6300
6.6.2.4 Adjustment Procedure
When the acceptable
limits
are exceeded, the following adjustments are performed.
(1)
Remove power from the
disk
drive and remove isolation plug J210 from the Servo
PCBA.
(2)
Apply power to the disk drive.
NOTE
The
ON/OFF
switch
will
not
be illuminated when J210 is
disconnected from the
Servo PCBA.
(3)
Connect the positive test lead of the
DVM
to
TP4
and the common test lead to
TP1
on the Servo PCBA.
(4)
Adjust potentiometer
R158
on the Servo PCBA to +
5v
as
observed at
TP4.
(S)
Change the connection
of
the
DVM
positive test lead
to
TP12.
(6)
Adjust potentiometer
R167
on the Servo PCBA to -
Sv
as observed at
TP12.
(7)
Remove power from the disk drive and replace isolation plug J210.
(8)
Apply power
to
the
disk
drive and recheck the +
10v
and -
10v
measurements (see
Paragraph 6.6.2.2).
(9)
Perform recheck
of
+
Sv
and -
5v
power supplies under load, Le., jumper plug
J210 reinstalled.
·0
Acceptable
limits
at
TP18
on the Logic PCBA
• +
S.05v
maximum
• +
4.95v
minimum
o Acceptable
limits
at TP19 on the Logic PCBA
•
- 5.05v maximum
• -
~.95v
minimum
(10)
If the
limits
established in Step
(9)
are exceeded, readjust
R1S8
and
R167
to obtain
+
Sv
and -
Sv
at
TP18 and
TP19,
respectively.
6.6.2.S
Related Adjustments
When adjustments are made to the
+
Sv
and -
Sv
supplies, tests and/or adjustments are
required in
all procedures described in Paragraphs 6.6.3 through 6.6.3.3.
6.6.3
AC
MOTOR
SPEED
CONTROL
The speed control adjustment for the
ac
drive
motor
is made to establish the correct
spindle speed
(1500
rpm or
2400
rpm) within a ± 1 percent tolerance.
6.6.3.1
Test Configuration
(1)
Remove power from the disk drive.
(2)
Disconnect connector
J20S
from the Servo PCBA.
(3)
Disconnect connectors J405 and J406 from the Motor Control PCBA.
(4)
Connect oscilloscope Channel 1 probe to
TP22
on the Servo PCBA.
(5)
Connect the ground clip
of
the oscilloscope probe to
TP1
on the Servo PCBA.
6-12
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