JVC HR-XV45SEF Service Manual page 24

4.3.5 Guide Roller Height Adjustment
Purpose of adjustment : To ensure that the bottom surface of the tape can travel along with
4.3.5.1 Prior Adjustment
Fixtures and tools used
Post Height Adjusting
Driver
Adjustment Procedure
1) Travel the tape and check the bottom surface of the
tape travels along with the guide line of the lower drum.
2) If the tape travels toward the lower part of guide line on
the lower drum, turn the guide roller height adjusting
screw to the left
3) If it travels to the upper part, turn it to the right.
4) Adjust the height of the guide roller to ensure that the
tape is guided on the guide line of the lower drum at the
inlet/outlet of the drum. (Fig. C-4-1)
4.3.5.2 Fine Adjustment
Fixtures and tools used
Oscilloscope
Alignment tape
Post height adjusting
driver
1) Play the Alignment tape after connecting the probe of
oscilloscope to the RF envelope output point and the
head switching output point.
2) Tracking control (playback) : Locate it at the center
(Set the RF output to the maximum value via the tracking
control when such adjustment is completed after the
drum assembly is replaced.)
3) Height adjusting screw: Flatten the RF waveform.
(Fig. C-4-2)
4) Move the tracking control (playback) to the right/left.
(Fig. C-4-3)
5) Check the start and the end of the RF output reduction
width are constant.
CAUTIONS
There must exist no crumpling and folding of the tape due
to excess adjustment or insufficient adjustment.
1-24 (No.YD070)
the tape lead line of the lower drum by constantly and adjusting
and maintaining the height of the tape.
VCR (VCP) status
Play or Review Mode
Measuring tools and
connection position
CH-1: PB RF Envelope
CH-2: NTSC : SW 30Hz
PAL : SW 25Hz
Head switching output
point
RF Envelope output
point
Adjustment position
The guide roller height adjusting screw on the
supply guide roller and the take-up guide roller
ADJUSTMENT DIAGRAM
Fig. C-4-1
VCR (VCP) status
Play the standard test
tape.
Waveform
P2 POST ADJUSTMENT
P3 POST ADJUSTMENT
Fig. C-4-2
When the tracking control
locates at the center.
Fig. C-4-2
Connection Diagram
RF ENVELOPE OUTPUT POINT
HEAD RF SWITCHING OUTPUT POINT
GUIDE ROLLER
HEIGHT
ADJUSTMENT SCREW
Adjustment position
Guide roller height
adjusting screw
Flatten the waveform by
lightly turning the guide
roller height adjustment
screw.
When turning the tracking
control to both sides.
OSCILLOSCOPE
CH-1 CH-2