DISCO DAD 2H/6T, Troubleshooting Manual

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J-7
Cleaning Method of Lens
Use adequate care not to allow dust or fingerprints to contaminate the optical parts such as the lenses.
The surface of the prism inside the ocular lens cylinder and the inside face of the objective lens are particularly
difficult to clean.
(1) Tools required for cleaning
The following items are required for cleaning the optical system.
- xylol or a mixture of ether and alcohol (mixing ratio: about 3:7)
- blower
- hand wrap
- magnifying glass
- lens paper
- soft cotton cloth (after washing off the starch)
- a wooden stick or a small bamboo skewer
- bamboo tweezers
Xylol is not readily available. The mixing ratio of ether and alcohol amy be 4:6 or 3:7. If the ratio of ether
is increased, drying is rapid, while if the ratio of alcohol is increased, oily contamination or the like can
easily be removed but the drying is retarded. The ratio should be determined depending on the applicable
conditions. A blower with a brush is very convenient, or a soft paintbrush can be used. A magnifying glass
with a magnification of 5 to 10 times is adequate. The wooden stick may be a tapered chopstick.
(2) When only dust is attached, scrub with a brush or a paintbrush, or remove with a blower. When dust and oil
are attached, scrub with lens paper or a cotton cloth dampened with a mixture of ether and alcohol.
However, if the lens is rubbed too hard, large pieces of dust or hard particles may cause scratches on its
surface.
(3) Wiping Procedure
Some parts of the optical system are not easily cleaned, even if a lens paper is used dampened with a
mixture of ether and alcohol. Do not attempt to clean these parts in one cleaning; clean them little by little.
This cleaning procedure is the best way. Efficient cleaning requires experience.
(4) When a considerably large lens which is mounted in a metal frame (for example, the ocular lens) is cleaned,
clean it with a folded lens paper dampened with a mixture of ether and alcohol. Hold the folded edge with
an index finger, and clean from the center to the periphery in a circular motion.
The boundary of the lens with the metal frame can be cleaned by utilizing the edge of the folded lens paper.
(5) When a small lens such as the objective lens is cleaned, a lens paper is wrapped around a sharp wooden
stick or a bamboo stick to clean the surface of the lens. Since the surface of the objective lens is multi-
coated, the surface cannot easily be scratched by the tip of the stick. But if a metal screwdriver or metal
tweezers are used instead of a wooded stick or bamboo tweezers, they may scratch the surface of the lens.
So do not use a metal screwdriver or metal tweezers. After cleaning, the surface should be checked with a
magnifying glass; the reflected light of the surface will be observed in the magnifying glass.
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