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Removable parts in a microscope that need replacement include objectives, eyepieces, light bulbs, fuses. In case of repair/ technical support, only competent agency that handles maintenance of instruments should be contacted. Laboratory personnel should never attempt to dismantle any part of the microscope for repair.

Some of the common technical problems encountered, their likely causes and solutions are given in the table below.

Problems Likely causes Solutions
The viewing field is too dim Condenser is too low
Condenser iris diaphragm is closed
Raise condenser to correct its position
Open the diaphragm properly
Dark shadows in the field that move as you turn the eyepiece Surface of eyepiece is scratched
Eyepiece is dirty    
Replace the eyepiece
Clean the eyepiece
Image with the high-power objective is not clear Slide is upside down   
There is an air bubble in the oil
There is dirt on the objective           
Turn the slide over.
Move 100x lens quickly from side to side
Clean the lens
Image with the low-power objective is not clear There is oil on the lens
There is a layer of dust on the upper surface of the objective
Clean the lens
 
Mechanical stage is not moving, too stiff or does not stay up Poor tension adjustment on the mechanical stage
Solidified lubricants
Adjust tension with adjustment knob
Needs service

           

In case, the viewing field is still dim and cloudy, consider the following possible causes and contact the competent personnel for cleaning/ repair:

  • Massive growth of fungus on the lenses or prisms due to storage in a high-humidity environment
  • Penetration of immersion oil between the lenses of the objective
  • A damaged objective (as a result of careless focusing, dropping, rough changing of slides).
Video file

Resources

1.     Module for Laboratory Technicians

2.     Laboratory diagnosis by sputum smear microscopy

 

Assessment

Question Answer 1 Answer 2 Answer 3 Answer 4 Correct answer Correct explanation Page id Part of Pre-test Part of Post-test

What is the possible cause for dark shadows in the field?

 

The scratched eyepiece or dirty eyepiece

 

Broken lens Solidified lubricants Stage stuck 1

Dark shadows in field appear due to a scratched eyepiece or dirty eyepiece.

 

  Yes Yes

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