Crystal 2100 Series - Manual (Page 7)

PRESSURE is Our BUSINESS TM
PN: 2102
8/01
Page 7 of 8
Absolute gauges only: Apply full vacuum to the instrument. When the reference vacuum
gauge indicates 10 milliTorr adjust the front panel ZERO potentiometer for a reading
equivalent to 0.01 mm HgA, ±0.01 mV.
6. If the zero adjustment range of the front panel ZERO potentiometer is inadequate, the
coarse potentiometer must be readjusted. The COARSE ZERO potentiometer is
located beneath the front zero pot, on the opposite side of the PCB. To take the unit
out of the black case, open the battery case then pull the left side of the black case and
gently pull up on the battery case lid, Be sure not to pull too hard, otherwise you may
pull the sensor out of the unit. Adjust the
COARSE ZERO pot until the output is as
close to zero as possible. Trim in the final zero reading with the front panel ZERO
potentiometer.
7.1 On the most sensitive range (usually the bottom most range), pressurize to 50% of the
range.
7.2 Adjust the corresponding front panel span pot so that the indication corresponds
exactly with the pressure standard.
7.3 Pressurize to 95% of range. The reading should be within 0.1% of true pressure. If
not, reset the corresponding front panel span pot until the reading is within 0.1% of true
pressure.
7.4 Reduce pressure to 50% of range. The reading must be within 0.1% of range. If not,
repeat steps 7.1 to 7.4 until both readings are within tolerance.
7.5 Reduce pressure to zero. Reading should be within 0.025% of full scale, or ±1 count,
whichever is greater.
7.6 Repeat steps 7.1 through 7.5 for each successive range.
2121 Only: Milliamp Meter Calibration
8.1 Connect a precision current source to the milliamp input terminals of the 2121.
8.2 Set mA meter to 20mA scale.
8.3 Apply 19.900 mA to meter.
8.4 Adjust the meter with front panel milliamp potentiometer to read exactly 19.900 mA.
8.5 Apply 4.000 mA to meter.
8.6 Reading must be within ±0.004 mA of 4.000 mA.
8.7 Apply 19.900 mA.
8.8 Set mA meter under test to 50mA scale.
8.9 Reading must be within ±0.04mA of 19.900 mA. (There is no adjustment for this
scale).