Toshiba W-704C Service Manual page 79

(2) Tape Transport System Adjustment Flowchart
Head assembly (cylinder)
assembly replacement
S, T slider assembly replacement
ACE head assembly replacement
Capstan motor assembly
replacement
Pinch lever assembly replacement
(a) (b)
ACE head assembly
Playback phase adjustment
rough adjustment
Adjust as described in the Electrical
1. AUDIO HEAD HEIGHT
Adjustment Section (Servo circuit.) in
ADJUSTMENT (AUDIO
each service manual.
HEIGHT ADJUSTING SCREW)
Playback the tape recorded in
SP mode. Align position of the
upper end of tape and that of
the audio head.
Audio head
Tape
2. AUDIO HEAD TILT ADJUSTMENT
(TILT ADJUSTING SCREW)
Playback the tape in SP mode
continuously. Adjust Audio head
tilt screw so that tape runs along
lower flange of No.8 guide
Tape
No.8 guide flange
3. AUDIO AZIMUTH ADJUSTMENT
(AZIMUTH ADJUSTING SCREW)
Playback 7 kHz audio signal on
alignment tape and adjust for
max. output.
4. ACE HEAD POSITION
ADJUSTMENT
Playback video envelope
signal 2MHz (A ch) on
alignment tape in SP mode.
Reset tracking control at its
center. Adjust ACE main base
to obtain max. output.
Impedance roller replacement
Tension lever assembly replacement Clutch gear assembly replacement
FE head replacement Reel table replacement
(c) (d)
Linearity adjustment
ACE head fine adjustment
(S, T guide roller)
(Note 1)
1. MAXIMUM ENVELOPE 1. AUDIO HEAD HEIGHT FINE
OUTPUT ADJUSTMENT
Playback the white video
Playback stereophonic
signal on the alignment tape. alternative recording signal
(300-500Hz) on alignment tape.
Trigger scope with switching
Turn the Audio height adjusting
pulse.
screw until audio envelope
Adjust tracking control for maxi-
signal becomes as flat as
mum envelope output by
possible.
pushing tracking up/down
buttons.
2. ENTRANCE SIDE ENVELOPE
ADJUSTMENT
Rotate S guide roller until
entrance side envelope
becomes as flat as possible.
3. EXIT SIDE ENVELOPE 2. AUDIO HEAD TILT FINE
ADJUSTMENT ADJUSTMENT
Rotate T guide roller until exit
Playback alignment tape in CUE
side envelope becomes as flat
or double speed mode.
as possible.
Adjust Audio head tilt until tape
runs along lower flange of No.8
guide.
4. LINEARITY CHECK
Press the tracking up/down
buttons alternately, make sure 3. AUDIO HEAD HEIGHT CHECK
envelope increases or de-
creases with flat response kept.
Playback signal as described in
step 1, make sure audio
envelope signal becomes as flat
as possible.
b a c d
OK
≥ 0.75
c/a
(Non S-VHS model)
4. AUDIO HEAD AZIMUTH
≥ 0.63
b,d/a
FINE ADJUSTMENT
b,c,d/a ≥ 0.75
(S-VHS model)
Playback 7 kHz audio signal on
alignment tape.
Turn the azimuth adjusting
(Note 1)
screw to obtain maximum
output.
For the linearity adjustment (c),
make sure adjusted value should
be checked with 2 MHz/SP mode
after completion of specified
adjustments using 30 % white (SLP)
signal in alignment tape.
5. AUDIO HEAD HEIGHT
RE-CHECK
Repeat same step as step 3.
(e) (f)
No. 9 guide check (at REV mode) Check for transitional operation
1. TAPE WRINKLE CHECK
1. Playback white video signal
(SLP mode) in alignment tape
Playback T-160 tape in
and set review mode.
Review mode.
Confirm the portion of upper/
lower flange on No.8 guide.
2.
Change mode from review to
NG
play and check entrance side
envelope rises within 3s.
(A) (B)
3. Check entrance side envelope
rised within 3s, when mode is
changed from slot-in to play.
2. NO. 9 GUIDE ADJUSTMENT
If tape travels out of upper/lower
NG
flange as shown above, pinch
lever or capstan motor or No.9
guide lever is defective.
Replace the defective part (s).
4. Adjust S guide roller to readjust
linearity.
5. Check step 2 and 3 if no good,
replace S slider assembly or
tension lever.
NG
6. ACE HEAD POSITION
Set tracking at its center
position pressing tracking
up/down buttons
ACE head
simultaneously.
Tilt adjusting screw
Playback white video signal
(SLP mode) on the alignment
tape. Slide ACE main base to
obtain max. envelope.
ACE head adjusting slit
NG Playback 2 MHz video signal
(Insert a slot-type screwdriver.)
(SLP mode) on the alignment
tape.
Confirm that difference from
OK
tracking center is within 3 ms *
VTR applied SP mode only, use
when maximum envelope is 2 MHz (A ch) video signal instead
of white video signal (SLP mode).
obtained.
If not, readjust in SLP mode.
(g) (h)
Recorded & reproduced
Tape damage check
envelope check
Records signals in SP & SLP Run T-160 tape in each mode
modes, using T-120, and check there is no damage
T-160 tape and playback at each guide.
them to check envelopes.
a c
b d
≥ 0.75
c/a
(Non S-VHS model)
≥ 0.63
b,d/a
b,c,d/a ≥ 0.75
(S-VHS model)
OK
Playback mode
Rewinding for synchronous
ACE height
editing mode
adjusting screw
Review mode
ACE head
position securing
Azimuth adjusting screw
(i)
Checks for Hi-Fi models only.
AFM envelope output max.
point check
Playback 3 MHz video signal.
400 Hz AFM signal in alignment
tape ST-NF in SP mode.
Check video envelope max. point
(A-ch).
Check control pulse phase
difference is within ± 3 ms from
that point to AFM envelope max.
point.
Guide roller section damage
Back to step (c) linearity adjustment.
(or Slider assembly replacement)
Damage at No.8 guide brush
Back to step (a) ACE head assembly
rough adjustment.
(or Pinch lever replacement)
Damage at No.3 guide lower flange
Back to step (f) check for
envelope operation.
(or Tension lever replacement)
Damage at No.8 guide flange
Back to step (c) linearity adjustment.
Damage at No.8 guide flange
Back to step (e) No.9 guide lever
check or (a) ACE head assembly
rough adjustment.
(Pinch lever, No.9 lever,
Capstan motor replacement)
Damage at guide roller section
Back to step (c) linearity adjustment.
(or slider assembly replacement)
Fig. 1-7-4