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TROUBLESHOOTING
(Continued)
>u!ses
are present,
>
(TP2)
and
10
of
Computer System Board.
If
check
for
pulses
at
pins
Drive Controller
IC
U3.
If
pulses
are miss-
ing,
check
IC
U3.
If
pulses
are
present,
check
the
head
windings
for
continuity,
check
Connector
J9
for
good
connections,
and
check
the
voltages
and
components
associated
with
pins
12
thru
27
of
Read/Write Amp
IC
(U5).
WRITE PROTECT DOES NOT FUNCTION
Type
In
and
run
the
program
listed
under
the
"Will
Not Write" section
of
this Troubleshoot-
ing
guide.
The program
will
display the num-
ber
on the
left
upper corner
of
the
Monitor
screen
if
a
diskette that
is
not write protect-
ed
is
inserted
Into
the Drive
and the number
2
If
the diskette
is
write protected.
WARNING:
This
program
also
writes
on
the
diskette.
Do not use
a
diskette that
has data
on
it
that
is
important.
Insert
a
blank write
protected
diskette
Into
the
Drive
and
close
the door.
While
the
program
is
running,
insert
a
write
protected
diskette
Into
the
Drive
and
check
for
a
logic High
at pin
5
of
Connector
J5.
If
reading
is
not correct,
check Connector
J5
for
good
connections
and
check
the
Write Protect
Sensor
(PQ52).
if
reading
Is
correct,
check
for
a
logic
High at pin
4
and
logic
Low at pin
5
of
Buffer
IC
U4.
If
reading
Is
not correct
at pin
4,
check Drive Controller
IC
(U3).
If
reading
is
correct
at pin
4
and not
correct
at
pin
5,
check
IC
U4.
INDEX
SENSOR
To
check
the
Index
Sensor
circuits,
type
In
and
run
the
program
given
under
"Continuous
Operation
of Disk
Drive" to keep the drive run-
ning.
Insert
a
diskette
In
the
Disk Drive and
close the door.
Check
for
pulses
at
TP1
(pin
3
of
Connector
J5).
If
pulses
are
missing,
check Connector
J5
for good connections,
Resis-
tor RA7 from pin
2
to pin
1
and
the
Index
Sen-
sor
(PQ51).
|f
pulses are present,
check
for
pulses
at
pin
12
of
the Buffer
IC
(U4).
If
pulses are missing,
check the Drive Controller
IC
(U3>.
If
pulses
are
present,
check
for
pulses at pin
11
of
IC
U4.
If
pulses are miss-
ing,
check
IC
U4.
If
pulses
are
present,
check
pin
8
of
Connector
J1
for
good
connec-
tions.
TRACK 00 SENSOR
Disk
Drive
Head
bangs
against
the
Track
00
stop.
Type
in
and
run
the
following
Basic
program
to
check
the
Track
00
detector
circuits.
The program
will
step
the Head
back
to Track
00
and
display
the number
16
on the
Monitor
screen
to
indicate
the
head
is
on
Track
00.
If
the
head
Is
manually pushed off
Track
00
the
number
should
change
to
the
number
0.
DRIVE A
40 FOR T=1
TO
500:
NEXT
T
50 OUT
1014,128:OUT 1010,16:OUT 1010,20
60 S=INP(1012)
70
OUT 1013,4:
S=
I
NPC101
2)
80
OUT 1013,2:S=lhP(1012)
90
CLS:PRINT
INPC1013) AND
16: S=l
NPC101
2
100
GOTO 40
DRIVE
B
10
OUT I014,128:0UT 1010,33:OUT 1010,37
20
OUT 1013,7:S=INP(1012)
30 OUT
1
01
3,
1
:
S=
I
NP
(
1
01
2
40
T=1
TO 500:NEXT
T
50 OUT 1014,128:OUT 1010,33:OUT 1010,37
60 S=INPC1012)
70
OUT 1013,4:S=INP(1012)
80
OUT 1013,2:S=INP(1012)
90
CLS:PRINT
INPC1013) AND
16: S=l NP
C 1
01
2)
100
GOTO 40
If
the number on the Monitor screen
is
not cor-
rect,
check
for
a
logic High
at TP3 when the
head
is
On Track 00 and
a
logic
Low when the
head
is
Off
Track
00.
If
readings
are
not
correct,
check
Connector
J4
for
good
connec-
tions,
check
the
Track
00
Sensor
(M2)
and
Resistor RA7 from pin
5
to pin
1.
If
readings
are correct,
check
for
a
logic High at pin
14
and
a
logic
Low
at
pin
13
of
Buffer
IC
(U4)
with
the head On Track 00 and
a
logic
Low at
pin
14
and
'
a
logic
High
at
ptn
13
with
the
head Off
Track
00.
If
readings are
not
cor-
rect
at
pin
14,
check
Drive
Controller
IC
(U3).
If
readings
are correct
at
pin
14
and
not
correct
at pin
13,
check
IC
U4.
DRIVE MOTOR
Drive Motor
will
not run.
Check Connectors
J1
and
J7
on
the
Disk
Drive Board
for
good connec-
tions.
Check
for
5.0V
at
pin
4
and
12.0V
at
pin
1
of
Connector
J2
on
the
Disk
Drive
Board.
If
the voltages are missing,
check the
power supply.
Type
in
and run the
program given under "Con-
tinuous Operation
of
Disk
Drive"
to
keep
the
Drive
running.
Check
for
a
logic
Low at
pin
16
of
Connector
J1
on
the Disk Drive
Board.
If
reading
Is
not
correct,
check
the
Drive
cable
and
check
the
Disk
Drive
Interface
on
the
Computer
System
Board.
If
reading
is
correct,
check
for
a
logic High
at
pin
3
of
Connector
J7.
If
reading
is
not
correct,
check
the
Drive
Controller
IC
(U3).
If
reading
is
correct,
check
Connector
J7
for
good
connections
and
check
the
Drive
Motor
Control Board.
STEPPING MOTOR
Head position motor
not
working.
Type
In
and
run
the
following Basic
program.
The program
continuously
alternates
the
head
on
Drive
B
between Tracks 00 and
16.
DRIVE
A
10
OUT 1014,128:OUT 1010,16:0UT 1010,20
20 OUT 1013,7:S=INP(1012)
30 OUT 1013,1:S=INP(1012)
10
OUT 1014,128:0UT 1010,16:OUT
20 OUT 1013,7:S=INP(1012)
30 OUT 1013,1 :S=INPC1012)
40
OUT
T=1
TO 500:NEXT
T
1010,20
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