Veeco MS40 Operation And Maintenance Manual page 72

If the difference between the two readings is greater than 10%, the
measurement gain may be adjusted by pressing the CAL (Calibrate) button
(see below) or the leak detector may be returned and re-calibrated by pressing
the TUNE button (again, see below). If the difference between the two
readings is acceptable (generally less than 10%) the Cal Check cycle can be
ended by pressing the CAL CHECK momentary switch once more.
Another method of checking calibration is a function exclusive to VIC's MS
series of leak detectors: the "Peak Scan" function. Peak Scan allows a user to
quickly ascertain if the leak rate indication is due to helium or is if it is
the result of a poorly tuned spectrometer. To initiate the Peak Scan function:
Vacuum Instrument Corp.
2099 Ninth Avenue
Ronkonkoma, NY 11779
631.737.0900
1109-186-00 Rev. C
3. The indicator on the CAL CHECK switch will now be flashing.
This indicates that the measurement has been completed.
4. The alphanumeric display will now indicate the calculated
temperature compensated value of the internal leak rate
standard. Compare this with the measurement displayed on the
leak rate bar graph and numeric display. If the two readings are
within 10% of each other, the unit is considered to be properly
calibrated.
NOTE
During the warm-up period of the unit (approximately
one-half hour), the leak detector's calibration may not be
as accurate as during normal operation. When using the
MS-40 during warm-up, perform the Cal-Check function
to ensure the integrity of the unit's measurement accuracy.
1. When the unit is leak testing in Standard Mode, press and hold
either SELECT momentary switch until the indicator LED for
the ANODE VOLTAGE function is lit.
2. Press and hold either the left or right "SET" momentary switch.
Pressing the left arrow switch will alter the spectrometer peak
tuning voltage by -30 volts while pressing the right arrow switch
will alter the voltage by +30 volts. Releasing either switch
returns the spectrometer voltage back to normal. When this test
is made on an optimally tuned spectrometer, the displayed leak
rate will decrease to zero
actually due to the presence of helium. Both SET buttons
should be used for this test.
indicating that the measurement is
4-3