.
' ,.
I.
Complete the previous section on thermocouple zero.
2.
Rotate the TC t/2 set pot full CCW.
3.
Place the filament switch in the preset position if auto filament control is to be
used.
4.
Set the system pressure for the desired trip point�
5.
Slowly rotate the TC 112 set pot CW until the filament light turns on and/or the t/2
process relay energizes.
4.4 Electrometer Zero (check)
I .
Make certain the installation described in section 3 has been completed.
2.
Turn the power switch on. The power on indicator should be on.
3.
4.
5.
6.
Place the auto range switch to the off position and the filament switch to off.
-8
Depress the range switch to the down position until a reading in the 10 range is
achieved.
Observe that the ion gauge meter reads zero
1/2 small division. If not, use a small
screwdriver to slowly adjust 'the electrometer zero located between the range and
autoronge switches until a meter- zero is obtained.
Check the remaining ranges to assure a zero in all ranges.
1f
4.5 Ion Gauge Process Control Set Point Adjustment
The IG process control feature provides relay operation that can be used to control
external devices as a function of system pressure as measured on the ionization gauge. Two
completely independent relay circuits are provided which can be adjusted to operate
anywhere over the pressure range.
I.
IG Set Point Adjust (power off)
It is possible to approximate the set point by visually positioning the screwdriver adjust
slot of the pot to a degree reading as follows:
-8
Slot fully CCW - 0 x 10 (not used)
-8
Slot rotated CW to a horizontal position - 7 x IO Torr or mbar
Slot rotated CW to a 45
°
point above horizontal - 7 x I0-7 Torr or mbar
Slot rotated CW to a vertical position - 5 x I0-6 Torr or mbar
Slot rotated CW to a 45
°
point past vertical - 5 x I
o-
5 Torr or mbar
Slot rotated CW to a horizontal position - 5 x I0-4 Torr or mbar
-3
Slot rotated full CW - 1.2 x 10 Torr or mbar
4-3
