Veeco MS40 Operation And Maintenance Manual page 89

Fore-line Pirani Calibration
Vacuum Instrument Corp. Vacuum Instrument Corp.
2099 Ninth Avenue 2099 Ninth Avenue
Ronkonkoma, NY 11779 Ronkonkoma, NY 11779
631.737.0900 631.737.0900
1109-186-00 Rev. C
6. On the "A" board mounted on the interior of the rear door, adjust
the R101 potentiometer (at the bottom center of the board) so that
the test port pressure is reading one millitorr on
the alphanumeric display. The optimal method is to adjust the
potentiometer to slightly greater than one millitorr, then slowly
turn the potentiometer down until the display just indicates
1mTorr.
NOTE
Be careful not to over-adjust this setting, while the
potentiometer can be set to a value less than 1 mTorr, the
alphanumeric display will still indicate a reading of 1 mTorr.
1. Ensure that a blank plug is attached to the test port and that all
valves except the fore-line valve are closed. Verify that the MS-40 is
in the Standard mode.
2. Open the rear panel by turning the captive screw at the top of the
panel 1/4 turn counterclockwise and gently lowering the door.
NOTE:
The test port Pirani must be calibrated prior to calibration
of the fore-line Pirani.
3. Using either of the SELECT arrow keys on the left side of the
User Panel, select the TEST PORT (pressure) function. The
function has been selected when the green indicator light to its left is
lit.
4. Set the unit to manually range down to a decade that the unit
will run in while in reverse mode (e.g., the 10
not to range down too far (e.g., if you range down to the 10
then up to the 10
reverse mode). Wait until test port pressure stabilizes. Record the
test port pressure.
5. Using either of the SELECT arrow keys on the left side of the
User Panel, select the FORE-LINE function so that fore-line pressure
reading appears on the alphanumeric display.
6. On the "A" board mounted on the interior of the rear door, adjust the
R79 potentiometer (at the bottom center of the board) until the
Fore-line pressure reading is the same as the test port pressure reading
recorded in Step 4.
-8
range, the unit will be in direct mode instead of
4-20
-8
range). Make sure
-10
range