Salora SV8720 User manual

SALORA
HUOLTO -SERVICE
SERVICE-MANUAL
VIDEO TAPE RECORDER SV8720
Tape Format
Power Source
Power
Consumption
Television System
Video Recording
System
Luminance
Colour Signal
Audio Track
Tape Speed
Record/Playback
Time
Heads: Video
Audio/
Control
Erase
ZB1276 09.87 .
| VHS | Only cassettes marked VHS can be used with this video cassette recorder.
SPECIFICATIONS
: VHS 1/2" high-density video
cassette tape
: 220V AC; 50Hz
. Approx. 23W
: PAL colour and CCIR
monochrom signal (System B &
G) 625 lines, 50 fields
: 4rotary heads, azimuth helical
scanning system
: Frequency modulaticn
recording
: Low frequency conversion
sub-carrier phase shift
recording
> 1 track
: 23.39 mm/sec (Standard Play)
: 11.7 mm/sec (Long Play)
: 240 min. with E-240 cassette
(Standard Play Mode)
: 480 min with E-240 cassette
(Long Play Mode)
: 4rotary single crystal heads
: 1 stationary head
: 1 full track head
Video Input
Audio Input: Line
Video Output
Audio Output
TV Tuner
Operating
Temperature
RF Channel Output
Weight
Dimensions
Timer
Channel Selection
: 0.7510 1.5 Vp-p, ohm
unbalanced Scart sc ket
- —8dBs, 50K ohmin balanced
Scart socket
:
1.0Vp-p,
75
ohm
wp
alanced
Scart socket
: —8dBs, 1K ohm up @lanced
Scart socket
> VHF 2~12CH
UHF 21 ~69CH
CATVS1‘ ~ $3’, Si1— S20
> BC to 40°C
: Set to Channel 36
Channel 32 — Chan €! 40
Selectable
: Approx. 5.8 kg
- 424 mm (W) x 92 ne {H)
x 310 mm (D)
- 7 programs for anyckannels in
two weeks/every ay” _
1 program for any nzenneis In
every week day
24 hour digital synh a Onized with
crystal oscillator friq #eNcy.
- 30 position UP/DOY ™N
(Voltage synthesize =selector)

CONTENTS
Disassembly
...............0::::ccccecsceereettteetnneeees
1
How
to
execute
Circuit
Board
service
..........
2
Cleaning
oo...
ec
eecee
eter
ere
tee
eee
eteertettaes
4
Mechanical
&
Electrical
Adjustment
TOOISS
oo
efxkcehiie
ee
eee
5
Major
component
removal
and
installation
...................00-:c
eee
f)
4-1
Picture
Control
Adjustment
...................55
7
1-2
Still
Adjustment
20...
ee
7
2.
Removal/Replacement
of
Primary
Parts
..0.0...0..0000
cee
eee
7
2-1
Replacement
of
Cassette
Housing
............
7
2-2
Replacement
of
Drum
Motor/Video
Head
ASSEMDIY
........eccceceeeceeeteteteettees
8
2-3
Replacement
of
Upper
Drum
.............
Ss)
2-4
Replacement
of
Capstan
Motor
..............5
9
2-5
Replacement
of
Belt
Ro...
ee
10
2-6
Replacement
of
Loading
Motor
..............-5
10
2-7
Replacement
of
Pinch
Roller
..............
10
.
Electrical
Adjustments
.................
ee
11
3-1
Servo
Circuit
Adjustments
............
ee
12
3-2
Y/C
Signal
Circuit
Adjustments
..............-
12
3-3.
Audio
Circuit
Adjustments
...............
ee
14
ne
4.
Mechanical
Adjustments
................0.....:.:05
15
4-1
Tension
Pole
Position
Adjustments
............
15
4-2
Installation
of
Master
Plane
Jig
.............0.
15
4-3. Supply Impedance Roller and Take-up
Guide Pole Height Check and
ACJUSTMENE ...c sed seetinnnea taney aes 15
4-4 Reel Disc Height Check and
AGJUStMONT cas cise anaes sas 16
4-5 Arm Take-up Guide Pole Height
AdjUStMENE oo... eee ee eee rete eres 16
4-6 Back Tension Check and
ACjUStMENt oo... eee cette teeter 16
4-7 Positioning of Gears and their
Installation SEQUENCE ....... ee cee 17
4-8 Mode Switch Attachment and
AdjUStMENE
oo...
eee
cece
eect
eeteeteeneees
17
4-9
Half
Loading
Unit
Adjustment
..............05
18
4-10
Tape
Path
Check
and
Adjustmen:
.
............
me)
4-11
Interchangeability
Adjustments
...
0.0.0...
.,
KEY
TO
ABBREVIATIONS
.................
-.005
25
Parts:
List
.
3c
canes
seoniec
eels
26
1.
CABINET
ASSEMBLY
..........c
ce
crete
26
2.
DECK
ASSEMBLY
0.0...
cceeecceeee
eee
etteeenees
27
3.
ELECTRICAL
PARTS
.0.....
ccc
eccceccuce
ceteris
31
4.
PACKING
PARTS.
.......ccccccceeeeeeeeenee
tetreeetenes
34
Circuit Diagrams
cee

DISASSEMBLY
1.
REMOVAL
OF
TOP
COVER
A.
As shown in Figure 1, remove the four screws
®. ©. © and ©), two on each side, retaining
the top cover.
Gently expand the bottom edges of the top
cover, pivot cover forward, then slide toward
rear, in the direction of the arrows.
2. REMOVAL OF FRONT PANEL
A.
B.
Remove screw at @.
Unfasten the seven snaps (©), ©. ©. ©. ©. ©
and @) and remove the front panel in the
direction shown by the arrows.
3. REMOVAL OF BOTTOM COVER
A. Remove the seven screws (©, ©, ©. O. ©. ©.
and @) retaining the bottom cover as shown in
Fig. 3.
. Remove the bottom cover by sliding toward the
rear side and pulling outward in the direction of
the arrow.

HOW
TO
EXECUTE
CIRCUIT
BOARD
SERVICE
CAUTION: BEFORE ATTEMPTING TO RE-
MOVE OR REPAIR ANY PCB
UNPLUG THE POWER CORD
FROM THE A.C SOURCE BES SIONS!
Location of Printed Circuit Boards (Refer to Fig. 4)
PCB-TIMER
PCB-OPE
1. PCB SIGNAL
A. Remove 4 retaining screws on the top side (@,
®,. © and ©) and 2 retaining screws (© and ©)
on the rear side of the signal circuit board,
which is shown in Fig. 5.
B. Open the circuit board in the arrow marked
direction, letting the right side hook hang on the
base chassis.
2. PCB CONTROL/POWER
A. Remove the signal circuit board which is given
in Item (1).
B. Remove the bottom cover, (Refer to Item (3) on
page 1).
In general, under the circumstances, the ser-
vice of the control circuit board will be available.
C. Removing two retaining screws (© and ©)
which are shown in Fig. 6, raise up and remove
the circuit board.
PCB-SIGNAL

3.
PCB
OPE
A.
Unlock
the
PCB
Ope
Supporter
@,
as
shown
in
Fig.
7.
B.
Remove
the
PCB
Ope.
Supporter @
4. PCB TIMER
A.
Unlock
the
two
PCB
Timer
Supporters
(@
and
®) as shown in Fig. 8.
B.
Remove
the
PCB
Timer.
5. PCB Power SUB
A.
Remove
the
three
screws
(@,
and
©)
retaining
the
PCB
power
sub
as
shown
in
Fig.
9.
B.
Remove
the
screw
©
retaining
the
Cover
Power as shown in Fig. 9.

CLEANING
The following items require cleaning after servicing to
maintain satisfactory performance.
1. VIDEO HEAD CLEANING
A.
B.
C.
Remove the top cover. (Refer to item 1 on page
1)
Remove the Stay-Stopper-C. (Refer to item
2-1-1 C on page 7)
Moisten a clean piece of chamois with a
professional head cleaning solution. Hold the
chamois to the drum assembly and rotate the
drum clockwise by hand to clean the video
heads and tape path.
NOTE:
Never move the chamois vertically while clean-
ing, otherwise the heads will be damaged.
After the heads are cleaned, allow the cleaned
portion to dry thoroughly before running a tape,
otherwise the tape and head may be damaged.
2. TRANSPORT SYSTEM
(The transport mechanism should be cleaned after
every 500 hours of use to maintain proper operation.)
A. The following components of the transport
system require occasional cleaning:
© S.SLANT POLE
© S.GUIDE ROLLER
@® FE HEAD
@ S.IMPEDANCE-ROLLER
A D ‘
Gj
@ TENSION POLE fe . ZZ
@ sP-GuDE fq
OLE q
“4
@ UPPER & LOWER DRUM
@
TENSION
POLE
@FE
HEAD
@
SP-GUIDE
POLE
@
S.IMPEDANCE-
ROLLER
®©S.GUIDE ROLLER ©S.SLANT POLE
@ UPPER & LOWER = @T.U SLANT POLE
DRUM
©®T.U. GUIDE ROLLER @ A/C HEAD
@T.U.GUIDE POLE @CAPSTAN SHAFT
@ PINCH ROLLER SHAFT-TU-GUIDE
To clean, use a small piece of gauze moistened
with alcohol.
Use extreme care when cleaning the video
heads and Drum assembly to prevent damage.
Avoid touching the Drum assembly with your
fingers which would deposit skin oil on it.
NEVER clean the Drum assembly by moving
the cleaning pad vertically.
. After cleaning transport mechanism, allow it to
dry thoroughly before loading a tape. /f this is
not done damage to the heads or tape may
result.
3. REEL DRIVE SYSTEM
A. Reel Disc Brake Surfaces require occasional
cleaning using a small piece of gauze mois-
tened with alcohol.
T.U SLANT POLE
© T.U. GUIDE ROLLER
A/C HEAD
@ T.U. GUIDE POLE
@ CAPSTANSHAFT

MECHANICAL
&
ELECTRICAL
ADJUSTMENT
TOOLS
PURPOSE
METHOD
|
Adjustment
Driver
(859C25900)
Fa a i sia
The
adjustment
driver
is
intended
to
adjust
variable
resistors,
trimmers,
transformers
etc.
in the circuitry.
Select
a
tip
suitable
for
the
particular
head
of
the
component
concerned
and
adjust.
Dummy Cassette
and soak-testing.
The
dummy
cover
masks
the
start
and
end
sensors
and
turns
the
cassette
switch
on.
(859C34702)
=
dummy
cover
is
loaded
instead
of
the
cassette
tape
in
repair,
inspection,
adjustment
Load
the
dummy
cover
in
the
cassette
housing
instead
of
the
cassette
tape.
|
Hex Keys (1.5mm)
.*
(859C25902) (859C25905)
Alignment Tape (MH-2 PAL) (59C33901)
The
hex
keys
are
used
for
tightening
or
remov-
ing
hexagonal
socket
head
screws
which
fasten
the
guide
rollers
of
the
supply
and
take-up.
Standard signals (VHS Standard) are recorded
on the alignment tape and reproduced when
required in the adjustment of Y/C circuit, audio
circuit and interchangeability alignment.
and turn.
ordinary tape.
u
Insert
the
given
size
(1.5mm)
hexagonal
socket
Install
and
run
in
the
play
mode,
the
same
as
for
_
Back Tension Gauge (859C34508)
The back tension gauge is used for measuring
the tension of the tape on the supply side.
Load
this
gauge
in
the
cassette
fhousing
and
run
in
the
play
mode.
Read
the
gauge
indicator.
(859C34500)
(859C34501) |
The torque meter is used for measuring the
torque of the reel disc brake, “FF” and “REW”,
Take-up etc.
+.
on the reel disc.
Measure
the
“FF”
and
“REW”
take-up
torque
by
rotating
the
meter
at
the
Same
speed
by
hand
and
reading
the
scale
indicator.
Measure
the
brake
torque
by
setting
the
meter
~

PURPOSE
METHOD
Master Plan Jig
(859C34107)
The height gauge and the master plane are used
for measuring height and perpendicularity of the
heads, rollers, reel discs, etc. of the tape path.
The master plane ts set on the main deck and
the height gauge is applied to the part being
measured.
|
y
|
|
|
|
|
Grip ring fixer
(859C34705)
A tool for preventing the grip ring from opening
excessively.
|
While opening the grip ring with the tips of this
tool, install the grip ring on to the shaft.
a
REC Current Adjustment Jig
(859C34706)
ay
The REC Current Adjustment Jig is use for FM
record level adjustment and Recording colour
level adjustment.
{
Use in conjunction with oscilloscope. For deteil |
refer to the service manual.

MAJOR
COMPONENT
REMOVAL
AND
INSTALLATION
1-1
PICTURE
CONTROL
ADJUSTMENT
VCR
picture
quality
may
be
adjusted
according
to
personal
preference:
Rotate
the
picture
control
knob,
located
as
shown
in
Fig.
1,
to
achieve
the
desired
picture
quality.
1-2
STILL
ADJUSTMENT
There
are
some
cases
where
the
picture
bounces
vertically
in
the
STILL
mode
when
VIDEO
CASSETTE
was
recorded
on
another
VCR.
In
such
a
case,
adjust
the
still
knob,
located
as
shown
in
Fig.
1,
until
bouncing
stops.
2.
REMOVAL
OF
PRIMARY
PARTS
2-1
Replacement
of
Cassette
Housing
2-1-1
Removal
A.
Remove
the
Top
Cover
and
Front
Panel.
B.
Place
the
PCB
signal
vertically
in
the
service
position.
C.
Remove
the
screw
@
retaining
the
Stay
Stop-
per
C,
as
shown
in
Fig.
2-1(A).
D.
Remove
the
Stay
Stopper
C.
—£.
Remove
the
two
screws
(@)
and
©)
retaining
the
Stay
front
as
shown
in
Fig.
2-1(A).
F. Remove the Stay front.
G.
Remove
the
Cassette
Housing
loading
belt
as
shown
in
Fig.
2-1(B).
H.
Disconnect
connector
[CT],
as
shown
in
Fig.
2-1(C).
Remove
the
two
screws
(®
and
@®)
retaining
the
Cassette
Housing
as
shown
in
Fig.
2-1(C).
J.
Remove
the
Cassette
Housing
by
sliding
back
in
the
direction
of
the
arrow.
STILL ADJ
PICTURE CONTROL
Fig. 1
Cassette Housing loading belt
Fig. 2-1(B)
Connector
Fig. 2-1(C)

2-1-2 Replacement
To
reassemble
the
cassette
housing
into
the
VCR
adhere
to
the
following
steps.
If
these
steps
are
not
carried
out
properly,
abnormal
noise
may
be
produced
in
the
FF
and
REW
modes
or
the
tape
may
be
damaged
in
playback.
A.
Place
the
PCB
Signal
vertically
in
the
service
position.
B.
Set
the
positioning
U-holes
at
the
right
and
left
front
of
the
cassette
housing
sides
onto
the
pins
at
the
front
side
of
the
main
transport
plate,
refer
to
Fig.
2-1(C),
then
slide
the
cassette
housing
inside
to
the
point
where
the
holes
for
the
housing
screws
are
matched
to
the
screw
holes
on
the
main
plate.
Install the two cassette housing screws.
Reconnect connector
Attach the cassette housing loading belt shown
in Fig. 2-1(B).
F.
Attach
the
stay
front
as
shown
in
Fig.
2-1(A).
G.
Attach
the
Stay
Stopper
C
as
shown
in
Fig.
2-1(A).
H.
Check
that
the
cassette
is
loaded
and
unloaded
smoothly
without
abnormal
noise.
|. Check that, in the unloaded position, the loading
prevention latch attached to the bottom of the
cassette housing is fastened to the housing
side strip. (See Fig. 2-1 (D))
J.
If
an
irregularity
is
detected
in
steps
(H)
and
(I)
the
cassette
housing
may
be
incorrectly
assem-
bled.
Loosen the fastening screws, unfasten the
cassette housing and readjust, as required.
moo
Loading prevention latch
Fig. 2-1(D)
2-2 Replacement of Drum Motor/Video Head
Assembly
2-2-1 Removal of Drum Motor/Video Head
Assembly
Remove the Bottom Cover.
Remove the Stay Stopper C.
Remove the Regulator Transistor fastening
screw as shown in Fig. 2-2(A) and remove the
Regulator Transistor.
D. Remove the three drum retaining screws as
shown in Fig. 2-2(B).
E. Holding the upper drum assembly, remove the
complete Drum Motor/Video head assembly by
gently pulling in an upward direction.
F. Disconnect connectors [DA]and from Drum
assembly.
Cro
Fig. 2-2(A)
Fig. 2-2(B)
2-2-2 Installation of Drum Motor/Video H ead
Assembly
During installation, avoid holding the upper drum with
bare hands. If this cannot be avoided, a cleaning
procedure must be performed as described in ”Clean-
ing” section, on page 4, upon completion of installa-
tion.
A. Reconnect connectors [DA] and
B. Carefully holding the complete drum assembly
(with a piece of cotton cloth), slowly #nsert the
drum assembly into its original drum snounting
position.
Note:
Do not apply excessive force to the vid €0 heads
as damage will result.