Varian 948, Operation And Service Manual

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Models 947, 948 and 960 Leak Detectors Operations and Service Manual
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5. Press and hold the VENT button approximately 1 second until the 947/948/960 is in
VENT mode.
❑ Test LED goes off.
❑ Vent LED illuminates.
6. Remove the unit under test from the test port.
❑ VENT LED is on.
Auto ranging procedure is complete.
3.5.2 Manual Ranging
Manual ranging is used when the range of the failure level for the part under test is known.
To range manually:
1. Press the VENT button.
❑ TEST LED goes off.
❑ VENT LED illuminates.
2. Select the MAN position of the AUTO/MAN MODE switch in the Leak Rate Range
section.
3. Press the SMALLER or LARGER button to select the exponent of the leak rate range to
which you want to test.
4. Securely attach the new unit under test to the test port while the 947/948/960 is in
VENT mode.
5. Press the START button.
❑ The VENT LED goes off.
❑ The START and TEST LEDs illuminate a second later.
❑ The START LED turns off and the LED Rate Range (exponent) displays at the
selected range.
6. Introduce helium to the item under test. The leak detector automatically traces the
helium signal within the selected range. If larger than the pre-set Reject value, the leak
rate signal reads the maximum level and the Reject LED illuminates.