Sony SLV-E120AE, Руководство по обслуживанию

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5-27
4-3. TAPE PATH ADJUSTMENT
In normal circumstances, the tape path system does not
need to be adjusted. However, after removing or replacing
one of the parts shown in Fig. 4-3-1, you should check and
adjust the tape path. The adjustment of the tape path is
carried out while monitoring the envelope waveform of the
video head output, using an oscilloscope. To make sure
that the tape drawn off the reel runs freely and without
excessive tension along all the tape guides and cylinders
(drums), it is also important to check each tape guide by
eye.
S reel
T reel
T guide roller
S guide roller
Audio R/P head assembly
(ACE head) Capstan shaft
Loading guide
T tape
guide
Pinch roller
Cylinder
(Drum)
Full erase
head
S tape
guide
BT post
0 tape guide
Fig. 4-3-1
4-3-1. ADJUSTMENT PROCEDURE
1. Select a PAL or NTSC alignment tape or blank cassette
tape, according to the transmission system of the VCR
you are repairing.
NTSC: For models with 525 scanning lines and a field
frequency of 60Hz
PAL: For models with 625 scanning lnes and a field
frequency of 50Hz
2. Clean the tape guides, the cylinder(drum), the capstan
Shaft, the audio R/P head (ACE head) and the full
erase head.
3. Using an oscilloscope, adjust the height of the guide
roller and carry out horizontal position adjustment,
height adjustment and azimuth adjustment on the audio
R/P head (ACE head). When observing the envelope
waveform, bring the CH-1 probe into contact with the
envelope waveform test point, and bring the CH-2 probe
into contact with the switching pulse (SW P) test point.
While adjusting the tape path, set the trigger at the low
side of the switching pulse (SW P) in order to observe
the output waveform on the CH-1 side of the video
head.
NOTE:The contact point for the oscilloscope varies from
one model to another, so to find the correct point for your
model, refer to the figure entitled “Test point for tape path
adjustment” in the electrical circuit section of the service
manual.
4. When checking the tape path by eye, use a dental
mirror.
4-3-2. LOAD LEVER ASSEMBLY HEIGHT
ADJUSTMENT (See Fig. 4-3-2)
1. Refer to sections 3-9-2, and remove the opener
mountIng .
2. Position the height adjustment tool (VHJ-0102)
3
under
the full surface of the protrusion
2
on the load lever
assembly
1
, as shown in Fig. 4-3-2.
3. Using your firlgers, gently screw the adjustment nut
4
clockwise into the nut box (VHJ-0048)
5
until the
protrusion
2
of the load lever assembly
1
touches the
height adjustment tool (VHJ-0102)
3
and the screw
starts to feel tight. Next, loosen the adjustment nut
4
by 270° anticlockwise.
4. Load a cassette tape (NTSC: T-160, PAL: E-240) and
switch to PLAY mode. Check that when you do this, no
scratches appear on the upper or lower edges of the
tape. If scratches do appear, re-adjust the height.
Arrange the equipment so that the whole surface of the
projection on the load lever assembly is positioned over
the height adjustment tool (VHJ-0102) when seen from
directly overhead.
5
Nut box
(VHJ-0048)
3
Height adjustment
tool (VHJ-0102)
1
Load lever
assembly
2
Protrusion
4
Adjustment nut
Fig. 4-3-2