Sharp VC-384N Serviceanleitung Seite 13

Precaution:
1. After adjustment, check again when the tape is
running.
2. After adjustment, be sure to adjust tape travel and
the guide rollers (T and S). Then check the height of
the SI roller fixed guide as shown in Figure 21.
e@ Never mode the nut after completion of adjust-
ment.
A/C HEAD REPLACEMENT
Precaution:
After replacement, be sure to adjust tape travel.
During replacement, never touch the head surface by
hand (where indicated with in Figure 23(c)).
© Replacement
1) Unsolder the leads of the A/C head base and remove
them.
2) Loosen two set screws (2) with a hex wrench.
3) Remove screw (3) (3P + 8S) with a screwdriver.
4) Remove A/C head screw (4) with a screwdriver.
Note: The A/C head screw is screwed with a spring
installed together.
5) Remove the A/C head base fitted to the A/C head
assembly.
6) Replace A/C head assembly (5) all together.
I.1. Roller
A/C Head Plate
A/C Head Screw (4)
A/E Head
A/C Head
Height Adjusting Nut
@) Set screw (B)
© A/C Head Ass'y
X-Position
(3) Screw (3P+8S)
Figure 23(b)
1) When mounting the AC head assembly on the chassis,
set the height and tilt adjusting tool as illustrated.
Then adjust the tilt angle by using setscrew B-2.
Plate gap adjustment
A/C head board
a) Screw
Resistors
Set screw
Insert a 2.0 mm gap gauge
into the hatched area.
Install so that the hatched
area becomes level.
Do not touch
the heads!
(A/C head assembly)
Figure 23(c)
13
CHECKING PROCEDURE AND ADJUSTMENT OF A/C
HEAD HEIGHT AND TILT
@ Checking Procedure
1) Load a 180-minute-long tape and select play mode.
2) Check that the tape is not curled at the flange of the
T-fixed guide.
3) Check that the height and tilt of the A/C head are
just as shown in Figure 23(c) in relation to the tape.
Figure 24,
. Adjust the Audio Head tilt angle with the height ad-
justment jig and setscrew B as shown in Fig. 23(a).
2. Turn the setscrews (2)-B and the screw (3) (3P + 8S)
slightly to acheive maximum AUDIO output level.
Note: Over 1.4Vp-p is needed at the maximum posi-
tion of playback level adjusting volume (R602, 652),
and at the same time, adjust for the minimum level
variation.
3. Reproduce 7 kHz Audio signal on the alignment tape
(the video is a stepped wave), and measure the
TP-602 (AUDIO OUT CH-1) and TP-601 (AUDIO
OUT CH-2) of the audio board, on an oscilloscope.
4. Adjust the azimuth adjustment screws (3) (3P + 8S)
so that the outputs of CH-1 and CH-2 becomes maxi-
mum and the phase difference within 30°. (Refer to
figure 25).
5. Recheck the tape travel adjustment.
AIC Head
T.Stationary
' 0~ 0.07 mm
0.05 ~ 0.15 mm
A/E Head
_
I
|
]
{
ae
pe B-
: fee n e a
ee
A:B=A:0 A:B=2:1
(Phase difference 0°) (Phase difference 30° )
Figure 25.
@ Adjustment
@ If the tape does not travel properly, perform the
following Figure 23(a).
1) Load a 180-minute-long tape and check tape travel in
play mode.
2) Check that the tape travels smoothly with its surface
kept level between the guide roller and T-ampedance
roller, between the T-impedance roller and T-fixed
guide, and between the T-fixed guide end capstan
shaft.
3) If the tape skews between the A/C headand T-fixed
guide, it is impossible to obtain proper pictures. So,
check that the tape does not run over the flange of
the T-fixed guide and even fine wrinkles do not
develop.