CRT neck
.
I
Adjusting Procedures
STATIC CONVERGENCE
1.
Adjust the opening angle of the
and rotate the magnet to impose the blue line
over the red one.
2.
Adjust the opening angle of the
and rotate the magnet to impose the green line
over the blue one.
4-pole
6-pole
magnet
magnet
DYNAMIC CONVERGENCE
3.
Take the following steps for dynamic
convergence at the edges of the CRT screen.
l
Convergence in Fig a :
Insert the wedge “a”
deflection coil upward for correct convergence.
l
Convergence in Fig b :
Insert the wedges
he deflection coil downward for correct
convergence.
l
Convergence in Fig c :
Insert the wedge
deflection coil rightward for correct convergence.
l
Convergence in Fig d :
insert the wedge
deflection coil
4.
Stick the above wedges on the CRT, and apply
glass tape over them.
5.
Apply lacquer to the deflection yoke screw, the
magnet unit (consisting of purity,
pole magnets)
leftward
and’the
Finally receive the red-only signal to make sure
there is no mixture with any other
same with the blue-only signal.
in position, and tilt the
“b”
and
“c’
in position, and tilt
“c”
deeper, and tilt the
“b”
deeper, and tilt the
for correct convergence.
4-pole
magnet unit screw.
colour.
and
6
Do the
Purity magnet
L
3
Lacquer
12
1.
A/V Output Checking
VT-3428X
VT-51 28X
PERFORMANCE CHECK
Adjusting Point
1.
w
output
(J401)
1.
I
2.
A/V Input Checking
lANinput
(J802 1)
Receive the
modulation).
2.
Add a 75 ohm terminal resistor to the video output terminal.
3.
Add a
The output levels are as follows.
Note:
Make sure the video and audio outputs are as specified.
1.
Receive the
2.
Feed the external video and audio signals via the
3.
Using the CH
signals are being properly received. (The AV mode is available somewhere between
lo-kohm
Video output:
Audio output:
lch and 40
colour
terminal resistor to the audio output terminal.
colour
Am
key, call the AV mode and make sure the external video and audio
(max) ch.)
Adjusting Conditions / Procedures
bar signal
1
Vp-p +
2.61Vp-p +
bar signal.
(100%
3 dB
(0.71-l .41 Vp-p)
3 dB
(1.85-3.69 Vp-p)
white
colour
A/V
front jacks.
bar, audio : 400 Hz, 100%
t
f
3.
Protector Performance Checking
Protector
Performance
4.
Beam Protector Performance Checking
Beam
Protector
Performance
1. Receive the monoscope pattern signal.
2.
Apply
3.
Feed 25V in the same way and make sure the protector is activated.
1.
Receive the monoscope pattern signal.
2.
Ground any of the R, G and B cathodes on the CRT PWB.
3.
Make sure the protector is activated immediately.
20V
from the constant-voltage power supply to the cathode of
symbol on the
Note:
To reset the protector, press the
Note:
To reset the beam protector, press the RESET key.
PWB)
and make sure the protector is not activated.
RESETkey.
D607 (TP603:
no
13
W-3428X
VT-51 28X
PERFORMANCE CHECK
5.
Blue Background Checking
Adjusting Point
1.
Blue
background
c
6.
Record Index Checking
Record
index
In the SET UP mode, select the BLUE SCREEN function.
2.
Turn on the function. With any signal input,
Make sure also that the audio is mute.
3.
Turn off the function and make sure the blue background disappears.
1.
In the SET UP mode, select the
2.
Turn on the function to make recording. (Make sure the clock has been preset.)
3.
Check the recorded contents.
Note:
Make
sure
the channel and time
(Continued)
Adjusting Conditions / Procedures
make sure the background is blue.
REC
INDEX function.
are
recoded.
14
PRECAUTIONS IN REASSEMBLING
VT-3428X
VT-51 28X
MOUNTING THE
Initial setting is indispensable
made in two ways; electrical and mechanical.
CASSETTE
before placing the cassette controller in the mechanism. The initial setting is
CONTROLLER
Electrical setting:
Make a short-circuit between TP8804 and TP8805, both located at the center on your side on VCR
with a 22 ohm resistor and be sure that the mechanism is back to its initial setting position
the cassette controller in position. (This method is used when the mechanism has been already set on its
PWB.)
(*l).
Now place
PWB,
Mechanical setting:
Cassette control
r----
COUPLING THE MECHANISM TO THE
Match the mechanism’s projections with the two symbols (round reference and oval sub-reference) on the
VCR PWB. Place the mechanism straight down in position with due care so that the mechanism chassis’s
outer edges should not damage any parts nearby.
Tighten up the two screws (one for fixing the mechanism and the head amplifier shield, the other on the
VCR
PWB’s
soldering side and located near the loading motor) to fix the mechanism and VCR PWB.
Reconnect the
PWB.
FFC
cables
(EB, EF
and EH) and harnesses (ED and
drive gear
Phase matching point
PWB
EG)
between the mechanism and VCR
Turn the loading motor’s
pulley feed gear using a
screwdriver and be sure
that the mechanism is
back to its initial setting
position
the cassette controller in
position. (This method is
applicable for the
mechanism alone.)
(*l).
Now place
Parts to pay attention to:
Start and end
Record tip switch:
Take special care of the MC-EC connector
(board
and VCR
to
PWB.
.sensors:
Q8803,Q8804
58801
board) between
the mechanism
W-3428X
VT-5128X
I
t
FUNCTION OF MAJOR MECHANICAL PARTS
19
Drum Motor
20
Drum
Full Erase
Head
Ass’y
Supply Pole
Base
Ass’y
Main Supply
Brake Lever
Tension
Arm
Ass’y
Ass’v m
Auto Head Cleaner
f
P
P
/
Take-Up Pole
Base Ass’y
Ass’y
(TOPVIEW)
A/C Head
Pinch Roller
Lever
Pinch Drive Car
Pinch Drive
Lever
Reverse Guide
Main Take-Up
Brake Lever
Cassette
Housing
Drive Gear
Ass’y
Ass’y
Ass’y
n
SUPPlY
No.
Full erase head
1.
Erase the whole records on the tape in the recording
mode.
3.
Tension arm
Detects the tension of tape while running, and brakes
the supply reel disk via the tension band.
7.
Main supply brake lever
Brakes the supply reel disk to prevent tape slackening
when the unit is stopped in fast forward or rewind
mode.
9. Main take-up brake lever
Brakes the take-up reel disk to prevent tape slackening
when the unit is stopped in fast forward or rewind
mode.
ass’y
Function
ass’y
Take-Up
Lock Lever
@
Loading
Motor
No.
Reverse guide
13.
Pulls out the tape and controls the tape drive train
height with the upper and lower guides.
Pinch roller lever
16.
Press-fits tape to the capstan during tape running-The
right protrusion switches the clutch of the cassette
housing control assembly in “tape eject”, and makes
the mechanism eject tape,
Loading motor
18.
A motive power which drives the mechanism. It
transmits the power to the master cam and cassette
housing control assembly .
Function
ass’y
Reel Disk
16
FUNCTION OF MAJOR MECHANICAL PARTS
(BOTTOM VIEW)
Capstan
DD
Motor
o-
3
9
Take-up
Loading Gear
P
Reel Belt
Slow
Brake Lever
Master Cam
Cassette Housing
Drive Gear
Connect Gear 5
o++
@,
1
o-
@,
Clutch Gear
@
\
10
0
6
Reel Pulley
0
8
Shifter
0
Clutch Connect Arm
No.
Slow brake lever
1.
Gets in contact with the capstan
the master cam in the slow still mode, and brakes it to a
certain degree.
3.
Capstan
A motive power which runs the tape. It transmits the
power via the reel belt.
4.
Reel belt
Transmits the power to run the tape to the reel pulley.
D.D.
motor
Function
D.D.
motor linking to
No.
6.
Reel pulley
Transmits the power of the capstan
reel disk via the reel idler.
8.
Shifter
Transmits the operation of the master cam to break
and loading gear.
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
drum assembly, as well as transmits the power to the
supply loading gear.
Function
D.D.
motor to the
VT-3428X
VT-51 28X
ADJUSTMENT, REPLACEMENT AND 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
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.
replacement, for example).
TbOLS
NECESSARY FOR ADJUSTING THE MECHANICAL UNITS
The following tools are required for proper service and satisfactory repair.
-
0.
-
Reel Disk Height Adjusting Jig
1
-
Master Plane Jig
2
-
3
A/C Head Tilt Adjusting Jig
-
4
-
Jig Item
Part No. Code
JiGRH0002 BR
JiGMPOOOl BY
I
9DAACH-A323U
I I
BX
Configuration
42
acD
Gauge Head
5
-
6
Cassette Torque Meter
-
Tension Gauge (3009)
7
Tension Gauge (2.0kg)
-
Hex Wrench (0.9mm)
a
Hex Wrench (1.2mm)
Hex Wrench (1.5mm)
-
Alignment Tape (PAL)
9
Alignment Tape (PAL)
-
JiGTH0006
JiGVHT-063 CZ
JiGSG0300
JiGSG2000
JiGHW0009 AE
I
JiGHWOOl2 AE
JiGHWO015 AE
VROCPSV
VROUBZFS
AW
BF
BS
1
I
f!3
Remarks
These Jigs are used for checking and
adjusting the reel disk height.
This Jig is used for setting the A/C
head tilt.
These Jigs are used for checking and
adjusting the torque of take-up and
supply reel disks.
This cassette torque meter is used
for checking and adjusting the
torque of take-up for measuring
tape back tension-
There
are two gauges used
tension measurements, 300 g and
2.0 kg.
These Jigs are used for loosening or
tightening special hexagon type
screws.
These tapes are especially used for
electrical fine adjustment.
for the
11
Tension Gauge Adapter
b
/ JiGADP003 / BK 1
18
This Jig is used with the tension
gauge. Rotary transformer
clearance adjusting jig.
No.
Jig Item
Part No. Code
Configuration
Remarks
Special Bladed Screwdriver
12
Torque Driver
14
Box Driver
15
Reverse Guide Height
17
Adjusting Jig
JiGDRiVERH-4 Ap
JiGTDl200
JiGDRiVER
JiGDRiVER 10-4 AV
JiGDRiVER
JiGRVGH-F18
1
lo-55
O-7
AR
CB
AS
BU
This screwdriver is used for adjusting
the guide roller height.
This is used to screw down
made parts: the specified torque is
-
C
/
:
kg-
This Jig is used for height
ment
of the A/C head and X-
position.
This Jig is used for replacement of
the SI roller.
’
This Jig is used for height adjust-
ment of the reverse guide.
This Jig is used for height
ment
of the reverse guide.
resin-
5
adjust-
adjust-
19
W-3428X
W-51 28X
MECHANICAL PARTS REQUIRING PERIODICAL INSPECTION
Use
the following table as a guide to maintain the mechanical parts in good operating condition.
500
1000 1500 2000
hrs. hrs. hrs. hrs.
Possible symptom encountered
Remarks
Guide roller
Supply impedance roller
Supply impedance roller
(inner hole and shaft)
Supply impedance roller flange
Retaining guide
Slant pole
Video head (upper/Lower drum
ass’y)
Full-erase head
A/C head
Capstan
Pinch roller
Reel belt
Tension band
Loading Motor
D.D.
ass’y
Motor
ass’y
q q q 0
Cl
q cl 0
cl
cl cl cl
cl cl cl El
q
Lateral noises
Head occasionally blocked
cl
cl q cl 0
El
q q
Cl
0 cl 0
cl q
0
Cl
0 Cl 0 Cl
0
0
Poor S/N ratio, no
Poor flatness of the envelope with
alignment tape
Poor
0
0
colour,
Sound too small or distorted
No tape running, uneven
colour
beating
cl q cl 0 No tape running, tape slack
III
No tape running, tape slack, no
0
fast forward/rewind motion
0
Cassette not loaded or unloaded
0
Abnormal rotation or
significant vibration
requires replacement.
Clean with pure high
quality isopropyl alcohol.
Clean tape contact part
with the specified cleaning
liquid.
Clean tape contact area
with the specified cleaning
liquid.
colour
Clean rubber and rubber
contact area with the
specified cleaning liquid.
.
Reel idler
Reel
Clutch gear
Main supply/take-up brake levers
AHC
NOTE:
ass’y
pully ass’y
ass’y
(Automatic Head Cleaner)
0:
Part replacement.
q
A
0 0
No tape running
0
00
0
0 Tape slack
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
hrs).
If the reading is out of the specified value, clean or replace the part.
Replace the roller of the
cleaner when it wears
down.
Just change the
assembly for new one.
AHC
roller
1000
,
20
VTg3428X
VT-51 28X
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 housing installation
screws 0 and
b)
Slide and pull out the cassette housing control
assembly upward.
\
.
a.
m
\
Cassette control
drive gear
2.
Follow the procedures for removal in the reverse
order.
Notes:
0
In using a magnet screw driver, be sure to keep it
away from the A/C head, FE (Full Erase) head, or
the drum.
Q
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.
0
Load the cassette once onto the cassette housing
control assembly after reassembly.
I
Drive angle of
cassette control
l-
Figure
l-2.
Figure l-l.
l
Reassembly
1.
Before installation of the cassette housing
control assembly, make a short-circuit between
TP8804 and TP8805, both located at the center
on your side on the VCR
resistor. Plug in the power cord. The cassette
control drive gear starts and stops just when a
tally mark appears in the mechanism chassis
window. Align this tally mark with the cassette
control drive angle’s mark, as shown in Fig.
to position the cassette control on the
mechanism chassis.
PWB,
with a 22 ohm
l-2,
TO RUN A TAPE WITHOUT THE CASSETTE
HOUSING CONTROL ASSEMBLY
1.
Be sure to make a short-circuit between TP8804
and
TP8805,
side on the VCR
before turning on the power.
2.
Plug in the power cord.
3.
Turn on the power switch.
4.
Open the lid of a cassette tape by hand.
5.
Hold the lid with two pieces of vinyl tape.
6.
Set the cassette tape in the mechanism chassis.
7.
Stabilize the cassette tape with a weight
to prevent floating.
8.
Perform running test.
Weight to prevent
Note:
The weight should not be more than
both located at the center on your
PWB,
with a 22 ohm resistor,
(500 g)
chanism chassis
Figure
1-3.
500 g.
21
1
W-3428X
VT-51 28X
REPLACEMENT AND HEIGHT CHECKING
AND ADJUSTMENT OF REEL DISKS
l
Removal (Supply and Take-up reel disks)
1.
Remove the cassette housing control assembly.
2.
Pull the tension band out of thetension arm.
3.
Remove the supply main brake and the take-up
main brake.
4.
Open the hook at the top of the reel disk, and
remove the reel disk.
Takeup
Tension Arm Ass’y
Supply reel disk
main brake
Take-up reel disk
Notes:
@Take enough care not to deform the tension
band during installation of the supply reel disk.
@
Be careful not to damage the supply main brake.
l
Reassembly (Take-up reel disk)
1.
Clean the reel disk shaft and apply oil to it.
2.
Install a new take-up reel disk onto the shaft.
3.
Check the reel disk height and reassemble the
take-up main brake.
Note:
Take care not to damage the take-up main brake.
After reassembly, check the video search rewind
back tension (see page
25)‘
and check the brake
torque (see page 28).
Height checking and adjustment
Note :
Place the master plane onto the mechanism unit,
taking care not to hit the drum (see Figure
l-6).
Figure
l-4.
Note:
When the tension band is pressed in the direction
of the arrow for removal, the catch is hard to be
deformed.
Figure
l-5.
l
Reassembly (Supply reel disk)
1.
Clean the reel disk shaft and apply oil to it.
2.
Install a new supply reel disk onto the shaft.
3.
Replace the tension band around the supply reel
disk, and insert it to the hole of the tension arm.
4 Check the reel disk height and reassemble the
supply main brake.
SUI
Set the master plane releasing the
reverse guide by a finger.
Figure
l-6.
22
l
l
Check that the reel disk is lower than part A but
higher than
part
If the height is not correct,
B.
readjust the reel disk height by changing the
poly-slider washer under the reel disk.
Note:
Whenever replacing the reel disk, perform the
height checking and adjustment.
Adjustment
1.
If the take-up torque is outside the range, clean
the capstan
pulley with cleaning liquid, then recheck the
torque.
2.
If the take-up torque is still out of range, replace
the reel belt.
D.D.
motor pulley, reel belt and reel
Notes:
Master plane
10 2 0.2mml
.
1
Reel disk
Reel disk height
adjusting jig
J
1
Mechanism chassis
1.
Hold down the torque gauge so that it may not
fly off.
2.
When checking the take-up torque, do not keep
the reel disk locked for a longer time.
CHECKING AND ADJUSTMENT OF TAKE-UP
Reel disk
Figure
I
l-7.
CHECKING AND ADJUSTMENT OF TAKE-UP
TORQUE IN FAST FORWARD MODE
0
Remove the cassette housing control assembly.
0
Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
turn on the power.
0
Setting
1.
Set a torque gauge to zero on the scale. Place it
on the take-up reel disk.
2.
Press the FF button to set the mechanism to the
fast forward mode.
0
Checking
1.
Turn the torque gauge slowly (one rotation
every 2 to 3 seconds) by hand in the take-up
i
I
direction.
2.
Check to see if the take-up torque is higher than
69 mN-m (700 gfcm).
TP8804
and
TORQUE IN REWIND MODE
0
Remove
0
Make a short-circuit between
TP8805,
on the VCR
turn on the power.
0
Setting
1.
Set a torque gauge to zero on the scale. Place it
on the supply. reel disk.
2.
Press the REW button to set the mechanism to
the rewind mode.
0
Checking
1,
Turn the torque gauge slowly (one rotation
every 2 to 3 seconds) by hand in the take-up
direction.
2
.
Check to see if the take-up torque is higher than
69 mN*m (700 gf-cm).
the
cassette housing control assembly.
TP8804
and
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
f
I
69mN.m (70Ogf.cm)
i
.i
69mN.m (700gf.cm)
or more
Figure
l-8.
guage
1
its maximum value.
(Red mark)
3
Take-up direction
is held at
Figure
The guage is held at
its maximum value.
l-9.
23
VT-3428X
VT-5128X
l
Adjustment
1.
If the
take-u1
the capstan
torque is outside the range, clean
Q
D.D.
motor pulley, reel belt and reel
pulley with-cleaning liquid, then recheck the
torque.
2.
If the take-up torque is still out of range, replace
the reel belt.
Notes:
1.
Hold down the torque gauge so that it may not
fly off.
2.
When checking the take-up torque, do not keep
the reel disk locked for a longer time.
CHECKING AND ADJUSTMENT OF TAKE-UP
TORQUE IN PLAYBACK MODE
Remove the cassette housing control assembly.
1.
2.
Make a short-circuit between
TP8805, both located at the center on your side
on the VCR
PWB,
with a 22 ohm resistor. Now
plug in the power cord and turn on the power.
Open the lid of the cassette torque meter, and
3.
hold it with two pieces of vinyl tapes.
Load the cassette torque meter into the unit.
4.
Put the weight (5009) on the cassette torque
5.
meter.
6.
Press the
REC
button to put the unit in
mode.
TP8804
and
REC
CHECKING AND ADJUSTMENT OF TAKE-UP
TORQUE IN VIDEO SEARCH REVERSE
MODE
l
Remove the cassette housing control assembly.
l Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
turn on the power.
l
Setting
1.
Push the PLAY button to place the
playback mode.
2.
Push the
video search reverse mode.
l
Checking
1.
Place the torque gauge on the supply reel disk,
and turn it counterclockwise very slowly (one
rotation every 1 to
torque is within the set value
Tii
gfcm)
Torque
REW
button to place the
2 seconds) and
gaug
TP8804
ass’y
ass’y
and
in the
in the
check that the
14.5 Ti mN*m (148
Set value EP
0
Checking
1.
Check that the torque is in the range of 8.8
3.8mNmm (90 +
2.
The torque fluctuates due to the rotational
deviation of the reel pulley
8.8 + 3.8mN.m (90 f 39gf-cm)
Figure
l-1
0.
39gfcm).
ass’y.
Use the center
of the fluctuation as the value.
3.
Place the
ass’y
in the SP record mode, and check
that the take-up torque is within the range.
0
Adjustment
If
the take-up torque in the playback mode is
outside the range, replace the reel pulley
ass’y.
Note:
Stabilize the cassette torque meter to prevent
floating.
Supply reel disk
Figure l-l
1.
Note:
Set the torque gauge securely on the supply reel
disk. If it is not secure, the measurement will be
incorrect.
+
l
Adjustment
If the take-up torque
is outside the range, replace the reel pulley
in video search reverse mode
ass’y.
Note:
The torque fluctuates due to the rotational
deviation of the reel pulley
the fluctuation at the value.
ass’y.
Use the center of
24
CHECKING THE FAST FORWARD BACK
TENSION
l
Remove the cassette housing control assembly.
l Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
turn on the power.
l
Checking
I. Push the FF button to place the
fast forward mode.
2.
Place the torque gauge on the supply reel
disk, and turn it clockwise very slowly (one
rotation every 2 to 3 seconds) and check that
the torque is I .5 *
Torque gauge
Supply reel disk
0.9mN.m
Figure
l-1
2.
Note:
0
Set the torque gauge securely on the supply reel
disk. If the torque gauge is not securely set on
the reel disk, measurement will be incorrect.
QMeasure the torque with the torque gauge’s
weight exerted on the reel disk.
(I 5 +
TP8804
ass’y
9gfcm).
and
in the
/
KZ::
2.
Place the torque gauge on the take-up reel
disk, and turn it counterclockwise very slowly
(one rotation every 2 to 3 seconds) and check
that the torque is I .3 2
gfcm).
Note:
@Set the torque gauge securely on the take-up
reel disk. If it is not secure, the measurement will
be incorrect.
QMeasure the torque with the torque gauge’s
weight exerted on the reel disk.
0.8mNem
(I 3 + 8
CHECKING THE VIDEO SEARCH REVERSE
BACK TENSION
Remove the cassette housing control assembly.
Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
turn on the power.
Checking
Push the PLAY button to place the
playback mode.
Push the rewind button to place the
video search reverse mode.
Place the torque gauge on the take-up reel disk,
and turn it counterclockwise very slowly (one
rotation every 2 to 3 seconds) and check that the
torque is within the set value 4 f
(41 f 17gfcm).
-
Torque gauge
TP8804
\-
,
,
‘f’
and
ass’y
in the
ass’y
in the
1.7mNam
.
CHECKING THE REWIND BACK TENSION
l
Remove the cassette housing control assembly.
l Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
turn on the power.
l
Checking
I. Push the REW
rewind mode.
buton
to place the
Torque gauge
Take-up reel disk
Figure
l-l
3.
TP8804
ki
,
/
ass’y
and
in the
Take-up reel disk
Figure-l-14.
Note:
0
Set the t
reel disk. If it is not secure, the measurement will
be incorrect.
QMeasure the torque with the torque gauge’s
weight not exerted on the reel disk.
orque
gauge securely on the take-up
CHECKING THE PINCH ROLLER PRESSURE
l
Remove the cassette housing control assembly.
l Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
turn on the power.
l
Checking
Push the PLAY button to place the
playback mode.
TP8804
ass’y
and
in the
25
m-3428X
VT-51 28X
Tension gauge
900-l
,200 g
2.
Visually check to see if the left end of the tension
pole is in alignment with the line
the center line of the SI roller. Readjust as
required in the following steps.
0.2mm
left of
Pinch rolle
Capstan shaft
1.
Detach the pinch roller from the capstan shaft.
2.
Set the tension gauge by hooking the tension
gauge adapter onto the pinch roller shaft.
3.
Gradually release the pressure to allow the pinch
roller to touch the capstan shaft. When the
pinch roller just touches the capstan shaft, read
the indication on the gauge.
4.
Check that the reading of the tension gauge is in
the range of 900 to
Tension gauge adapter
Figure
l-1 5.
1200 g.
CHECKING AND ADJUSTMENT OF TENSION
POLE POSITION
l
Remove the cassette housing control assembly.
Tension/pole
I
0.2mm
I
Center line
Make the adjustonent with the beginning of a
E-180
tape.
0
If the end is at the left from the center line:
+fw
-+
Figure
l-1 7.
l Make a short-circuit between
TP8805,
on the VCR
turn on the power.
l
Setting
1.
Open the lid of cassette tape (E-180), and hold it
with two pieces of vinyl tapes.
2.
Load the cassette tape into the unit.
3.
Put the weight
4.
Make the adjustment with the beginning of a
E-l 80 tape.
l
Checking
1.
Set a cassette tape, press the
the tape loaded. Now check the tension pole
position.
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
(500g)
on the cassette tape.
Figure
l-16.
TP8804
REC
button and get
and
26
Figure
l-18.
1.
Remove the cassette and press the
make an empty loading. Put a bladed
screwdriver into the tension band positioning
cam and turn it clockwise.
2.
Place the cassette in position and check the
tension pole position.
@
If the end is at the right from the dotted line:
I
@
4
Figure l-l
1.
Remove the cassette and press the
make an empty loading. Put a bladed
screwdriver into the tension band positioning
cam to turn it counterclockwise.
2.
Place the cassette in position and check the
tension pole position.
.
i
I
0
1
I
0.2mm
I
L-1
9.
REC
button to
REC
button to
Note:
@The tension band positioning cam cannot be
adjusted with a cassette in place because the cam
will be located below the cassette. Repeat a
series of steps; empty loading, adjustment,
cassette placement and position checking.
aTurn
@Adjustable range of the tension pole positioning
the positioning cam clockwise to move the
tension pole to the right (in the black-arrow
direction). Turn it counterclockwise to move the
tension pole to the left (in the white-arrow
direction).
Figure
l-20.
cam.
Tension arm shaft
\
arm
VT-3428X
VT-51 28X
w
Figure
l-22.
l
Checking
1.
Push the
REC
button to place the unit in the
record mode.
2.
Check that the back tension indicated by the
gauge is within the set range 31 to 38 g-cm.
Notes:
1.
Make sure that the video cassette tape is over
the retaining guide.
2.
Make sure that the tape is not slack nor
damaged at either end.
0
Adjustment
1.
If the reading of the cassette torque meter is less
than specified, move the tension spring hook
toward A.
2.
If the reading of the cassette torque meter is
more than specified, move the tension spring
hook toward
B.
meter
Tension pole adjusting cam
Figure
l-21.
Adjust the tension pole positioning cam so that the
arrow mark on the cam be within
90”
left and right
from the tension arm shaft’s center.
CHECKING AND ADJUSTMENT OF
RECORD / PLAYBACK BACK TENSION
l
Remove the cassette housing control assembly.
l Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. NOW
turn on the power.
l
Setting
1.
Open the lid of the cassette torque meter, and
hold it with two pieces of vinyl tapes.
2.
Load the cassette torque meter into the unit.
3.
Put the weight (5009) on the cassette torque
meter.
TP8804
and
Figure
ping
l-23.
27
m-3428X
VT-5128X
I
1
CHECKING THE BRAKE TORQUE
l
Checking the brake torque at the supply side
,
Supply reel disk
5-l
5mN.m (SO-1
lo-50mN.m (102-SlOgf-cm)
Figure
l
Remove the cassette housing control assembly.
SOgf-cm)
l-24.
l
Checki4the brake torque at the take-up
CCW: lo-50mN.m (102-510gfxm)
CW:
5-l
5mN.m (SO-1
Figure
l
Remove the cassette housing control assembly.
SOgf-cm)
l-25.
side
l Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
TP8804
and
turn on the power.
0
Setting
1.
Set a torque
on the supply reel disk.
2.
Switch from the FF mode to the STOP mode.
3.
Disconnect the AC power plug.
l
Checking
1.
Slowly rotate the torque gauge in the clockwise
(CW)
direction and counterclockwise
direction of the supply brake so that the reel disk
and the indicator of the torque gauge rotate at
an equal rate. Check that the values are within
the range of CW direction =
(102-510gfcm), CCW
(50450gfcm),
CW
direction is at least twice as high as that in
the
CCW
gauge to zero on the scale. Place it
IO-50mN.m
direction =
and that the brake torque in the
direction.
545mN*m
(CCW)
l Make a short-circuit between
TP8805,
on the VCR
both located at the center on your side
PWB,
with a 22 ohm resistor. Now
TP8804
and
turn on the power.
0
Setting
1.
Set a torque gauge to zero on the scale. Place it
on the take-up reel disk.
2.
Switch from the FF mode to the STOP mode.
3.
Disconnect the AC power plug.
l
Checking
1.
Slowly rotate the torque gauge in the clockwise
(CW)
direction and counterclockwise
direction of the take-up brake so that the reel
disk and the indicator of the torque gauge
rotate at an equal rate. Check that the values
are within the range of
IO-50mN.m
545mN*m (50450gfcm),
torque in the
high as that in the
l
Adjustment of the brake torque at the supply
(102~510gfcm), CW
CCW
direction is at least twice as
CVV
direction.
CCW
direction=
direction =
and that the brake
(CCW)
side and the take-up side
1.
If the supply or take-up brake torque is outside
the range, clean the supply or take-up reel disk
break lever pad, then recheck the torque.
2.
If the supply or take-up brake torque is still
outside the range, replace the main brake
or the main brake spring.
Note:
When the main brake is replaced, perform the
height checking and adjustment of reel disks (see
page
22),
and the brake torque checking.
ass’y
28
VT-3428X
VT-51 28X
REPLACEMENT OF A/C (Audio/Control)
HEAD
1.
Remove the cassette housing control assembly.
2.
Place the unit in the unloading mode, and
unplug the power cord.
l
Removal
1.
Loosen the tilt adjusting screw
2.
Remove the azimuth adjusting screw
3.
Remove the AK head screw
4.
Unsolder the A/C head PWB soldered to the A/C
0.
a.
0.
Figure
head assembly.
Notes:
1.
After replacement, be sure to perform the
adjustment of the tape drive train (see page
33).
Under any circumstances, avoid touching the
head. Clean the head, if touched with your
finger, with alcohol.
2.
Take care that the azimuth spring does not fly
1
off when removing the A/C head screw.
l
Adjustment
[A/C
head tilt angle]
1.
Set the mechanism to the loading mode.
2.
Place the A/C head tilt adjusting Jig
3.
Slowly turn the tilt adjusting screw Q with a
screw driver until there is no gap between the Jig
and the AK head.
A piece of white paper
_
(fqr
visuality of a gap)
adjusting nut
l-28.
0.
A/C head
Pay attention to
l
Replacement
1.
Solder the removed A/C head
AK
head assembly.
2.
The A/C head assembly is attached so that the
-
Figure
l-26.
PWB
onto a new
PCB
A/C head arm and A/C head plate are roughly
parallel to each other.
PCB
A/C head
New
A/C head tilt
adjusting jig
AK
head arm
Tilt adjusting
screw
Screw driver
A/C
J
Figure
head
(W
l-29.
Never
touch the
Figure
\
A/C head plate
l-27.
29
VT-3428X
VT-51 28X
[A/C head height rough adjustment]
l
Setting
1 k
Box driver
Figure
l-30.
HEIGHT ADJUSTMENT OF REVERSE GUIDE
[Height adjustment of reverse guide]
Reverse guide height
adjusti?g jig
guide
Reverse guide height
adjusting jig
Go-end is
mm. Not go-end
is
13.38
13.52
mm
4-f
(a)
Figure
l-33.
1.
Remove open lever (Figure
In the tape load mode, make adjustment at the
2.
13.38mm
adjusting nut by
Actually load the unit with a tape, put it in the
3.
play mode, and make sure the tape is free from
wrinkles near the reverse guide.
4.
Use a commercially available box driver to turn
the height adjusting nut.
side first and then rotate the height
l/6
turn counterclockwise.
l-34.
W
(a))
:hassis
Figure
l-31.
aRoughly
turning the A/C head adjusting hexagon nut
with the specialized box driver until the tape is in
the position shown below.
@Set the cassette tape to the mechanism chassis.
@ Press the PLAY button to the put the unit in the
playback
0
Adjustment
Adjust the nut visually so that the control head is
visible
adjust the height of the A/C head by
mode.
Figure
l-32.
0.3
to
0.5mm
below the bottom of the tape.
Box driver
Q
Height adjusting nut
30
Figure
l-34.
Loading...