18. Troubleshooting
Review the information in the table below to troubleshoot operating problems.
PROBLEM
I. Optical Section:
LED operates, but field of view remains
dark.
Field of view is obscured or not evenly
illuminated
Dirt or dust is visible in the field of view. Dirt/dust on the specimen
Image looks double
Visibility is poor.
•
Image is not poor.
•
Contrast is poor.
•
Details are indistinct.
•
Phase contrast is poor
One side of the image is unfocused
II. Mechanical Section:
Coarse focus knob is hard to turn
Focus is unstable
CAUSE
Power supply is unplugged.
Brightness is too low
Fluorescence filter selector is not in a
click stop
Fluorescence shutter is closed
Fluorescence filter is not suitable for
the specimen
Revolving nosepiece is not correctly
engaged.
The turret of the phase contrast con-
denser is in an incorrect position
Dirt/dust on the eyepieces
Aperture iris diaphragm is stopped
down too far.
The condenser is not well centered or
it is in a wrong height
Revolving nosepiece is in an incorrect
position
Aperture iris diaphragm is too closed
or too open.
Dust or dirt on lenses (condenser,
objectives, eyepieces and slide)
For transmitted light observation, the
coverglass thickness must not exceed
0.17mm
For phase contrast observation, a
brightfield objective is used instead a
phase contrast one
Phase rings of objective and conden-
ser are not well centered
Objective in use is not compatible with
condenser phase ring
Focus is not even
Revolving nosepiece is in an incorrect
position
Slide is mounted not in a flat position
(tilted)
Poor quality of the glass slide
Tension adjustment ring is too tight
Tension adjustment ring is too loose
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SOLUTION
Connect
Set brightness to a proper level
Move the selector to a click stop
Open the shutter
Use a suitable filter
Make sure that the revolving nosepiece
clicks properly into place.
Move the turret to a click stop
Clean the specimen
Clean the eyepieces
Open aperture iris diaphragm.
Set the condenser according to Koe-
hler settings.
Move the nosepiece to a click stop
Adjust aperture iris diaphragm.
Clean thoroughly.
Use a coverglass with thickness
0.17mm
Usa a phase contrast objective
Operate on centering screws
Use a compatible objective
Slide holder is not flat. Move the speci-
men to a flat position.
Move the nosepiece to a click stop
Place the specimen in a flat position
on the stage
Use a glass slide with higher quality
Loosen tension adjustment ring
Tighten tension adjustment ring