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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 hex socket set screw by rotating in a
counterclockwise direction. With fine focus adjustment at mid-range, focus on a standard slide until
sharp image is obtained. Rotate rack stop 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.
With stage facing you, the tension adjustment collar is located between arm and coarse focus knob
on right side of microscope. With 0.9mm “L” type key wrench, loosen the 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 rubber band will provide a better grip on the tension adjustment collar.
After adjusting, tighten the set screw to lock adjustment 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 LED replacement,
battery recharging and battery replacement. Before maintenance, be sure that recharger is not connected
to microscope.
a. Recharging batteries:
Plug output cord from battery charger into DC recharging socket located on back of microscope
base. Your automatic switching recharger operates on 100 to 240 volts AC 50/60 Hz, plug recharger
into your AC wall outlet. The red LED indicator lamp located on recharger will be illuminated when
batteries are receiving maximum charge. After batteries are charged, the red LED indicator lamp will
turn to green and charger automatically switches to “trickle charge”. The charger can be left plugged
in, but for safety reasons it is a good idea to disconnect the charger from the AC wall outlet and the
output cord from recharging socket after 12 hours. Batteries and charger may feel warm when
charging, and unplugging the recharger is a safety precaution.
You may operate the microscope light even while it is being recharged. Simply flip light switch to “on”
position and continue using microscope while the recharger is fully engaged.
