National 111 Instructions Manual - page 6
6
3. ELECTRICAL MAINTENANCE
WARNING: For your safety, turn switch off and remove plug from power source before
replacing bulb. Make sure that illuminator housing and lamp are cool before servicing.
A. Remove illuminator field lens housing by rotating in a counter-clockwise direction.
B. Note that the lamp does not screw out. Remove by depressing lamp slightly and rotating in a
counter-clockwise direction until it pops up slightly.
C. This model requires National #800-102 115v 20 watt bulb with D.C. (double contact) medium
bayonet base. This is a bulb specific to microscopes, and should be available from the dealer
from which you purchased the microscope.
D. Insert new bulb, gently depress into socket and rotate clockwise. Carefully wipe new bulb to
insure that it is clean and free of all fingerprints. Any dirt or oil on lamp surface will affect light
efficiency and bulb life.
E. Replace illuminator field lens housing assembly.
TROUBLESHOOTING PROCEDURES
PROBLEM
REASON FOR PROBLEM
SOLUTION
Light fails to operate.
Outlet inoperative.
Have qualified service technician
repair outlet.
AC power cord not connected.
Plug into outlet.
Lamp burned out.
Replace lamp.
Disc diaphragm has not “clicked”
into proper position and is
blocking light source beneath
stage
Turn disc diaphragm until it
“clicks” into position.
Image does not focus
Cover slip on specimen slide too
thick.
Use 0.17mm thick cover slip.
(No. 1 cover slip)
Rack stop not set at proper
position.
Adjust rack stop.
Slide upside down.
Place slide on stage with cover
slip facing up.
Image does not remain in focus
Stage of microscope drops from
its own weight.
Adjust tension control.
Poor resolution
(image not sharp)
Objective lenses dirty.
Clean objective lenses.
Eyepiece lens dirty.
Clean eyepiece lenses.
Too much light.
Adjust disc diaphragm
Spots in field of view.
Eyepiece lens dirty.
Clean eyepiece lenses.
Specimen slide dirty.
Clean slide.