User Manual

–28–
Arrange the equipment so that the whole surface of the
projection on the load lever assembly is positioned over
the height adjustment tool (VHJ-0111) when seen from
directly overhead.
4-3. TAPE PATH ADJUSTMENT
In normal circumstances, the tape path system does not
need to be adjusted. However, after removing or replac-
ing 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.
4-3-1. ADJUSTMENT PROCEDURE
1. Select a PAL or NTSC alignment tape or blank cas-
sette 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 cap-
stan 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 adjust-
ment,height adjustment and azimuth adjustment on
the audio R/P head (ACE head). When observing the
envelope waveform, bring the CH-1 probe into con-
tact 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 mount-
ing .
2. Position the height adjustment tool (VHJ-0111)
under the full surface of the protrusion on the load
lever assembly
, as shown in Fig.4-3-2.
3. Using your fingers, gently screw the adjustment
nut
clockwise into the nut box (VHJ-0048) until
the protrusion
of the load lever assembly
touches the height adjustment tool (VHJ-0111)
and the screw starts to feel tight. Next, loosen the
adjustment nut
by 270˚ counterclockwise.
4. Load a cassette tape (NTSC: T-160, PAL: E-240). Wind
the tape to the beginning, and repeat FF↔REV five
times (repeat for the same portion 30 to 60 seconds).
If the bottom edge of the tape breaks, rotate the
adjustment nut
in the counterclockwise direction
by about 90˚. Repeat FF↔REV five times again and
check that the tape edge does not break (adjust again
if it does). Next, repeat CUE↔REV five times and
check that the tape is not damaged. If damaged,
rotate the adjustment nut in the clockwise direction
by about 90˚. Repeat FF↔REW and CUE↔REV and
check that the tape is not damaged.
Fig.4-3-1
Fig.4-3-2
0 tape guide
Pinch roller
Capstan shaft
Audio R/P head assembly
(ACE head)
T guide roller
Full erase
head
BT post
T reel
T tape
guide
Cylinder
(Drum)
S tape
guide
S guide roller
S reel
loading guide
Load lever
assembly
Protrusion
Height adjustment
tool (VHJ-0111)
Adjustment nut