c) Press and release ‘+ CHARGE’. This will start a manual test where the test voltage
is positive.
(i) The instrument performs an autozero.
(ii) The floating plate is charged to >+1050 volts.
(iii) The plate begins to discharge. If allowed to discharge to <+1000 volts the
timer will start at +1000 volts.
If discharge fails to reach +1000 volts within 200s, ‘Decay failed’ message
will be displayed. Same message will appear if the meter fails to decay to
100 volts within 200 second timer. Test will not be saved and Automatic
decay test will be aborted.
(iv) This is a single positive manual decay test. The test is labeled ‘
M1+
’
(
M
anual, Test
1
,
+
[positive]).
Abort this test by pressing the ‘CANCEL’ button.
d) Use the ‘
CHARGE’ button similarly to perform negative manual decay tests. Up to
ten manual decay tests may be run in any polarity order. The ten tests will be
labeled
1
thru
0
with the polarity indicated. Thus, the 5
th
test might be labeled ‘
M5
’.
3) Shut the instrument off (press and release ‘ON-OFF’). You will need at least an ionizer
and a ground connection to proceed.
Further familiarization —
In order to become more familiar with the accumulation and presentation of data we will
perform two automatic test sequences and a few manual tests and then examine the results:
1. Set up the ionizer.
2. Ground the 287B IPA. The ground jack is located on the left side of the instrument
case.
3. Access the main menu. The display should show 0% values for Automatic and
Manual memory usage.
If a message prompts you to
ClrData
(clear data),
a) Scroll to ‘Y’ with either the
or
button.
b) Accept this by pressing ‘ENTER’.
4. Run an automatic test sequence —
a) Press ‘AUTO’.
b) Let the test run its course. This is ‘
Test 1
’.
i) Six decay tests are run. These are in the order +++
or +
+
+
depending on the current autosequence setup.
ii)
A balance test is run. The duration of the balance test may be any value
between 10 and 90 seconds or it may be turned off in the SETUP menu.
4
