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3. ELECTRICAL MAINTENANCE
A. 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.
B. To replace bulb (National #800-138) .... gently lay microscope on side. Using a Phillips (cross-head) type
screwdriver, remove 5 each 3mm Phillips (cross-head) screws from bottom of base. Remove base plate to
expose bulb. Bulb is held in place by spring pressure clips and is removed by gently pulling bulb straight out
from socket. Replace with new bulb. Replace base plate and 5 Phillips (cross-head) screws.
C. Replacement of fuse (National #801-160)
The fuse is located at rear right side of microscope base. To remove fuse from holder, insert a 6mm
screwdriver blade into slot located in rear of fuse holder cap. Slightly depress and rotate screwdriver ¼ turn
in direction of arrow, release pressure on screwdriver to release the fuse. Pull cap and fuse out of fuse
holder. Insert proper 0.5 amp time delay fuse into fuse cap. Insert fuse cap into fuse holder. Using
screwdriver, rotate fuse cap assembly in opposite direction of arrow until guide slot engages, depress fuse
cap and rotate ¼ turn to lock into fuse holder.
TROUBLESHOOTING
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.
Fuse blown.
Replace fuse (0.5 amp time delay
5mm dia. X 20mm long)
Image does not remain in focus
Stage of microscope drops from
its own weight.
Adjust tension control.
Image will not focus
Rack stop not set at proper
position.
Adjust rack stop.
Slide upside down.
Place slide on stage with cover
slip up.
Slide cover slip too thick.
Use 0.17mm thick cover slip
(No.1 cover slip)
Poor resolution
(image not sharp)
Objective lenses dirty.
Clean objective lenses.
Eyepiece lens dirty.
Clean eyepiece lenses.
Spots in field of view.
Eyepiece or condenser lens dirty.
Clean lens. ***
Specimen slide dirty.
Clean slide.
***Spots in field of view can also result from dirt on inside of eyepiece. It is recommended that you have
service technician clean inside of lens.
OPTIONAL ACCESSORIES AND PARTS:
#610-155R
WF10x eyepiece w/reticle, 10mm/100 div.
#615-045
WF15x eyepiece w/pointer
#800-138
Replacement bulb, 5 watt fluorescent
#801-160
Replacement fuse, 0.5 amp, time delay for 110 volt.
LIMITED LIFETIME WARRANTY
Please see our website,
www.nationaloptical.com
, for complete warranty details and exclusions.
(Revised 2/16/12)
