AMSTRAD PC1640 - Adjustments and Checks; Spindle Speed Adjustment; Radial Track Adjustment

5.
Adjustment
and Check
5-1
Spindle Speed
Adjustment (See
Fig.
5-1)
a)
Insert
and clamp a
blank diskette
while DC
motor is
rotating.
b)
Move the head to
trackOO.
c)
Connect the
frequency counter to
TP6
d)
Check that
counter shows
200±3ms.
e)
If the counter
value shows out
of range, turn
the variable
resistor
(VR1
)
on DC
motor
board locates
bottom
of
drive. Spindle speed
goes
slower
by
turning
to
the
left, faster to
the right.
f)
If the
counter value
shows out of range
after
taking method (e),
exchange
the
drive belt
and repeat
from (d).
g)
If the
counter value
still shows out
of range
after exchanging
the
drive belt,
exchange
the
DC
motor
and/or DC
motor board.
VR1
Fig.
5-1
Spindle Speed
Adjustment
5-2
a)
b)
c)
d)
Radial Track
Adjustment (See
Fig.
5-2)
Insert and
clamp
a
CE diskette.
Move the
head
to
track 1 6
and check the
cat's-eye
waveform of the top
and
bottom heads.
Adjust as
follows if one
of the
top
or
bottom head is not
more than 75%
in an
amplitude
ratio of two
waveform.
Slightly loosen
the fixed screws
of the stepping
motor assembly
and move
the stepping
motor back
or forward
to
adjust the
amplitude ratio. The
amplitude of
two wave
forms should be
nearly
the same, then
tighten the
stepping
motor assembly
fixing screw.
Check
the cat's-eye
waveform of top
and bottom heads.
Repeat
from
(d)
if
adjustment fails.
Measuring Condition
Channel 1 -TP1
(10mv/div)
Channel 2 -TP2
(10mv/div),
invert
Mode
-ADD
Sweep
-20ms/div
Stepping
Motor
Assy
-^
X100
75
'A
Fig.
5-2
Radial Track
Adjustment
11