Maintenance; Basic Maintenance; Storage And Transportation; Inspecting The Optics - Meade EXT90 Instruction Manual

MAINTENANCE

Your ETX model telescope is a precision optical
instrument designed to yield a lifetime of rewarding
observations. Given the care and respect due any
precision instrument, the telescope will rarely require
factory servicing or maintenance. Use the following
guidelines:
1. Avoid cleaning the telescope's optics: a little
dust on the front surface of the telescope's correcting
lens causes virtually no degradation of image quality
and should not be considered reason to clean the
lens.
2. When absolutely necessary, remove dust from the
front lens with gentle strokes of a camel-hair brush
or blow it off with an ear syringe (available at any
pharmacy). Do not use a commercial photographic
lens cleaner.
3. You may remove organic materials (e.g.,
fingerprints) from the front lens with a solution of 3 parts
distilled water to 1 part isopropyl alcohol. A single drop
of biodegradable dishwashing soap may be added per
pint of solution. Use soft, white facial tissues and make
short, gentle strokes. Change tissues often.
Caution: Do not use scented, colored or lotioned
tissues or damage could result to the optics.
4. In the very rare situation where cleaning the
inside surface of the corrector lens becomes necessary,
un-thread the lens cell located at the front of the main
tube. The entire correcting lens and secondary mirror
system are mounted in this cell. You may use the lens-
cleaner solution described in step 3 to clean the inside
surface of the lens.
Caution: Do not touch the aluminized circular surface
of the secondary mirror with a finger, a tissue or any
other object. This will almost certainly scratch the
mirror surface.
Note: When cleaning the inside surface of the
correcting lens, leave the lens mounted in its metal cell
throughout the process. Do not remove the lens from
its metal housing or optical alignment of the lens will
be lost, necessitating a return of the telescope to the
Meade factory.
5. If your ETX model is used outdoors on a
humid night, telescope surfaces may accumulate
water condensation. While such condensation does
2
not normally cause any damage to the telescope, it
is recommended that the entire telescope be wiped
down with a dry cloth before being packed away. Do
not, however, wipe any of the optical surfaces. Rather,
simply allow the telescope to sit for some time in warm
indoor air, so that the wet optical surfaces can dry
unattended. In addition, the dust cap should not be
placed back on to the optical tube until the telescope is
thoroughly dry.
6. If your ETX model is not to be used for an
extended period, perhaps for one month or more, it
is advisable to remove the eight AA-size batteries
from inside the drive base. Batteries left installed for
prolonged periods may leak, causing damage to the
telescope's electronic circuitry (see Assembling the
tripod, page 5).
7. The super-gloss painted finish of any ETX
model's deep-violet optical tube fades if left in direct
sunlight for prolonged periods.
8. Do not leave your ETX model outdoors on a
warm day or inside a sealed car for an extended period
of time; excessive ambient temperatures can damage
the telescope's internal lubrication and electronic
circuitry.
Storage and Transport
When the telescope is not in use, store it in a cool, dry
place. Do not expose the instrument to excessive heat
or moisture. It is best to store the telescope in its original
box with the vertical and horizontal locks (Pg. 13 , Fig.
3, 6 and 9) in the unlocked positions. If shipping the
telescope, use the original box and packing material to
protect the telescope during shipment.
When transporting the telescope, take care not to bump
or drop the instrument; this type of abuse can damage
the optical tube and/or the objective lens and knock
the optics out of alignment. It is highly recommended
to use an optional carry case to transport the telescope
(see OPTIONAL ACCESSORIES, page 17).

Inspecting the Optics

A few words about the so-called "Flashlight Test:" If a
flashlight or other high-intensity light source is pointed
down the main telescope tube, the view (depending
upon the observer's line of sight and the angle of the
light) may reveal what appear to be scratches, dark or