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Meade LX90 Alignment and Tracking Issues

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#1 BPoletti

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Posted 13 January 2021 - 01:55 AM

I finally got out with my new (to me) 8" LX90 ACF GPS.  I think I followed the owner instructions on alignment, but got varying results.  Here's what I did and the results....   

 

I set up the scope so that a bubble level on top of the tube showed level near a rivet above the visual back.  Then the tube was pointed to the north with a compass.  I then tightened the dec and alt releases and rechecked the level and north.  All looked OK.  

 

The scope was powered up, the accessory LNT was not connected.  The GPS took its information and then went to a two star set up.   Even with a 70 degree FoV 38mm eyepiece, the selected stars were not visible in the first two attempts, but I proceeded anyway with the set up with the expected failed alignment (in spite of of the positive report from the audiostar hand controller). 

 

On the third attempt (repeating the exact same process) the scope was FINALLY pointed to Rigel as the second star and I was able to get close enough to GOTO objects to find them in the FoV of the 38mm eyepiece.  Mostly.  

 

But when M42 was selected and slewed into view, the scope would not track it and required continual adjustment to keep it in view,

 

Later in the evening / higher in the sky, tracking seemed to kick in and it took less adjustment to keep it in the FoV.  

 

The images were great under the dark[er] sky conditions we had.  Quite nice and detailed.  

 

HELP!!  What am I doing wrong?  Are there alternative alignment techniques that work better?  Should I connect the LNT?     

 

Thanks for your consideration,

 

Bill

 

 

 

 

 



#2 OzAndrewJ

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Posted 13 January 2021 - 02:06 AM

Gday Bill

What Firmware are you using???

Is the GPS getting the correct date ????

When setting it north, are you using magnetic or true??

The LX90s are pretty accurate when working so its probably down to a setting.

 

Andrew Johansen Melbourne Australia



#3 BPoletti

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Posted 13 January 2021 - 02:17 AM

Gday Andrew.  Thanks for the reply.

 

Not sure of the firmware, but the previous owner was an IT pro and said he kept things up to date as of a couple of months ago.  

 

Using mag north from a compass and selecting compass on the handset.  Not sure if the GPS is setting the date / time / location correctly.  How can I confirm?  

 

I bought the scope form someone 300 miles / 500 km to the east.  Is it necessary to reset the location even though the scope is equipped with a GPS?  

 

Does the LX90 take time to "learn" the scope and location, or is it even that sophisticated?    



#4 colinrasmussen

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Posted 13 January 2021 - 02:41 AM

I finally got out with my new (to me) 8" LX90 ACF GPS.  I think I followed the owner instructions on alignment, but got varying results.  Here's what I did and the results....   

 

I set up the scope so that a bubble level on top of the tube showed level near a rivet above the visual back.  Then the tube was pointed to the north with a compass.  I then tightened the dec and alt releases and rechecked the level and north.  All looked OK.  

 

The scope was powered up, the accessory LNT was not connected.  The GPS took its information and then went to a two star set up.   Even with a 70 degree FoV 38mm eyepiece, the selected stars were not visible in the first two attempts, but I proceeded anyway with the set up with the expected failed alignment (in spite of of the positive report from the audiostar hand controller). 

 

On the third attempt (repeating the exact same process) the scope was FINALLY pointed to Rigel as the second star and I was able to get close enough to GOTO objects to find them in the FoV of the 38mm eyepiece.  Mostly.  

 

But when M42 was selected and slewed into view, the scope would not track it and required continual adjustment to keep it in view,

 

Later in the evening / higher in the sky, tracking seemed to kick in and it took less adjustment to keep it in the FoV.  

 

The images were great under the dark[er] sky conditions we had.  Quite nice and detailed.  

 

HELP!!  What am I doing wrong?  Are there alternative alignment techniques that work better?  Should I connect the LNT?     

 

Thanks for your consideration,

 

Bill

Are you centering each of the alignment stars in the eyepiece before hitting ENTER? I have an LX200 and if you don't the alignment is way off, it you do the accuracy is impressive.



#5 OzAndrewJ

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Posted 13 January 2021 - 03:01 AM

Gday Bill

 

Not sure of the firmware, but the previous owner was an IT pro and said he kept things up to date as of a couple of months ago.

Being an IT pro doesnt mean they knew how Meade handboxes work ;-)

Is the firmware patched?? or original Meade???

Go to the statistics menu to read out the actual firmware loaded

or use my PEC editor app to connect and read out all the data.

http://members.optus...om.au/johansea/

 

Using mag north from a compass and selecting compass on the handset.

I wouldnt trust that to get anywhere near close, unless you have calibrated the sensors and use the LNT.

The hMag deviation tables stored in the mount are years out of date and cant deal with local errors.

You should always try for true North and Level, Much cleaner.

 

  Not sure if the GPS is setting the date / time / location correctly.  How can I confirm?

After fixing, just pressnhold mode for several seconds then release.

This brings up the alternate menus, and if you scroll through them,

one will be local date/time.
 

Is it necessary to reset the location even though the scope is equipped with a GPS?

No. The lat/long will get set correctly via the GPS fix,

but if there is a timezone difference between spots, you will need to reset it manually.

 

Does the LX90 take time to "learn" the scope and location, or is it even that sophisticated?

Nope, one gps fix and it has the lat/long reset. As per above, if there is a timezone change

you may need to do that manually.

 

Andrew Johansen Melbourne Australia


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#6 BPoletti

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Posted 13 January 2021 - 03:15 AM

Are you centering each of the alignment stars in the eyepiece before hitting ENTER? I have an LX200 and if you don't the alignment is way off, it you do the accuracy is impressive.

 

The alignment stars are not visible even in the 38mm 70 FoV eyepiece.  I finally found Rigel on the third attempt and centered it.  Then the scope got close.  Sorta.  The rest is in the original post.  

 

The previous owner was in a different time zone, but since I'm not entering date / time, shouldn't the GPS be picking up on that data?



#7 BPoletti

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Posted 13 January 2021 - 03:19 AM

Gday Bill

 

Being an IT pro doesnt mean they knew how Meade handboxes work ;-)

Is the firmware patched?? or original Meade???

Go to the statistics menu to read out the actual firmware loaded

or use my PEC editor app to connect and read out all the data.

http://members.optus...om.au/johansea/

 

I wouldnt trust that to get anywhere near close, unless you have calibrated the sensors and use the LNT.

The hMag deviation tables stored in the mount are years out of date and cant deal with local errors.

You should always try for true North and Level, Much cleaner.

 

After fixing, just pressnhold mode for several seconds then release.

This brings up the alternate menus, and if you scroll through them,

one will be local date/time.
 

No. The lat/long will get set correctly via the GPS fix,

but if there is a timezone difference between spots, you will need to reset it manually.

 

Nope, one gps fix and it has the lat/long reset. As per above, if there is a timezone change

you may need to do that manually.

 

Andrew Johansen Melbourne Australia

 

I am somewhat technically agile and will check the firmware.  Update is necessary and see if the scope finds the alignment stars.

 

But why didn't it track M42?  

 

And why does it sound like Ripley driving a loader in the "Aliens."  



#8 OzAndrewJ

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Posted 13 January 2021 - 04:11 AM

Gday Bill
 

I am somewhat technically agile and will check the firmware.

Good. That will give us a clue,

as Meade have changed the way their firmware works quite a bit between versions.

 

But why didn't it track M42?

No idea yet. Too little info to go on.

 

And why does it sound like Ripley driving a loader in the "Aliens."

If you mean it sounds like a coffee grinder at high speeds

thats perfectly normal for a Meade  :-(

 

Andrew Johansen Melbourne Australia



#9 BPoletti

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Posted 14 January 2021 - 07:45 PM

Software version is A452.    

 

I was told....

 

"To get a Telrad viewfinder.  (I have no viewfinder at all, now.)  Go through the initial setup, then go to the two-star alignment.  When the first star is selected by Audiostar, slew to the star using the Telrad then the eyepiece.  When the star is centered in the eyepiece, hit enter.  Repeat for the second star.  That process will improve initial alignment."  (more or less a quote)  

 

Also told to that once a good alignment is set, LX90s are very god and stable, minimal chasing.  

 

Are there any other tweaks that might help?  

 

TIA,

 

Bill


Edited by BPoletti, 14 January 2021 - 07:46 PM.


#10 nitegeezer

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Posted 14 January 2021 - 08:09 PM

I will second the suggestion of getting a Telrad. I have one on my LX200 and it works great. One of the issues I have found is that local disturbances of the magnetic field can throw off the scope during initial alignment. When I do outreach events, the accuracy of pointing to the alignment is pretty poor, but by using the Telrad, I can get good alignment for gotos the test of the night. When I get home where I calibrated the sensors, the alignment stars are much better centered to start.

#11 OzAndrewJ

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Posted 14 January 2021 - 08:16 PM

Gday Bill

Software version is A452.

OK, that is actually A4S2, and is out of date as the latest is A4S4.

( A4S2 doesnt know about the GPS rollover )

Sooo, if you have the GPS rollover bug, the GPS fix will get the correct time, lat and long, but the wrong date.

You still havent confirmed if the GPS is getting the correct date yet, so first test is

Boot and let it fix.

Then press'n hold mode for several seconds then release ( to get the alternate menus ).

Scroll to the date/time screen. Are they correct

Go to the LST (Local Sidereal Time ) screen. Is it correct??

( you may need to use a web app to confirm the LST for your location at the time you test )

 

Re Telrad etc, any reasonable red dot finder will do.

You mention having an LNT, and that should have a red dot in it that is just as good when aligned.

 

 

Also told to that once a good alignment is set, LX90s are very god and stable, minimal chasing. 

Are there any other tweaks that might help?

Agreed,

when set up and aligned properly, thet are a very accurate unit.

That said, i dont like A4S4 when used with earlier models of Meades as the firmware has changed

quite a lot and not always for the better.

I always recommend patched A1F7 firmware for the LX90 as it is more stable and has more bug fixes,

incl fixing the GPS rollover.

Only one caveat, if after loading the patch, you find the mount wont resume tracking after a manual position change,

you will need to remove one patch option.

There was a very small run of LX90s that get confused by the  "[Fix AutoRestart Tests]"

I could never replicate it, but it does pop up every now and then

 

Andrew Johansen Melbourne Australia


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#12 BPoletti

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Posted 14 January 2021 - 09:19 PM

Gday Bill

OK, that is actually A4S2, and is out of date as the latest is A4S4.

( A4S2 doesnt know about the GPS rollover )

Sooo, if you have the GPS rollover bug, the GPS fix will get the correct time, lat and long, but the wrong date.

You still havent confirmed if the GPS is getting the correct date yet, so first test is

Boot and let it fix.

Then press'n hold mode for several seconds then release ( to get the alternate menus ).

Scroll to the date/time screen. Are they correct

Go to the LST (Local Sidereal Time ) screen. Is it correct??

( you may need to use a web app to confirm the LST for your location at the time you test )

 

Re Telrad etc, any reasonable red dot finder will do.

You mention having an LNT, and that should have a red dot in it that is just as good when aligned.

 

 

Agreed,

when set up and aligned properly, thet are a very accurate unit.

That said, i dont like A4S4 when used with earlier models of Meades as the firmware has changed

quite a lot and not always for the better.

I always recommend patched A1F7 firmware for the LX90 as it is more stable and has more bug fixes,

incl fixing the GPS rollover.

Only one caveat, if after loading the patch, you find the mount wont resume tracking after a manual position change,

you will need to remove one patch option.

There was a very small run of LX90s that get confused by the  "[Fix AutoRestart Tests]"

I could never replicate it, but it does pop up every now and then

 

Andrew Johansen Melbourne Australia

 

OK....

 

Firmware is A1f7.  Not sure if a patch to that firmware has been applied.   

 

Followed your suggested procedure. 

 

Location city is close enough (12 miles / 20k).  Date is correct (no need for GPS insecticide in the scope).  Time appears to be to the second, but was +1 hour as if the scope is expecting Daylight Savings Time.  I fiddled with initial setup until I found it was set for Daylight Savings Time, was able to delesect DST.  Now time is correct.  Lat and Lon are correct.  Date is correct. 

 

All is well in Happy Valley.  That was while taking a GPS fix in the middle of the house.  

 

In the field, I can understand that the alignment settings might have been off by an hour.  Nothing like being off 15 degrees.  

 

When we get another clear night, the scope will go our to the same location for another test, this time with a Telrad (ordered today) just to make sure and to have that back-up capability.  

 

Will report back with a performance update.  The scope's performance, not mine.  grin.gif    

 

Thanks for the help.


Edited by BPoletti, 14 January 2021 - 09:22 PM.


#13 ZiggyH

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Posted 14 January 2021 - 09:48 PM

Not sure if this will help or pertain to you model, I have LX90 EMC, when I had tracking problems I did the "calibrate motor" procedure and then the "train Drive" procedure and it cured my issues.

 

Ziggy


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#14 OzAndrewJ

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Posted 14 January 2021 - 09:57 PM

Gday Bill

 

Firmware is A1f7.  Not sure if a patch to that firmware has been applied.

Now i am confused :-)

Earlier ypu mentioned it was A4S2 and now is A1F7

Did you load A1F7 ????

The easiest way to tell if it is patched is to connect to my PEC editor app

http://members.optus...om.au/johansea/

On connecting, it will determine if the Hbx is patched.

 

but was +1 hour as if the scope is expecting Daylight Savings Time.  I fiddled with initial setup until I found it was set for Daylight Savings Time, was able to delesect DST.

OK. Main thing to double check here is the raw timezone registered against the site is correct as well.

Most ASCOM drivers for Meades had a habit of applying DST by editing the site timezone vs use the DST setting.

If you do connect via ASCOM at any time, ensure the driver blocks any attempt for the driver itself

to set the mounts time or adjust its site data, if it differs from the mount

 

Andrew Johansen Melbourne Australia


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#15 Mitchell M.

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Posted 14 January 2021 - 09:58 PM

Was out this evening with my lx90.

When you do an alignment, use a higher magnification eyepiece, say a 15mm or a 10mm and defocus a little bit creating a donut; easier to center star in eyepiece. It does make a difference.

Tonight I actually did two alignments. First was with a 25mm, centered as close as possible alignment stars in eyepiece. Eventhough alignment was successful, slewing to a target, the object was just slightly out of the field of view every time. Was able to find object by switching to a lower powered eyepiece. Got tired of doing that real quick.

Then I did a second alignment using the 15mm, centered alignment stars as close as possible and targeted objects were centered every time, even after slewing all over the place and going back to objects viewed earlier.

Like I said, it does make a difference.  


Edited by Mitchell M., 14 January 2021 - 09:59 PM.

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#16 BPoletti

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Posted 14 January 2021 - 10:07 PM

Gday Bill

 

Now i am confused :-)

Earlier ypu mentioned it was A4S2 and now is A1F7

Did you load A1F7 ????

The easiest way to tell if it is patched is to connect to my PEC editor app

http://members.optus...om.au/johansea/

On connecting, it will determine if the Hbx is patched.

 

OK. Main thing to double check here is the raw timezone registered against the site is correct as well.

Most ASCOM drivers for Meades had a habit of applying DST by editing the site timezone vs use the DST setting.

If you do connect via ASCOM at any time, ensure the driver blocks any attempt for the driver itself

to set the mounts time or adjust its site data, if it differs from the mount

 

Andrew Johansen Melbourne Australia

I though I read A452, but when the system initially boots up, it displays A1f7.     

 

The litmus test (failed attempt at red shift humor) will be taking the scope out to our favorite site and testing it.  DST adjustment setting it might be something to remember to check when we go back on DST.    

 

I used to be very detailed and wanted to know all the ugly code in devices.  But since I've retired, I just try to do what is necessary to get the desired results (except for cryptographic vulnerability in a post-Quantum Computing environment).  

 

Sincere thanks for pointing me in the right direction.  



#17 BPoletti

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Posted 14 January 2021 - 10:09 PM

Was out this evening with my lx90.

When you do an alignment, use a higher magnification eyepiece, say a 15mm or a 10mm and defocus a little bit creating a donut; easier to center star in eyepiece. It does make a difference.

Tonight I actually did two alignments. First was with a 25mm, centered as close as possible alignment stars in eyepiece. Eventhough alignment was successful, slewing to a target, the object was just slightly out of the field of view every time. Was able to find object by switching to a lower powered eyepiece. Got tired of doing that real quick.

Then I did a second alignment using the 15mm, centered alignment stars as close as possible and targeted objects were centered every time, even after slewing all over the place and going back to objects viewed earlier.

Like I said, it does make a difference.  

 

The problem I had was that I couldn't get the alignment stars in the field of view at all.  As noted above, the time used by the scope was one hour off.  We'll see how it works now that the time seems more accurate.



#18 OzAndrewJ

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Posted 14 January 2021 - 10:15 PM

Gday Bill

I though I read A452, but when the system initially boots up, it displays A1f7

OK, if thats the case, and the prev owner did keep it up to date, then it probably is patched.

Again, an indoor test by just connecting to my app will show that.

 

Getting the correct LST will certainly help on getting the align stars in view

so good luck. It is well tested firmware so should work.

 

Andrew Johansen Melbourne Australia


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#19 Mitchell M.

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Posted 15 January 2021 - 05:57 PM

You mentioned in your first post not having the LNT module plugged in. Why is that? I think the scope uses input from the LNT for leveling and to detect tilt. Perhaps Andrew can clarify. Not an awful lot of information available on the LNT module.

The LNT also doubles as a red dot scope. During the alignment procedure, when it comes time to center the alignment stars, the laser red dot is turned on and you first slew the scope using the red dot and then transition to the finder scope, slew and then to the eyepiece to complete centering. Usually you can skip using the finder scope if your red dot is spot on. The LNT module also has a button battery. You may need to replace with new. I seem to recall reading, this was years ago, folks having problems with alignment that was solved by simply replacing the battery in the LNT.


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#20 BPoletti

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Posted 15 January 2021 - 09:14 PM

You mentioned in your first post not having the LNT module plugged in. Why is that? I think the scope uses input from the LNT for leveling and to detect tilt. Perhaps Andrew can clarify. Not an awful lot of information available on the LNT module.

The LNT also doubles as a red dot scope. During the alignment procedure, when it comes time to center the alignment stars, the laser red dot is turned on and you first slew the scope using the red dot and then transition to the finder scope, slew and then to the eyepiece to complete centering. Usually you can skip using the finder scope if your red dot is spot on. The LNT module also has a button battery. You may need to replace with new. I seem to recall reading, this was years ago, folks having problems with alignment that was solved by simply replacing the battery in the LNT.

Great question!

 

The scope was purchased used.  The LNT module was attached by a single screw and knocked very much out of alignment.  When I started truing to get an alignment n the back deck during daylight, the scope was pointed about 5 degrees off north and not level.  Results were not repeatable.  So I just unplugged the LNT because of "stability issues."

 

Now that I've addressed at least two problems, I might try it again if testing proves the corrections worked.   



#21 alder1

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Posted 16 January 2021 - 04:47 AM

A really simple alignment fix I learned here on this forum: make sure that the OTA is level through 360 degrees. The little bubble level isn’t accurate. I use a small carpenters level on top of the scope. This really helps!
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#22 Makka

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Posted 17 September 2021 - 07:55 PM

...

Only one caveat, if after loading the patch, you find the mount wont resume tracking after a manual position change,

you will need to remove one patch option.

There was a very small run of LX90s that get confused by the  "[Fix AutoRestart Tests]"

I could never replicate it, but it does pop up every now and then

 

Andrew Johansen Melbourne Australia

I also had the same problem as BPoletti where scope stops tracking after a manual adjustment. I was tearing my hair out until I noticed this post, so thank you!!! OzAndrewJ for pointing out the solution, i.e. unticking [Fix AutoRestart Tests] when performing a StarPatch update.

 

My Meade LX-90 ACF 8", purchased in late 2009, has had problems on occasions with not being able to manually slew up and down (left and right was fine). I fixed this by removing the spur gear in the right fork arm and regreasing it (and the worm gear), but then this tracking problem appeared after upgrading to the latest StarPatch (build A1F7, patch v08).

 

Happy now, but this Meade has been a bit problematic due to these issues, and its tracking accuracy is not great - I would not use it for long-exposure astrophotography, even if I had a polar mount.  Maybe a Celestron would be better for this type of thing.  Not switching now - I've done too many customisations to the Meade to warrant the hassle.



#23 OzAndrewJ

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Posted 17 September 2021 - 08:49 PM

Gday Makka

Good to hear it now works again :-)

As i noted, i still dont know why it happens.

The patch is used on all manner of mounts happily,

Its just one small subset of LX90s that dont play.

 

As to general tracking, Meades worm and wormwheel arent exactly top quality

and recently, the gears in the gearbox have also been reported to have dropped in quality.

Its just the result of designing to a price.

The best test you can do is set up polar and use an app like PHD/Metaguide/PEMPro

to get say 10 revs of the worm unguided and with PEC OFF

and then overlay them by worm period.

The shape and consistency of that model will give you an idea of what your mount is like

( as each mount can look very different )

Andrew Johansen Melbourne Australia




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