Operating Instructions
3
APERTURE REPLACEMENT
Remove the installed aperture by lifting the edge upward. Install a new or
different aperture by inserting the aperture into the light source cavity,
making sure that the aperture is fully seated and pressed flush against the
cavity.
Figure 2. Aperture Removal
NULLING (ZEROING) PROCEDURE
Due to the electronic memory loss caused by power removal, null must be
established each time power to the instrument is removed. Null remains
very stable (
±
0.01D) as long as power remains on.
Null the instrument as follows:
1. Remove film from reading area.
2. Lower the reading head by pressing the read button until it deflects
totally and actuates the switch.
3. Momentarily push the null button.
4. Remove pressure on the read button to release the reading head.
NOTE:
The read button is a read-hold activator. Compress the
button with only as much pressure as necessary for total
deflection.
Read Button
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