Sharp VC-780E User manual

VC-790ET
SHARP
SERVICE
MANUAL
|
S29X6VC-780E/
|
VIDEO
CASSETTE
RECORDER
VC-780E
moves
VC-790ET
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.
CONTENTS
SPECIFICATIONS
DISASSEMBLY
AND
REASSEMBLY
LOCATION
OF
MECHANICAL
PARTS
ADJUSTMENT,
REPLACEMENT,
ASSEMBLING
AND
|
TOOLS
NECESSARY
FOR
MECHANICAL
ADJUSTMENT
ADJUSTMENT
OF
ELECTRICAL
CIRCUITRY
TROUBLESHOOTING
GUIDE
OTHER
TROUBLESHOOTING
GUIDE
WAVE FORMS
OVERALL
SEHEMATIC
DIAGRAM
SCHEMATIC DIAGRAMS
WIRING SIDE PWBs
REPLACEMENT PARTS LIST
EXPLODE VIEWS
PACKING OF THE SET
femmes ge ees, Aes
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SHARP
CORPORATION
a

=
in
VC-790ET
Format:
Video recording system:
Video signal: PAL:
PAL:
PAL:
SECAM:
SECAM:
SECAM:
NTSC:
. NTSC:
Recording playing time:
Tape width:
Tape speed:
Antenna:
-Receiving channel:
RF converter output signal:
Power requirement:
Power consumption:
Operating temperture:
Storage temperature:
Weight:
Dimensions:
VIDEO
Input:
Output:
AUDIO
Input:
Output:
AUDIO
Input:
Output:
Accessories included:
Note:
SPECIFICATIONS
VHS standard
Rotary
two-head
helical
scan
system
with
slant
double-azimuth
combination
video
head.
PAL System-B/G ( P.B/REC)
PAL System-| (P.B/REC)
PAL System-D (P.B/REC)
MESECAM System (P.B/REC)
SECAM System-B/G ( P.B/REC )
SECAM System-D/K ( P.B/REC )
NTSC 4.43 ( P.B/REC)
_ NTSC 3.58 ( P.B/REC)
240
min
max.with
SHARP
E-240
tape
(PAL/MESECAM/SECAM
in
SP
mode)
8
hours
max.
with
SHARP
E-240
tape
(PAL/MESECAM/SECAM
in
LP
mode)
160
min
max.with
SHARP
T-160
tape
(NTSC
in
SP
mode)
320
min
max.with
SHARP
T-160
tape
(NTSC
in
LP
mode)
8
hours
max.
with
SHARP
T-160
tape
(NTSC
in
EP
mode)
12.7 mm
23.39
mmisec.
(PALin
SP
mode)
33.35mm/msec.
(NTSC
in
SP
mode)
11.7mmisec.
(PALinLP
mode)
16.68mmi/sec.
(NTSC
in
LP
made)
11.12
mm/sec.
(NTSC
in
EP
made)
75 ohm unbalanced
VHF E2~ E12, (44.25MHz ~294.25MHz)
UHF E21~ E69, (471.25MHz ~885.25MHz)
UHF
Channel!
E30
~
£39
(adjustable).
Preset
to
Channel
E36
UHF
Channel
US26~US38(adjustable).
Preset
to
Channe!
US34
UHF
Channel
J25~J37
(adjustable).
Preset
to
Channel
J33
AC 100~240V, AUTO 50/60 Hz
Approx. 23W (at AC 220V 50Hz)
5°C to 40°C
- 20°C to 55°C
5.8kg
430 mm (W) x 350 mm (D) x 89mm (H)
1.0 Vp-p, 75 ohm
1.0 Vp-p, 75 ohm
OdB = 0.775 Vrms
Line: -8dB,
more
than
50k
ohm
at
RCA
terminal
Line:
-
5
dB,
less
than
1k
ohm
0d8 = 0.775 Vrms
Line:
-
3.8
dB,
more
than
50k
ohm
\
at
Pin
21
terminal
Line:
-
3.8
dB,
less
than
1k
ohm
Antenna
75
ohm
coaxial
connector
cable
(plug
provided)
Operation
Manual
infrared Remote contro!
As
part
of
our
policy
of
continuous
improvement,
we
reserve
the
right
to
alter
design
and
specifications
without
notice.
The
antenna
must
correspond
to
the
new
standard
DIN
45325
(IEC
169
-
2)
for
combined
UHF/VHF
antenna
with
75
ohm
connector.

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rs
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a
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PS Po
DISASSEMBLY AND REASSEMBLY
Remove the four upper cabinet fastening screws q).
Remove the six bottom pane! fastening screws @).
Remove the one front panel fastening screw (3).
Release the three clips (4) and remove the front panel.
Remove the two antenna terminal cover fastening screws
on the tow push rivets which fasten the syscon servo
unit and the angle.
Remove the four syscon servo unit fastening screws (7) F
Remove the Y/C PWB holder @).
9, Remove the two main PWB fastening screws (9) ‘
. Remove the two head amp PWB fastening screws ;
. Remove the three power unit fastening screws
. Remove the four machanism chassis fastening screws
Release the timer PWB 43) fastening clips.
Release the operation PWB fastening clips.
Vi- #00)
VC-790ET
a

LOCATION.
LIST
OF
MECHANICAL
PARTS
|
A/C
head
arm
-
os
Half-loading
lever
spring
.
inch roller lever ass’y
elay shifter lever
etaining guide |
Capstan 0.D.motor
Main
take-up
brake
lever
eee
ee:
Cassette
LED
-
Reverse
guide
spring
@
nghrl
sere
bee
aeetcitl
7
Idler
gear
ass
y
Take-up
reel
disk
.
Reverse guide
|Video search brake lever
7 |Take-up pole base slider
Tension spring hook plate - .
— LL
Half-loading lever
Reel pulley
Reel sensor PWB
Brake solenoid
Shifter spring
Shifter spring cover .
ut
Connector
Tension band ass’y
17 | Auxiliary fast forward brake lever
Reverse guide spring
Reel belt
Loading relay gear
> an : WwW
Supply pole base ass’y ;
5
wi nn
Slow brake fever
ee
X-position adjusting nut
Half-loading reciprocating spring
Half-loading reciprocating lever
Slow brake spring
ive)
Relay gear drive lever ~
Take-up loading gear
NS
Take-up loading armass'y —.
Drum D.D. motorass'y __
Supply loading gear :
Supply loading arm ass‘y |
Loading reciprocating spring
Supply pole base slider
oS
67 | Reel block chassis
wal uw
~
Auxiliary fast forward brake spring
Full flat cable holder
ull flat cable( Drum D.D. motor)
tat mw
Wi wi Ww as mT NO eed
Ww “wan >
0
3. | Half-loading drive lever
AJ —-
4 }jLoading block ass’y Reel sensor
on Loading
motor
ain
brake
spring
Master
cam
ew
sensor
=
w | w
sls
BE
fj Ww
Oo
>
oy

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LOCATION
OF
MECHANICAL
PARTS
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| VC-790ET
ADJUSTMENT, REPLACEMENT, ASSEMBLY AND
CLEANING OF MECHANICAL UNITS
Here we will describe a relatively simple service work We are sure that the easy-to-handle tools listed
in
the
field,
not
referring
to
the
more
complicated
below
would
be
more
than
handy
for
periodical
repairs
which
would
require
the
use
of
special
maintenance
to
keep
the
machine
in,.its,original
equipment and tools (drum assembly or re- efficient condition.
placement, for example).
TOOLS NECESSARY FOR ADJUSTING THE MECHANICAL UNITS
The following tools are required for proper service and satisfactory repair.
[na[ item | ranno. fou] configuration
Reel Disk Height AdjustingJig.” Ss: Ss SiGRHOOO2 ?
JiGACH-F18
Torque Gauge (90g) JiGTGOOSO
Torque Gauge (1.2 kg) JiGTG1200
5 Gauge Head
Cassette Torque Meter
ne [we
wm [| SA
ae
Hex Wrench (1.5 a
VROCPSV
These Jigs are used for checking and
adjusting the reel disk height.
This Jig is used for settimg the A/C
ASC
Head
Tilt
Adjusting
Jig
eine
ead
tilt.
—
These Jigs are used for checking and
adjusting the torque of take-up and
supply reel disks.
This cassette torque meteriis Used
for checking and adjusting the
torque of take-up and supply reel
and for measuring tape back
tension.
There are two Gauges used for the
tension méasurements, 300 g and
2.0 kg.
6
7
These Jigs are used for loosening or
tightening special Hexagon type
screws.
This tape ts especially used for
electrical fine adjustment.
Alignment Tape (PAL}
This is used for replacement of the
VCR's upper drum.
Drum
Replacing
Jig
JiGDT-0001
This Jig is used for the tension
gauge. Rotary Transtormer
Clearance Adjusting Jig.
JiGADP003 BK GN SB
Tension Gauge Adapter

¥,
VC-790ET
2] aw |
JIGDRIVER-6 a
Torque
Driver
JiGTD1200
JIGDRIVER1 10-7
This Screwdriver is used for
adjusting the guide roller height
and X-position.
Special
Bladed
Screwdriver
JiGDRIVERH-4
This Jig is used for adjusting the
tension band and tension plate.
Tension Band and Plate Adjusting Jig
This is used to screw down resin-
made parts: the specified torque is
5 kg.
This Jig is used for height
adjustment of the A/C head.
Box Driver
This Jig is used for height
adjustment of the retaining guide.
JiGDRIVER1 10-4
” a
JiGRVGH-F1i8 =| BU ar
Current
JiGMA0001
contains
Master
Plane
(JiGMP0001)
and
Disk
Height
Adjusting
Jig
ViGRHO001).
Even
though
new
Disk
Height
Adjusting
Jig
UiGRHO002)
covers
greater
height,
This Jig is used for height
Retaining
Guide
Height
Adjusting
Jig
sdjustient
Gt
the
retaining
guide
This Jig is used for height
adjustment of the reverse guide.
Reverse Guide Height Adjusting Jig
this
new
Jig
JiGRHO002)
can
be
used
for
current
JiGRHO001,
but
current
Jig
(JiGRHO001)
cannot
be
used
as
JiGHROO02.Master
Plane
(JiGMPO001)can
be
used
with
JiGRHO001
and
JiGRHOOO2
as
well.

Vier FOUL
VC-790EF
:
MECHANICAL
PARTS
REQUIRING
PERIODICAL
INSPECTION
~
Use
the
following
table‘as
a
guide
to
maintain
the
mechanical
parts
in-good
operating
condition.
ee
=
nt
Remarks
Abnormal rotation or significant
vibration
requires
replacement.
-.
Clean
with pure
high
quality
—-
~-
isopropy!
alcohol.
conan
tetetete
Cc
i
ee
ROS
Ee
oe
Clean tape contact area with the PS
specified cleaning liquid.
Clean tape contact area with the
specified cleaning liquid.
Clean rubber and rubber contact
area with the specified cleaning
NOTE: ©: Part replacement.
OC):
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).
This
model
has
no
adjusting
parts
for
torques,
tension,
etc.
If
the
reading
is
outside
the
specified
range, clean or replace the part.

REMOVAL
AND
REASSEMBLY
OF
CASSETTE
HOUSING
CONTROL
ASSEMBLY
Notes:
1.
During
removal
and
reassembly,
be
careful
not
to
strike
the
nearby
guide
pin,
drum,
etc.
2:
Before
removal
or
reassembly,
be
sure
to
unplug
the
recorder
from
the
AC
outlet.
3.
When
removing
and
attaching
the
cassette
loading
belt,
be
careful
to
keep
it
free
from
grease.
Removal
_
Put
the
unit
in
the
cassette
eject
position.
_
Remove
the
cassette
loading
belt
©.
Disconnect
the
FFC
(Full
Flat
Cable)
@
at
the
right
side
of
the
cassette
housing
control
assembly.
Note:
Be
careful!
not
to
break
the
FFC.
4.
Remove
the
two
cassette
housing
installation
screws.
_
Move
the
cassette
housing
control
assembly
(Fig.
1-1)
in
the
direction
of
arrow
=>
®,
and
pull
it
out
straight
upward.
wn— @
wi
e® Reassembly
1.
Insert
the
tabs
of
the
cassette
housing
contro!
assembly
into
the
mechanism
chassis,
move
it
in
the
direction
of
arrow
>
@,
and
secure
tem-
porarily.
Check
to
see
if
the
cassette
housing
control
assembly
is
in
the
correct
position,
and
then
tighten
the
two
screws
(XHPS330PO06WSO)
.
_
Attach
the
cassette
loading
belt
©.
|
Connect
the
FFC
@
at
the
right
side
of
the
cassette
housing
control
assembly.
Ww A
(D
Cassette
loading
belt
@ FFC
ball 1
—
bed For
~
HM
—
1
=f
HELE +
i
Insert
the
tabs
of
the
cassette
housing
into
the
GL,
mechanism
chassis.
Figure 1-1.
(Full flat cable}
V¥U- 760
VC-790ET
REPLACEMENT
OF
WORM
WHEEL
ASSEMBLY
e
Removal
(Fig.
1
-
2)
1.
Unsolder
the
cassette
switch
connector
from
the
start
sensor
PWB
@
2?
Release
the
two
catches
@on
the
cassette
housing
frame
(R),
and
remove
the
PWB.
3.
Unscrew
one
B
tight
screw
@
to
detach
the
worm
bracket
@.
Note:
The
bearing
@
can
come
off
position
too.
So
be
careful
not
to
let
the
bearing
fall.
4.
Remove
the
worm
shaft
assembly
©,
pulley
©
and
cassette
loading
belt
@
all
from
the
cassette
housing
frame
(R).
5.
Finally
pull
the
worm
wheel
assembly
out
of
the
boss
of
the
cassette
housing
frame
(R).
e
Reassembly
(Fig.
1-2)
1.
Turn
the
phase
gear
@
clockwise
until
the
slider
comes
to
a
halt
in
the
cassette
insertion
direction.
2.
Set
up
the
worm
wheel
gear
assembly
onto
the
boss
on
the
cassette
housing
frame
(R),
matching
the
mark
©
on
the
phase
gear
@
with
the
mark
®
on
the
worm
wheel
gear.
Note:
Make
sure
that
the
slider
pin
is
in
the
groove
of
the
drive
gear
arm.
3.
Install!
the
pulley
©
and
apply
the
cassette
loading
belt
@
both
on
the
worm
shaft
assembly
©.
Couple
the
clutch
@
to
the
clutch
lever
©.
|
And
mount
them
together
in
the
cassette
housing
frame
(R)
.
4.
Attach
the
worm
bracket
@
to
the
worm
shaft
assembly
@.
Place
them
onto
the
boss
on the
cassette
housing
frame
(R).
5.
Tighten
one
B
tight
screw
@.
Note:
Make
sure
that
the
parts
©
and
©
of
the
cassette
housing
frame
(R)
are
properly
engaged
with
the
parts
©
and
©
of
the
worm
bracket
@.
6.
Hook
the
start
sensor
PWB®@
on
the
two
positions
®
on
the
cassette
housing
frame
(R).
Note:
Check
that
the
switch
connector
is
right
in
the
cassette
switch
mounting
hole
©.
7.
Finally
resolder
the
cassette
switch
connector
to
the
start
sensor
PWB.
Notes:
1.
Do
not
overtighten
the
B
tight
screw
(no
more
than
5.0+0.5
kg.
cm),
because
otherwise
the
lower
threads
of
the
screw
hole
at
the
resin-
made
boss
may
be
broken.
2.
Keep
in
mind
that
the
clutch
switching
lever
should
be
in
the
correct
positional
relation.
The
mechanism
might
malfunction
even
if
the
lever
‘comes
slightly
out
of
position.

Vie OV
\ VC-790ET
Figure 1-2 {a).
Cassette housing frame (R)
“
Sie
Connector
op
@
é
2
x
8)
Pulley
‘Le
:
wS
sigs
|
“DY
Sarg
e
2h
“RAY
SN
at
~.
nae
;
.
4
Clutch
PS
a
“i
wr
é
5)
Worm
shaft
ass‘y
ee
x
(8)
Cassette
SW
eee
mounting
hole
Mes
(1)
Start
sensor
PWB
~
s
©)
a.
>
>
2)
Drive
gear
arm
~
;
ee
a
groove
@)
Bearing
|
ot,
(3)
Worm
bracket
(2) B tight screw
{LX-HZ3046GEFD)
Worm wheel gear
8) Phase gear
Figure 1-2 (b).
@ Reassembly of drive gear (Fig.1- 3)
1. Pass the tip of the drive gear spring (R} @
through the square hole @ of the drive gear (R)
@ to the hook the spring in position.
2. Hook one end © of the reciprocating spring @
to the catch © of the drive gear (R) @.
3. Hook the other end © of the reciprocating
spring @ to the catch © of the worm wheel @.
4. Fit the drive gear (R) M to the worm wheel @ so
that the catch @ and boss @ on the drive gear
(R) are exactly in the square hole @ and round
hole (, Respectively, in the worm wheel.
(1) Drive gear {R}
2 Drive gear spring (R) /.
REPLACEMENT OF CASSETTE LOADING _
BELT
® Replacement (Fig. 1-4)
1. Remove the start sensor PWB and worm bracket
from the cassette housing frame (R).
2: Remove the worm shaft assembly, pulley and
cassette loading belt from the cassette housing
frame (R). .
3. Replace the cassette loading belt with a new
one.
Notes:
1. Do not overtighten the B tight screw which holds
the worm bracket in position. The specified
tightening torque is 5.0 + 0.5kg. cm.
2. Make sure that the cassette loading belt, being
applied in the cassette housing frame (R), is free
from grease. if stained with grease, clean the belt
with the specific cleaning liquid.
3. Finally check the clutch switching lever for its
specified points.
Cassette loading belt
Worm shaft ass‘y
Figure 1-4.