AMSTRAD PC1512 - Index Burst Time Adjustment; Level Check

5-5 Index
Burst
Time
Adjustment
a)
Insert a
CE
diskette.
b)
Move
the
head
to
Track
34
and
check
the
index
burst
times
of top
and
bottom
heads.
Adjust
as
follows
if the
timing
of
one
of the top
or
bottom
heads
is
not as
shown
in
Figure
5-3.
c)
Move the
index
sensor
assembly
back
and
forth by
slightly
loosening
the
index
sensor
assembly
fix
screws to
adjust
the
index
burst
time.
d)
Check
the
index
burst
times
of the
top
and
bottom
heads.
e)
Repeat
from c)
if
adjustment
has
been
unsuccessful.
Measuring
Conditions
Channel
1-TP1
(10mV/div)
MODE-ADD
Channel
2-TP2
(10mV/div)
Sweep-0.1
ms/div
Trigger-
Edge
Connector
J2 8
pin.
Slope
( ••)
I
N
D
Hea
d
Reading
Output Si
( T P I
-
T
? 1 )
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s
270mV.
5-6
Level
Check
a)
Insert a
blank diskette.
b)
Move
the head
to
Track 39
and
write
2F by
the top
and bottom
heads.
c)
Check
that the
average
output
level of
the top
and
bottom
heads
is
more
than
Perform
the
following
if the
output
level is
below
the
required
standard.
d)
Insert
another
blank
diskette
and
reconfirm.
e)
Check
the
spindle
speed as
described
in
5-1.
f) Change
the
oscilloscope
to the
CHOP
mode
and check
the
TP1
and TP2
outputs.
Exchange
the
printed
circuit
board
if one
output
is
small or
missing,
even
if the
probes
are
normal.
g)
Exchange
the head
assembly
if no
problems
are
encountered
in d), e).
and f)
above.
Measuring
Conditions
Channel
1-TP1
(10mV/div)
MODE-ADD
Channel
2-TP2
(10mV/div)
Sweep-20ms/div
Trigger—TP6
Head
Reading
Out
Signal
(TP1-TP2)
^%>wi&P*
^*=*hmji^
A
A
=
270 mV
I"
i
n
13