WPI EVOM - Tips and Advice

6 World Precision Instruments
CAUTION: Not all USB drives work on the EVOM™ Manual.
To test a USB drive, see "Sample Resistance File (*.csv)" on page 23. This test saves
a le to the drive and reads it back. A system message reports if the USB ash drive
is usable, or it will display an error. If the USB ash drive is not plugged in or it is not
recognized, a warning message will appear. Press
Cancel and try again. The Store
function cannot be used on an unrecognized drive. EVOM™ Manual should respond
with “File saved” within 15 seconds. If “Saving le...” is still seen after 20 seconds, press
the Return key and use another USB ash drive. Once a le has been saved, open the
le on a computer to verify the contents.
Tips and Advice
Out of Range Error
If you see –––– (5 dashes) on the main resistance display, then the resistance reading
is out of range. Check the ohms range setting to see if it can be increased to display a
higher resistance or set it to Auto . If the display still shows ––––, then go to the Blank
Handling screen and check the settings and the reading. A saved reading will show a
space (“ “) in the grid if the display shows out of range. Do not forget to reset the blank
to zero or go back to a control well resistance when you are nished.
NOTE: The 100K Range can read 5% over to 105K Ω.
Zeroing the blank handling value
1. Select Setup .
2. Then, press Short Electrodes .
3. Press the Blank Handling button.
4. Set the reading to zero.
5. Return to the Setup page and open the electrodes to remove the short.
Zeroing the probe null oset
1. Select Setup .
2. Then, press Short Electrodes .
3. Press the Probe Null button.
4. Set the reading to zero.
5. Return to the Setup page and open the electrodes to remove the short.
Resistance levels that are unexpectedly lower or higher can be attributed to a number
of things besides an incompletely grown membrane. Any of these items can change
the resistance reading:
• Electrode resistance (Keep the electrodes clean.)
• Fluid levels (Try to maintain the same volume for every insert. A variation of 50µL
can have a large eect in a small insert.)