Sony OA-D32W Service Manual page 85

Procedure Ste
eratton
Track positioning
1. Such a Cat's eye pattern signal as shown in Fig. 3-1 (a) can
be obtained at CN-l07-1 on the disk drive when the head
accesses TRK 20, TRK 30, TRK 40 or TRK 50.
The oscilloscope is triggered by the signal at TP-5 of the
MFD checker II.
Hote: Such a signal as shown in Fig. 3-1 (b) can be obtained when
the head accesses TRK 40.
Em
2. SIDE SELECT switch to side 1. such a Cat' s eye pattern
signal as shown Fig. 3-1 (b) can be obtained at CNI07.,.1 on
the disk drive. When the. head accesses TRK 40.
3. Move the head onto TRK 40.
4. Set amplitude L in Fig. 3-1 (b) to 4 divisions, and then
read amplitude R in Fig. 3-1 (b).
Calculate the OFF TRACK value, refering to Table 3-1 (c) and
(d), in accordance with R in Fig. 3-1 (b).
Then, obtain the humidity-compensated OFF TRACK value from
the following expression:
The compensated OFF TRACK value
- OFF TRACK value + O.2(50-H)(32-1.5s)f33.5 .....
(0
Where;
H: Relative humidity (%)
S: Side ID number
Side 0 : 0 Side 1 : 1
The compensated OFF TRACK value should meet the following
formula.
-26
S
Compensated OFF TRACK value
$
+26 ......... (2)
[EX] For R - 3.6 in the OA-D32V, the apparent OFF TUCK value is
as shown in table 3-l.(c).
Assuming the apparent OFF TRACK - 4.5, H - 60%, and S .. 0, we
can obtain the compensated OFF TRACK value as 2.589 from
expression
(1).
This satisfy the formula.
INDEX Pulse
INDEX Pulse INDEX Pulse
I
I
_eJ
(a)
(b)
Fig. 3·1 Cat's Eye Pattern Signal
-3-