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General Maintenance
Both ETX model telescopes are precision optical instruments
designed to yield a lifetime of rewarding applications. Given the
care and respect due any precision instrument, the telescopes
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.
C AU T I O N : Do not touch the aluminized circ u l a r
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 factor y.
5. If either 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 either 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 Assembly
Instructions, page 5).
7. The super-gloss anodized finish of both ETX model's deep-
violet optical tube fades if left in direct sunlight for prolonged
periods.
8. Do not leave either ETX model outdoors on a warm day or
inside a sealed car for an extended period of time;
excessive
ambient
temperatures
telescope's internal lubrication and electronic circuitry.
9. A set of two (English-format) hex wrenches is provided with
both ETX models. These wrenches are used as follows:
Chapter 6: MAINTENANCE AND SERVICING
can
damage
the
z
• 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.
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 (6 and 10, Fig. 1) 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. It is highly recommended to use an
optional carry case to transport the telescope (see OPTIONAL
ACCESSORIES, page 18).
Inspecting the Optics
A Note About the "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 bright spots, or uneven coatings, giving the appearance of
poor quality optics. These effects are only seen when a high
intensity light is transmitted through lenses or reflected off the
mirrors, and can be seen on any high-quality optical system,
including giant research telescopes.
The optical quality of a telescope cannot be judged by the
"flashlight" test; the true test of optical quality can only be
conducted through careful star testing.
Troubleshooting
The following suggestions may be helpful with operation of the
ETX-90EC and ETX-125EC.
The power indicator light on the telescope does
not come on or there is no response when
pressing the Electronic Controller arrow keys:
• Verify that the computer control panel power switch (1, Fig.
5) is in the ON position.
• Verify that the Electronic Controller cord (4, Fig. 6) is firmly
connected to the HBX port (3, Fig. 5).
• If using internal power (batteries), verify that the batteries are
installed correctly and that they have sufficient charge (see
Assembly Instructions, page 5).
NOTE: If the batteries are getting low on charge, there will be
a marked difference in the slew speed. The speed indicator
lights may also flash and the speed may change. If any of these
symptoms occurs, turn the power off and replace the batteries.
• If using an external power source, verify that it is properly
connected between the 12-volt connector (4, Fig. 5) and
either a wall plug (AC source) or a car cigarette lighter (DC
source).
• If the Electronic Controller does not respond to commands,
move the power switch to OFF and then back to ON.
• If the telescope does not slew after power is applied or if the
motor quits or stalls, verify that there are no physical
obstructions that would impede telescope movement.
• If all physical obstacles are removed and the telescope still
does not move properly, turn off the power and unplug the
Electronic Controller. Plug the Electronic Controller back in
and turn the power back on.
19
CHAPTER
6
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