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Mechanical Adjustments
Cont'd
Note:
+ There is a long mark at the position of 7.5 mm
_ from the round surface of the mechanical
deck. Make sure the position of the mark
when adjusting.
Tension lever
_"" assembly (2)
Long
$ reel table
mark
assembty (1)
Fig. 7-1-1
1-7-2. Reel Torque Check
{1} Reel torque
1. REVIEW mode (supply side)
Poor torque may not wind the tape. On the
other hand, excessive torque will cause
damage to the tape during REVIEW mode.
2. Record/Playback mode (take-up side)
Too little torque does not rewind the tape to
the end. If too large torque, the tape may be
stretched by excessive tension.
3. Inspection
Rewind the torque cassette to the end, then
check the torque values shown below:
Review
15.95 + 3.65 mNem
(162.5 + 37.5 gecm)
Record/Playback
6.85+2.45 mN*m
(70 + 25 gecm)
For checking method, refer to the following
item (2).
(2) Reel torque and back tension check
1. First, record a TV broadcast program on the
entire torque cassette tape (KT-300NR} in the
SP mode.
2. Load the torque cassette tape (KT-300NR) in
the VTR and feed it forward until the end of
the tape, before proceeding with measure-
ment.
3. Set the VTR to the REVIEW mode and feed
the tape for about | 5s, and then make sure
the take-up torque described above is
obtained while observing the left torque
meter.
4. After compietion of step 3), feed forward to
tape start position and set the VTR to the
PLAY mode and feed the tape for about 30s.
Read the right torque meter and check the
torque described above is obtained.
5. if the review torque and playback torque are
out of limit, replace the clutch assembly.
6. When the S reel table assembly, the T reel
table assembly and the idle arm assembly are
replaced, perform the reel! torque check.
a
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< Precautions for Use of Torque Cassette
(KT-300NR) >
1. Before loading a torque cassette in a VTR,
always remove tape slack. The tape slack can
be removed
by rotating the reel to its take-up
direction. {The tape tends to slack when there
is no reel brake actions.)
2. When the torque cassette is loaded, confirm
followings:
* Make sure the tape does not ride up or over
the No. 8 cap. If it does, do not eject the tape
but retum the tape to its correct position,
taking care not to damage the tape.
* Make sure the tape is not slackened. tf
siackened, operate the VTR in FF or REW
mode and then stop the tape. Then make
sure the tape is not slackened again.
* After above confirmation, proceed to the reel
torque adjustment and confirmation.
Caution for removal of torque cassette
When removing the torque cassette from the
VTR, set the VTR to the STOP mode and wait
for several seconds. Then, make sure the
tape is not slackened. Push the EJECT button
to remove the cassette.
4. If the previous precautions 1}, 2) and 3) are
not performed properly, the tape may be
damaged and correct measurements can not
be performed.
5. Do not use worn out or damaged tape, if used
they may damage video heads on the
cylinder. In such a case always replace the
tape with a new one. The replacement tape is
of E- 180, 10 m in length.
w
1-7-3. Tape Transport System
The tape transport system has been precisely
adjusted in the factory, so no check and
alignment are necessary except the followings:
« Noises observed on the screen
* Tape damage
* Parts, shown in the adjustment procedures for
the tape transport system were replaced.
Electrical signal output termina! required for
adjustment differs depending upon the models.
Refer to the test point location in the Electrical
Adjustment Section.
S stant guade
S impedance rover...
S guide roller
{| -—--—__.__
ae,
FE head
MER. SRS)
No. 3 quite -~_—
—
..
Tensioniever& =
= =
_-
Released al REVIEW.
Tension pole
« FIREW mode}
oh
%
ae
ACE adjusling screw tf)
Tit. ——/ fs f
Note:
:
There is S.T wostance roller
f
depending on modals
Fig. 7-3-1 Tape travel diagram
Cylinder ——-----
$ siant guide ———-
--.
<
Tension pole —,,
.
\
T slant guide
\
3
1} Location of tape transport adjustment
<Adjustment reference>
Lower flange height of No. 8 guide is used as
the basic reference for the transport adjustment.
To keep height of the No. & guide, do not apply
excessive force onto the main base to prevent
the main base from deformation. Rectangles
shown in Figs. 7-3-1, 7-3-2 show the adjusting
locations.
2) Tape Transport System Adjustment Flow
Chart (See Next Page).
3) Tape transport system adjustment
<Pre-adjustment>
When the part(s) listed in Table 7-3-1 is
replaced, perform required adjustments by
referring to procedures for the tape transport
system. When the part(s) listed in Table 7-3-1 is
replaced, the tape path may be changed and
may damage alignment tape. To prevent this,
first run a E-240 tape and make sure excessive
tape wrinkle does not occur at each tape guide.
1. If tape wrinkle is observed at the S, T guide
rollers, turn the S, T guide rollers until wrinkle
disappears.
2. if tape wrinkle is observed at the No. 8 guide,
perform the tilt adjustment of the ACE head.
Table 7-3-1
Adjustment
Parts rapiacement
procedure
+ Cylinder assembly
- S, T sliders
+ ACE head
» Pinch iever assembly
* Capstan motor
* No. 9 guide lever assembly
« 8, T guide roifers
« Tension lever assembly
From item 3}
« FE head
From item 4)
* Reel clutch assembly
- S, T reel tables
2
T impedance roller
—-—-|
T guide roller
ACE head
_ ACE
main base
ACE head posaion
adjusting screw
Pinch rover
No.9 guide
-—-
(Pulled ot at
REVIEW mode)
-- Capstan
----—— No. 8 guide
'aaa
___ ACE head posthon adjusting slil
{Insert a slot type screwdriver.)
_
T slant guide
/
Se
.-[ace head]
~--—
Gapstan
No.
3 guide
FEhead—-
--
0-4
Fa
S guide roller] —---—-- -- +
Fig. 7-3-2 Location of tape transport adjust-
ment
~
Pinch roter
'
\ . -————---- No. B guide
oe
come
-- [To guide s rote |
<Adjustment procedures>
1) ACE head assembly coarse adjustment
a. Audio head height adjustment
1. Play back the tape recorded in the SP made.
Observe
the surface of the ACE
head.
2. Turn the ACE height adjusting screw so that
upper tape edge matches to the upper edge
of the audio head core.
b. ACE head tilt adjustment
1. Play back the tape recorded in the SP mode
and observe running condition of the tape at
the lower flange of No.8 guide.
2. Turn the ACE tilt adjusting screw until tape
wrinkle is Caused at the lower flange of No. 8
guide as shown in Fig. 7-3-4 (A).
3.Turn the ACE tilt adjusting screw
counterclockwise until the tape travels along
the lower flange as shown in Fig. 7-3-4 (8).
c. Audio head azimuth adjustment
1. Play back the 7 kHz audio signal on the
alignment tape in the SP mode.
2. Connect a millivoltmeter or oscilloscope to the
audio line output terminal.
3. Turn the ACE azimuth adjusting screw to
obtain maximum audio output.
Audic head core
| :
|
ll : Tape
Control head core
Fig. 7-3-3
{A)
I
No. 8 guide rough adjustment
{8)
Fig. 7-3-4
d. ACE head position adjustment
1. Play back the 3 MHz video envelope signal in
the alignment tape in the SP mode. Loosen
the ACE head position securing screw.
2. insert a siot-type screwdriver into the ACE
head position adjusting slit on the ACE main
base and adjust the ACE main base so that
the video envelope reaches a peak level at
the tracking centerposition when the channel
(tracking) up/down buttons of VTR are
pressed simultaneously.
2) Playback phase adjustment
1. Perform the adjustment according to the
methods stated in the electrical adjustment
(servo circuit).
3) Linearity adjustment
1. Play back the LP mode white video signal on
the alignment tape.
Note:
* For models SP mode only, use the 3 MHz (A
ch) video siganl in the SP mode.
2. Trigger the scope with the switching pulse to
issue the envelope signal output.
3. Make sure the video envelope waveform (in
its maximum output) meets the specification
shown in Fig. 7-3-5. Again make sure the
same by playing back the SP mode 3 MHz
video signal on the alignment tape. If not
satisfied, adjust as foHows:
Note:
a = maximum output of the video RF envelope
b = minimum output of the video RF envelope at
the entrance side
c=
minimum
output of the video RF enveiope at
the center point of cylinder
d = minimum output of the video RF envelop at
the exit side of cylinder
c, b, d/a= 0.75
(S-VHS model}
b, Wa= 0.63
{Non S-VHS model)
cia = 0.75
Fig. 7-3-5
4. If the (A} section in Fig. 7-3-6 does not meet
the specifications, adjust the S guide roller in
up or down direction.
5. lf the (B) section in Fig. 7-3-6 does not meet
the specifications, adjust T guide roller in up
or down direction.
(A)
(B)
aap
Fig. 7-3-6
6. After completion of the adjustment(s), push
the channel (tracking) up/down button and
make sure video envelope variations are
almost flat. Next, play back the 3 MHz SP
mode video signal on the alignment tape and
makes the video RF envelope variations are
also flat when chanhel (tracking) UP/DOWN
buttons is pushed.
7. If the envelope varies like NG figures as
shown in Fig. 7-3-7, perform the adjustment
again. Smooth secondary curves are allow-
able level.
a
OO: a=c ap
Fig. 7-3-7 Abnormal waveform variation
4) ACE head assembly fine adjustment
a. ACE head height fine adjustment
1. Play back the stereophonic alternative
recording 300 - 500 Hz audio signal on the
alignment tape.
2. Adjust the ACE height adjusting screw so that
the signal envelope is obtained almost flat.
cnifiwei
¥
ANNAN
Fig. 7-3-8
Note:
+ If there is no alignment tape (ST-C6, ST-C7),
do not perform this item "a. ACE head height
fine adjustment", and perform the process of
the note in item "e. Audio head height check"
described
later.
b. ACE tilt adjustment
1. Observe the lower flange of No. 8 guide. If
any wrinkle is observed, turn the ACE tilt
adjusting screw counterclockwise until the
wrinkle disappears.
2. If a gap is observed between the lower flange
of No. 8 guide and the lower edge of tape,
turn the ACE tilt adjusting screw clockwise
until the tape travels along the lower flange.
Note:
* This adjustment is performed easily in SP
mode playback, double speed playback mode
or CUE mode.
c. Audio head height check
1. Play back the stereophonic alternative
recorded 300 - 500 Hz audio signal as
described in the step 4)-a, and check if the
audio envelope is flat. if not, repeat the
adjustment described in step 4)-a again.
d. Audio azimuth adjustment
. Play back the 400 Hz, 7 kHz audio signal on
the alignment tape.
2. Turn the ACE azimuth adjusting screw until
the maximum audio output is obtained.
—_
e. Audio head hight check
. Play back the alignment tape desribed in step
4)-a and check if the audio envelope is flat. If
not, repeat the adjustment described in step
4)-a.
—_
Note:
* If there is no alignment tape (ST-C6, ST-C7),
perform the audio height alignment using the
current alignment tape at this adjustment
step.
—_
. Playback the 400 Hz audio signal (SP made)
on the alignment tape.
. Turn each three alignment screw of the ACE
head to the same direction in 45 degrees
steps evenly so that the audio output level
becomes maximum.
3. Perform the confirmation and adjustment for
the tilt and the azimuth again.
NO
f. ACE head postion adjustment
1. Play back the 3 MHz (LP mode) on the
alignment tape.
2. Push the channel (tracking) up/down buttons
simultaneously and reset the tracking at its
center position.
3. Trigger the oscilloscope with the video
switching pulse and observe the video
envelope waveform.
4. Slide the ACE main base until! the maximum
envelope output is obtained as described in
ACE head position coarse adjustment.
5. Play back the 3 MHz video signal (SP mode)
on the alignment tape.
6. Make sure the envelope output is maximum
when the tracking control is placed at its
center position. If no envelope output is
obtained with the tracking control set to the
center position, again adjust it for maximum
envelope output in SP and LP modes. When
envelope output is maximum in the LP mode
at the tracking center, difference with the case
in the SP mode is within 3 ins.
7. Tighten the ACE head position fixing screw
and secure the ACE main base.
Continues after next page...
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