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.
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 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 can damage the 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:
•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 “FlashlightTest: 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.
