4-12
DNW-A220
DNW-A220P
7.
Check to see the followings:
.
The probe is in the middle of the adjacent heads.
.
The positioning flange adheres closely to the outer
circumference of the drum’s upper surface.
.
The legs adhere closely to the outer circumference
of the drum’s upper surface.
.
The value that the dial gauge pointer reads is the
same as before setting (in step 3).
8.
Turn the adjustment screw clockwise until the dial
gauge pointer rotates approximately a half turn.
9.
Turn the outer frame of the dial gauge to align zero (0)
to the pointer.
Measurement of Head Tip Protrusion
n
When rotating the upper drum manually, hold the cover of
the measurement gauge by your hand to not come to turn
the gauge with the drum rotation.
1.
Rotate the upper drum manually counterclockwise (
3
)
very slowly to approach a video head aside of the
probe. (Refer to <A> in Figure 4.)
2.
Read the dial gauge pointer. (= Ha)
n
The scale of the dial gauge is 2
u
m (0.002 mm) pitch.
Clockwise:
+
. Counterclockwise:
_
.
3.
Rotate the upper drum manually counterclockwise (
3
)
very slowly to center the video head in the probe.
(Refer to <B> in Figure 4.)
4.
Read the dial gauge pointer. (= Hb)
5.
Calculate the real head tip protrusion Hr with the Ha
and Hb.
Hr = Hb
_
Ha
6.
Calculate the head tip protrusion Hr for all heads with
steps 1 through 5 performing .
7.
Measure and calculate the real head tip protrusion Hr
for all heads again.
n
Do it two times for fear of measuring error.
Figure 4. Example of Head Tip Protrus Measurement
0
0
(Ex, Ha=2)
(Ex, Hb=40)
40
Dial gauge
Video head A
Probe
Dial gauge
Video head A
Probe
<
A
>
<
B
>
Hr
=
Hb
_
Ha
=
40
_
2
=
38 (
µ
m)
4-4. Video Head Tip Protrusion Check
