6.13 TEMPERATURE COMPENSATION
(200
TPI ONLy)
The following paragraphs describe
test
configurations,
test
procedures, and adjustment
procedures, respectively,
for
the temperature compensation portion
of
the Temperature
And Write Compensation
PCBA.
6.13.1
TEMPERATURE COMPENSATION TESTS AND ADJUSTMENTS
The temperature compensation portion
of
the Temperature And Write Compensation
PCBA operates in conjunction with a
thermistor
mounted on the positioner baseplate.
Thus, a signal is provided which is proportional to temperature and
offsets
the heads
accordingly
to
compensate
for
ambient temperature changes.
NOTE
Temperature compensation tests and adjustments
must
be performed before any mechanical
CE
alignments are
attempted.
NOTE
All
test points and adjustment potentiometers referred
to
in Paragraph 6.13 are located on the Temperature And
Write Compensation
PCBA
unless otherwise specified.
6.13.1.1
Test Configuration
(1)
Insert the
test
disk
cartridge.
(2)
Operate the
disk
drive in the Ready mode for a minimum
of
20
minutes.
(3)
Connect a disk drive exerciser capable
of
selecting the upper and lower disks and
also capable
of
positioning the heads
to
any desired cylinder address.
(4)
Place a temperature probe within 12.7 mm
(0.5
inch)
of
the thermistor
to
sense the
air temperature.
(5)
Place a second temperature probe on the thermistor mounting block
to
sense the
temperature
of
the metal.
NOTE
Temperature measuring equipment should have a range
from
20°C to 31°C (68°F to 87.8°F) with
an
error
limit
not
greater than ±O.soC
(±
1°F).
(6)
USing a digital voltmeter, connect the positive test lead to
TP4
and the common
test
lead
to
TP5 (ground).
6.13.1.2 Test
Procedure
(1)
Establish the test configuration described in Paragraph 6.13.1.1.
(2)
Observe and note each temperature probe reading and take the average
of
the two
temperatures
if
they are within 10°C (50°F)
of
each other.
(3)
Position the heads
to
cylinder addresses given in Figure
6·21
that are within the
temperature range indicated by the average temperature probe reading as
calculated in Step
(2).
(4)
Observe and note the voltage readings at
TP4
for
each cylinder address in Step
(3).
(5)
If any
of
the voltages noted in Step
(4)
are out
of
tolerance (see Table
6·6),
perform
the adjustment procedure in
Paragraph 6.13.1.3 before continuing with this
procedure.
(6)
Proceed with the Scaling Resistor Vp.rification procedure detailed in Paragraph
6.13.2.
6-47
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