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1. OPTICAL
MAINTENANCE
Do not attempt to disassemble any lens components. Consult a microscope service technician when any repairs not
covered by instructions are needed.
Prior to cleaning any lens surface, brush dust or dirt off lens surfaces using a camel hair brush. Or use air to blow
dust and lint off surfaces. Use of compressed air in a can, available at any computer supply store, is a good source
of clean air.
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 xylene or 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.
Loosen round knurled locking nut by turning counter-clockwise. Then loosen stop screw. With fine focus
adjustment at mid-range, focus on standard slide until sharp image is obtained. Rotate rack stop screw in
clockwise direction until tight. Lock into position with the locking nut. A needle nose pliers might be needed to
loosen the round locking nut.
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 left side of microscope. With a
small jewelers screwdriver, loosen the set screw located in only one of the four holes 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 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.
3. ELECTRICAL MAINTENANCE
The extent of electrical maintenance, by other than a qualified technician, should be bulb replacement. BE CERTAIN
TO TURN SWITCHES OFF AND REMOVE PLUG FROM POWER SOURCE OUTLET BEFORE CHANGING
BULBS.
a. Changing bulb on Models 131 and 132
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