INFICON UL5000 Dry Helium Leak Detector - Manual (Page 49)

Description of the Menu
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6.2.4 Contrast
• Main Menu > View > Contrast
The contrast of the display can be changed. The changes are applied synchronously.
The recommended value under regular conditions is 50 (or close to it).
Tipp If by accident the display has been set too bright or too dark so that it can
not be read off, this may be changed as follows:
6.2.5 Background in Stand-by
• Main Menu > View > Background in Stand-by
The internal background leak rate can be displayed in Stand-by mode (ON) or not
(OFF).The default setting is OFF.
The internal background is generated by residual gas (e. g. helium) that has not been
pumped away yet. Sources for residual gas are air or absorbed gases from the inner
surfaces of the leak detector. This internal background will never disappear totally.
Very clean systems which have been pumped for a long time will show a background
in the 10
-11
mbar l/s range. Under normal conditions the background level is in the
10
-10
mbar l/s or low 10
-9
mbar l/s range.
When pressing START the current internal background is subtracted from all further
measured signals automatically. Thus it is made sure that only the net leak rate from
the part under test is measured.
Switch off the UL5000 and turn it on again. During the run-up phase
press the key no. 3 or 7 so long until the display can be read properly
again. This setting is saved to the EPROM only after confirming this
through the contrast menu. If this setting is not confirmed, the former
setting will be applied after switching on the instrument on again.
Softkey 3: Arrow down
Fade the contrast to dark. The minimum values is 0.
Softkey 4: Invert display
Invert the contrast of the screen.
Softkey 5: ?
Help
Softkey 7: Arrow up
Fade the contrast to light. The maximum value is 99.
Softkey 3: Off
The background leak rate will not be shown.
Softkey 5: ?
Help
Softkey 7: ON
The background leak rate will be shown.