Maintenance - Meade ETX-90AT Astro 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, unthread 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 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
, page 12).
POD
7. The super-gloss anodized 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.
9. A set of two (English-format) hex wrenches is provided with ETX models. These
wrenches are used as follows:
• Small wrench (.05"): Use the small wrench to tighten the set-screws of
any knobs that may loosen (e.g., the focus knob or flip-mirror control
knob).
• Medium wrench (1/16"): This wrench is used to detach the viewfinder
bracket from the telescope's rear cell.
HOW TO ASSEMBLE YOUR TELESCOPE AND TRI-
45