Last updated: 5 July 2006

Mike here: If you are having trouble getting your ETX PE LNT working by following the steps in Meade's documentation, this article may help you.

From: Mike Hogan (


This procedure is mainly applicable to a Meade ETX Premier Edition (PE) ALT/AZ mounted telescope, equipped with a Level North Technology (LNT) Module and Autostar Model #497. Some information may be useful with other models or mountings.

It is presumed the Auto Align feature of the PE series will be the preferred method of alignment. It is also presumed Autostar is using the current version of Firmware. Version 42Ed was current at time of writing; later versions may change some of the prompts and procedures. The Autostar Update (ASU) program and the current Firmware version are available from the Meade Web Site.

When a PE series scope is going to be used for the first time, it is important the Setup steps be performed in the proper sequence in order minimize problems and obtain best performance, especially GOTO's.


Many steps of a first time Setup can be done in your living room without ever removing the lens cover. That way you can become familiar with the procedure without fumbling with Instruction Manuals on a dark night. The Autostar Menu page of the Manual, or a copy, is always handy until you get familiar with Autostar menus and operation.

First, before attempting any Setup or observing session, always make sure the power source is reliable. This means fresh batteries or a known good external source. If you are able to access the Autostar main menu, you can check power status in the Telescope Status Display. This may not be possible if you continually get Motor Unit Faults (MUF). Such condition obviously has to be resolved before continuing.


Note: This Section is only required during setup of a new scope or after a Reset. Subsequent sessions can begin at the AUTO ALIGNMENT Section.

Setting Site Parameters
A new scope must be configured beginning from the Autostar "Reset" state. This will insure no extraneous data remains from possible factory or Dealer testing.

Note: The following steps will automatically Calibrate Motors which should never be performed if the scope is near the full CW or vertical mechanical stop. The first thing the procedure does is drive CW and up; if against either stop, a MUF may occur along with possible drive damage. If necessary, unlock the AZ axis and position about a quarter turn CW from the CCW stop and the ALT axis about horizontal. Make sure both axes are locked then proceed.

With the scope on a flat surface or tripod and the Autostar connected, switch on power. Barring any mechanical or electrical problems, the Autostar should display some initialization messages, ending with a prompt to "Press "0" to Align or Mode for Menu"; hit the Mode key.

Autostar should automatically begin a Calibrate Motors process and display "Testing Motors"; the AZ axis will drive slightly clockwise (CW) and the ALT axis slightly up.

If, instead of performing a Calibrate Motors, the Autostar displays "Align: Automatic", it will have to be Reset before continuing. See the Tips & Troubleshooting section for information on Reset.

Once Calibrate Motors is complete, you will be prompted to create a Site.

Follow the prompts to create a Site and Daylight Saving setting. This step is very important. Autostar will use the latitude/longitude of the Site to calculate the correct Time Zone as well as a coarse correction for the difference between Magnetic North detected by the LNT and True North; Autostar will use these values until a new Site is selected. If the telescope is relocated more than a few miles from the active Site, the values may no longer be valid. A new Site must be created.

Following Site entries, Telescope Model appears. If the default model is not correct, scroll through the list for the right one and Enter to select it. When entries are completed, Autostar will display Align, Automatic.

Use the Mode key to get back to Setup menu and scroll down to Date. Enter the correct Date if necessary, then scroll down to Time. Enter the Local Time as accurately as possible. The LNT internal clock will be initialized with values entered during this step. Do not make any mental adjustments for Time Zone or Daylight Saving as Autostar has already taken these into account based on previous entries.

After all entries are complete, switch off the power.

Setting Telescope Parameters
The next step requires a location with a view of a distant stationary object. Later you will need a view of the star Polaris so if possible select a location that will meet both requirements. The Drive Training process may be done in daylight with a suitable target, or at night with a lighted object such as a street lamp. Smartfinder alignment may be easier during twilight or darkness to get better contrast of the red dot.

Physically position the scope as follows. This configuration should be used for all observing sessions that will use Auto Align.

Unlock the ALT axis, move the Optical Tube Assembly (OTA) approximately horizontal and re-lock; the actual angle is not important. Unlock the AZ axis and rotate fully counter clockwise (CCW) until it stops, then re-lock (Scopes other than PE models may not have stops, e.g. LX90). Moving the ALT axis horizontal first allows easier access to the AZ lock. This is referred to as the "LNT Home" position and is entirely different than that used for non-Auto Alignment.

After the above, the physical position of the entire assembly (base, and tripod if applicable) should be oriented so the OTA is pointing in a Westerly direction. The precise angle is not important; the goal is that the OTA be pointing West of the Magnetic North Pole. The reasons are technical and beyond the scope of this procedure.

Now switch on power. After Autostar initializes you should be at the point where you have the option for Align or Menu. Select Menu.

The next part may be tedious - you need to center the distant object in the eyepiece. You can either unlock both axes to position the OTA manually then re-lock, or use the Autostar "Arrow" and "Number" keys for positioning and controlling the slew rate, or a combination of both. Start with the lowest power eyepiece available then, when centered, select a higher power and re-center it.

If this is the first time you've setup the scope, this is a good opportunity to align the SmartFinder. Just use the object and follow the procedure beginning on Page 13 of the Instruction Manual. Note that the "0" (light) key will turn the dot on and off at any time.

Now, work your way through the Menu to Setup, Telescope, Train Drive and select it. Follow the procedure in Appendix C of the manual, making sure to scroll down to ALT drive after the AZ drive is complete. The more care exercised in this procedure, the better the performance in positioning and tracking.

The final step is to Calibrate Sensors. This requires a view of Polaris (In the Southern Hemisphere the star Sigma Octans is used for calibration).

Note: The calibration values determined during this step compensate for any offset of the position of the electronic components of the sensor array with respect to the optical axis of the OTA. They are usually small and provide a fine correction for True North that is not affected by Site selection or geographical location of the scope. If the calibration star is not visible, the step may be omitted at the expense of slight degradation of GOTO performance.

In the Setup Telescope menu, scroll to Calibrate Sensors and Enter (for some reason, this option is described in the text, but not shown in the Autostar Menu tree diagram in the Manual). You will be prompted to put the scope in the "LNT Home" position.

When positioning is completed, Enter will begin the Align process. This takes a minute or so and the scope may not pause at North or Level. When it finishes the Level, North, Tilt calibration, it will slew to the calibration star with instructions to center it; do so then press Enter.

At this point, cycle the power off/on. Doing so will insure the newly created values will be applied in the following section.


Now that the Location, Date, Time, Drive Motor and Sensor Calibration values have been set you are ready to do a star alignment. Switch on power and after Autostar initializes, hit the "0" key to begin Automatic Alignment.

You will be prompted to set the scope to the "LNT Home" position. When you complete repositioning and locking the axes, hit Enter and the alignment process will continue, eventually stopping at the first alignment star. Follow the prompts until you finish centering the second star and hit Enter. If everything went according to plan, you should see a brief message "Alignment Successful" and the scope will continue tracking the second star.

Keep in mind that after a successful alignment, only the Arrow keys should be used when you need to redirect the scope; unlocking either axis will invalidate the alignment.

From this point you are ready to use all the features of the PE Telescope. GOTO's should position objects so only minor adjustments are necessary.

Assuming Site selection is not changed, and there is no significant change in the power source, the next time you turn on the scope all that should be necessary is an Automatic star alignment. If the physical position will remain undisturbed, you can use the Park function before shutting down. This will retain all alignment values so the next time power is applied no alignment at all will be necessary.


In the Reset condition, the Autostar memory is in its factory default condition; it contains no User Info, no Site parameters, and no telescope calibration values. When a Reset command is executed any such previously stored data is lost. For this reason, Resets should only be used after other methods fail to resolve problems, and you are prepared to do a "first-time" setup.

Telescope Status Display
A list of many current operating parameters can be checked in the Telescope Status Display. Holding the Mode key for 2-3 seconds will open the list; scroll for the desired item. The Finder Set functions are accessed from this list. Hitting Mode again will return to the normal menu.

Battery Status is the first thing to check if the scope starts behaving erratically. Levels below about 75% may cause abnormal performance.

Autostar Update
The ASU program, included in Autostar Suite or as a standalone application available as a free download from Meade, has uses beyond the primary function of updating Autostar firmware. One is modifying the Site list; another is creating "artificial" Landmarks. Such Landmarks can be used to quickly slew to pre-defined coordinates during testing.

Motor Unit Fault (MUF)
There are many things that can cause a MUF. They range from broken gears or wires to corruption of the Autostar memory to the wrong LNT Home position. Mechanical and component failures are beyond the scope of this document.

The wrong LNT Home position will result in Autostar miscalculating the positions of the full CW and CCW stops. It may then drive the scope into a stop resulting in a MUF.

In extreme cases, the Autostar firmware as well as user memory may be corrupted by low or fluctuating power. In such cases, a complete reload of the firmware, followed by a Reset to clear user memory, is required. Less severe cases may only require Calibrate Motors and Train Drives procedures. Optionally, a Reset may be performed first, requiring a complete First-Time setup.

As with all troubleshooting, the first thing to check is the power source.

Poor GOTO Performance
Many GOTO problems are the result of one or more incorrect values for location, time zone, daylight saving, or time.

Try fixing problems by first checking Battery Status, then making sure all values are correct and entered in the proper sequence. Use the Status Display to verify values and Setup menu to change them. These parameters all work together to determine the position of a celestial object relative to a ground based observing site.

Pointing a telescope at the object requires a known starting direction, provided by the Alignment process, and an accurate measurement of scope movement, established during Motor Calibration and Drive Training. Site location is the most critical factor in establishing True North, the initial direction from which all subsequent AZ movement is measured. True Level is determined by the LNT sensor array and is the reference point for ALT movement. If problems persist, try repeating Motor Calibration and Drive Training.

Autostar Prompts for Date during Startup
Each time power is applied Autostar will check for the presence of the LNT internal clock and, if present, retrieve time and date, making the necessary Daylight Saving and Time Zone adjustments for the current Site.

If Autostar doesn't detect the clock it assumes no LNT is available and uses a different section of its Firmware that prompts for user entry of date and time (Autostar is compatible with several scope models).

Possible reasons for not detecting the clock are a failed module, defective wiring or, more commonly, a dislodged battery. A lithium "coin" type battery with about 5-year life powers the LNT clock. Replacement of the battery is covered in Appendix D of the Manual. If reseating or replacing doesn't correct the problem, you may need to contact Meade for LNT replacement.

Site List Full
This error may occur when trying to add or edit a Site using Autostar, even though there are less than 5 in the list (5 is the maximum allowed), and is due to corruption of the list. It can be corrected with a Reset, which also clears drive calibrations. Using the ASU "Edit User Data" tool to retrieve the Owner Info and Site list from Autostar, edit it then send back to Autostar will fix it without clearing the calibration values.

Note: If the current Site lat/lon or Time Zone is edited, Autostar must be reinitialized or power cycled off/on to recalculate the correct location and time parameters.

180 Degree Pointing Error
Occasionally, the scope may slew a 180 degrees away from the expected direction, or drive to a mechanical stop. This can happen with some versions of Autostar Firmware when the base or tripod is setup so the full CCW direction of the OTA is pointing East when Auto Align starts. If the power source is OK and the motors have been calibrated, try reorienting the base and updating to the current version of the Firmware.

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Copyright ©2006 Michael L. Weasner /
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