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MAINTENANCE
WARNING: For your own safety, turn switch off and remove plug from power source before maintaining
your microscope. If the power cord is worn, cut or damaged in any way, have it replaced immediately to
avoid shock or fire hazard.
1. OPTICAL MAINTENANCE
A. Do not attempt to disassemble any lens components. Consult a microscope service technician when
any repairs not covered by instructions are needed.
B. Prior to cleaning any lens surface, brush dust or lint off lens surface using a camel hair brush. You can
also use an ear syringe or canned compressed air, such as that sold by most computer stores.
C. Do not remove eyepieces or objective lenses to clean. Clean only the outer lens surface. Breath on
lens to dampen surface, then wipe with lens paper or tissue or use a cotton swab moistened with
distilled water. Wipe lenses with a circular motion, applying as little pressure as possible. Avoid wiping
dry lens surface as lenses are scratched easily. If excessive dirt or grease gets on lens surfaces, a
small amount of Windex can be used on a cotton swab or lens tissue. To clean objective lenses, do not
remove objectives from microscope. Clean front lens element only, following same procedure.
NOTE: Fingerprints or other matter on the front lens element of the objective lens is the single most
common reason that you will have difficulty in focusing the microscope. Before having costly servicing
done, or before returning to National for "warranty repair", make certain to examine the front lens
element with a magnifying glass or eye loupe for the presence of such contaminants. If a microscope is
returned to National for warranty repair, and it is determined that such contaminants are the problem,
this is not covered under warranty and National will submit a cost estimate for cleaning.
2. MECHANICAL MAINTENANCE
A. The rack stop screw has been pre-adjusted at the factory and should not require re-adjustment.
However, if you do attempt re-adjustment, note the following procedure. Using a 2mm "L" type hex key
wrench, loosen rack stop socket set screw. With fine focus adjustment at mid-range, focus on standard
slide until sharp image is obtained. Rotate rack stop set screw in clockwise direction until tight.
B. Coarse focus tension adjustment prevents the stage from drifting down from its own weight and causing
the image to move out of focus. This has been adjusted at the factory, but over the course of time it may
loosen and cause the stage of the microscope to slip downward on the focusing block.
The tension adjustment collar is located between arm and coarse focus knob on right side of
microscope. Using a 0.9mm "L" type hex key wrench, loosen the socket set screw located in the hole on
tension adjustment collar. Turn collar clockwise to tighten tension, counter-clockwise to loosen tension.
Use of a wide rubberband will provide a better grip on the tension adjustment collar. After adjusting,
tighten the socket set screw to lock collar in place.
NOTE: It is recommended that you leave the tension as loose as possible for ease of focusing, yet not
so loose that it permits the stage of microscope to drift downward from its own weight and cause the
microscope to "drift" out of focus.
C. Metal parts: Use a clean, damp cloth to remove dust or dirt from metal parts, followed by a dry cloth.
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