3M 2100, Service Manual

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MODEL 2100 OVERHEAD PROJECTOR
2-4
CLEANING
The optical components of the overhead pro-
jector require occasional cleaning to remove
the dust and oil which tends to accumulate
and absorb light. 3M Brand Lens Cleaner
(Part No. 78-6969-7086-6) is recommended.
A small amount of mild detergent in water will
serve as a substitute. Use soft, lint-free cloths,
one to apply the solution and another for
drying.
NOTE
Never use paper lens tissues on
projection lenses as they may dam-
age the lens.
Cleaning Stage Glass and Fresnel Lens
When cleaning the underside of the stage
glass and the top side of the Fresnel Lens,
observe the following steps.
1. Pull the Release Latch and lift the top
cover Top Cover Assembly (See Figure).
2. Remove the Top Cover Assembly by pull-
ing either one of two hinges outward until
the hinge pin is out of the hole. Slide the
complete Top Cover Assembly in the oppo-
site direction to release the second hinge
and lift up and out (See Figure).
3. Loosen the four screws holding the Fresnel
Lens in place.
NOTE:
Do not remove the
screws.
4. Turn the retaining clips off to one side.
5. Remove the Fresnel Lens.
6. All surfaces can now be cleaned.
7. Replace all components in reverse order.
Mirrors
The mirror in the Open Lens Projection
Head of all Model 2100 (4100) projectors
are front surface mirrors and must
NOT be
cleaned with a cloth and lens cleaner.
Remove any surface dirt on this mirror with
a Camel Hair Brush only.
Prior to serial number 435242 a front sur-
face type Chassis Mirror was used (clean
as above). After serial number 435242, a
second surface high reflective type is used
and may be cleaned with a soft cloth and
lens cleaner.