15 replies to this topic

[GabeRossi]

Hello, after I adjusted the dec setting circle to show 0° when the scope is in the alt/az magnetic north alignment home position I had an issue where the scope stopped successfully aligning. So I reset the hand box(Audiostar A4S4) and entered all the information required and did an align and it successfully found both alignment stars. I did my viewing for the night and shut it down and packed it up for the night. The next night I bring the scope out and go to do an alignment and the alignment fails and says check alignment stars. So my first issue is I go into the menu and the targets defaulted to terrestrial and not astronomical and this will happen every time I power the scope in and off. The second issue is in order for my alignment to work I have ti factory reset the hand box every time I power it up or else the scope will slew way past the point of the first and second alignment stars causing the failure to align. Has anyone been experience this or have a fix?

The lx90 old, it just says Meade lx90 emc on the OTA, there is no gps. It came with the original 497 hand box which had a bad screen so I bought the audiostar hbx and have been using it since. Then only when I adjusted the dec setting circle the alignments started failing. I simply loosened the non knurled or textured knob on the side of the fork arm and turned the circle to have it read the correct numbers on the setting circle plate. Nothing else was changed and it just started happening out of nowhere.

[OzAndrewJ]

Gday Gabe

In AltAz mode, the handset will always default to terrestrial on booting.

On starting an align, it should set to astronomical mode automatically

I cant remember anything being odd with the magnetic North mode

but try it again using True North mode and see if that changes anything.

That said, i havent spent a lot of time looking at A4S4 and its quirks,

i always recommend LX90s use the patched A1F7 firmware.

 

Re needing a reset on every boot, i also have never heard of that

Can you start a boot and align and if it fails, go to the menus,

and see  what mount type is selected????

 

Andrew Johansen Melbourne Australia

[GabeRossi]

Gday Gabe

In AltAz mode, the handset will always default to terrestrial on booting.

On starting an align, it should set to astronomical mode automatically

I cant remember anything being odd with the magnetic North mode

but try it again using True North mode and see if that changes anything.

That said, i havent spent a lot of time looking at A4S4 and its quirks,

i always recommend LX90s use the patched A1F7 firmware.

 

Re needing a reset on every boot, i also have never heard of that

Can you start a boot and align and if it fails, go to the menus,

and see  what mount type is selected????

 

Andrew Johansen Melbourne Australia

Thanks for the reply. When the alignment fails and I go into the menu and select mount it says alt/az. It’s almost like it’s an hour or so behind when it tries to find my two alignment stars but I have my DST on(selected YES) and the date is correct. I can move the scope to the stars but it tells me alignment unsuccessful. My time zone is correct, my zip code that I entered is correct. It’s very odd that once the alignment fails and I select Reset on the hand box and start the process over then it finds the stars. But once I shut down the telescope and turn it back on the alignment fails. I do have another hand box brand new in the box I have been trying to sell so I haven’t wanted to open it. I may have to try it out and see if it solves my issue.

Edited by GabeRossi, 02 April 2024 - 07:10 AM.

[OzAndrewJ]

Gday Gabe

Your symptoms sound very weird to me, esp if you have confirmed timezone.

One other check is it might be a misbehaving encoder.

The LX90s use good quality encoders but thay are mangled in order to fit them.

ie you dont need to calibrate them in order for them to work

but if the motor is flexing etc, it may lose data

Soooo try the spin tests and see what happens

ie Start the mount and then pressnhold mode for several seconds to get to the alternate menus

Now note the "reported" Alt and Az

Slew at high speed for 90deg in each axis

( using the setting circles to measure a "true" distance moved )

Note the reported position

Is it the correct distance, or is it reporting less than expected??

Andrew Johansen Melbourne Australia

[GabeRossi]

Gday Gabe

Your symptoms sound very weird to me, esp if you have confirmed timezone.

One other check is it might be a misbehaving encoder.

The LX90s use good quality encoders but thay are mangled in order to fit them.

ie you dont need to calibrate them in order for them to work

but if the motor is flexing etc, it may lose data

Soooo try the spin tests and see what happens

ie Start the mount and then pressnhold mode for several seconds to get to the alternate menus

Now note the "reported" Alt and Az

Slew at high speed for 90deg in each axis

( using the setting circles to measure a "true" distance moved )

Note the reported position

Is it the correct distance, or is it reporting less than expected??

Andrew Johansen Melbourne Australia

I will check that out later tonight thank you. I kind of dove into that section of the HBX last night just to see what it was reading and with the scope pointing where it was everything matched up. But I will do the full test later. I just think its odd that after a reset everything works as it should then once the scope gets powered off and turned back on I will try to align the scope and it will go past the alignment star too far so when I center it and go to the next one(which also the scope slews way past it) then I click enter it says alignment failed check stars. 

[OzAndrewJ]

Gday Gabe

I will try to align the scope and it will go past the alignment star too far

That is the classic symptom for a failing encoder feedback

In the test i specified, you move the mount a set distance "mechanically"

If the encoder is losing data, it will under report

The reverse effect is if the mount is told to go to a set position ( whilst aligning )

it counts the number of encoder steps, so if it loses some along the way,

it will slew past the target.

As i mentioned, how the encoder is fitted in the LX90s is very dodgy

so if the drive assy flexes during the slew, it might be affecting things.

Andrew Johansen Melbourne Australia

[GabeRossi]

Gday Gabe

That is the classic symptom for a failing encoder feedback

In the test i specified, you move the mount a set distance "mechanically"

If the encoder is losing data, it will under report

The reverse effect is if the mount is told to go to a set position ( whilst aligning )

it counts the number of encoder steps, so if it loses some along the way,

it will slew past the target.

As i mentioned, how the encoder is fitted in the LX90s is very dodgy

so if the drive assy flexes during the slew, it might be affecting things.

Andrew Johansen Melbourne Australia

I will do that test and report back. I’m just thinking if the encoder is failing why would it work when I factory reset? Then I’ll power it off and it won’t align again…just really odd. I keep hoping it’s something stupid that I’m doing but I keep going through the process and I don’t think I am

[OzAndrewJ]

Gday Gabe

I’m just thinking if the encoder is failing why would it work when I factory reset?

No idea at present, but the symptoms suggest doing this test first to

confirm ( one way or another ) if something is going on.

 

Andrew Johansen Melbourne Australia

[GabeRossi]

Gday Gabe

No idea at present, but the symptoms suggest doing this test first to

confirm ( one way or another ) if something is going on.

 

Andrew Johansen Melbourne Australia

Just did the test and all numbers are where they should be. I went 90°for each axis then back to home position and all readings are correct. Nothing seems off and the scope doesn’t look like it missed any steps. I’ll try again tonight to see how it aligns. I will also try my other HBX

Edited by GabeRossi, 02 April 2024 - 05:38 PM.

[GabeRossi]

And now I just setup and 3x now it was able to align. I have changed nothing in my process. I have no idea what happened. I completely powered down the scope each time and then it aligned.

Edited by GabeRossi, 02 April 2024 - 07:38 PM.

[OzAndrewJ]

Gday Gabe

OK, but when you did the spin test, did you check the distance moved after the slew out

as well as when back at home????

ie a "perfectly damaged" encoder will always report being at home properly after a slew out and back

but will under report after 90deg. A "glitching" encoder will not report  home properly either

That said, if it is now aligning OK, it does seem odd????

Maybe temperature based errors???? or something flexing based on position.

No idea, so all you can do is watch.

If it reappears during the night, it will show up as over running the target when doing a goto

or tracking too fast.

Andrew Johansen Melbourne Australia

[GabeRossi]

Yes, I moved the AZ setting circle to 0/0 where the notch was, obviously could not get it perfectly back to 00 00 00” in AZ (I got it to 00 00 15)after rotating about 90 degrees but it was close enough to see everything was working the way it should. I was able to follow the scope as it turned even to 180 degrees and then back home to 0/0. I was looking at both the scope setting circles and the numbers on the hbx. They were very close. Same thing with ALT I went from 0° to 90° and back to 0° on the dec setting circle and I was able to get back to 89 xx xx. Nothing seemed off if I am understanding the process correctly. It’s just really odd that I never had that issue, then I decided to adjust the DEC setting circle to read 0° when i am in the alt/az home position and 90° at the polar home position and I started having this issue... I will keep using it as is and will report back if anything weird happens again. If you want I can take a video of the process you wanted me to complete to make sure I’m doing it correctly. But right now it’s all good and I could not get it to work correctly without resetting the hbx for over a week.

 

I also have never noticed the tracking to be off when on an object after aligning. I could come back a few hours later and its still in the eyepiece. It moved a little bit but it has always tracked well. The only glitch I have seen happen(and does not happen often at all) is when I am using a slow slew speed like 2-3x to center an object the scope will decide to run at max speed for a split second making my object go out of the eyepiece then I recenter the object and its fine. 

Edited by GabeRossi, 02 April 2024 - 08:58 PM.

[OzAndrewJ]

Gday Gabe

OK, it sounds like you are doing the test correctly so no need for a video.

 

The only glitch I have seen happen(and does not happen often at all) is when I am using a slow slew speed like 2-3x to center an object the scope will decide to run at max speed for a split second

That is also a symptom of an encoder feedback failure.

When running, the Hbx sends a single command to the motor to move at a set speed.

The motor then uses the encoder feedback loop to stay at this speed.

If the encoder feedback loop stops working for a time, then the motor card continuosly increases the PWM

to try and catch up and this results in the motor ramping to max speed.

Sooooo, keep a close watch as you may still have an intermittent fault ( which is hard to detect )

Andrew Johansen Melbourne Australia

[GabeRossi]

Gday Gabe

OK, it sounds like you are doing the test correctly so no need for a video.

 

That is also a symptom of an encoder feedback failure.

When running, the Hbx sends a single command to the motor to move at a set speed.

The motor then uses the encoder feedback loop to stay at this speed.

If the encoder feedback loop stops working for a time, then the motor card continuosly increases the PWM

to try and catch up and this results in the motor ramping to max speed.

Sooooo, keep a close watch as you may still have an intermittent fault ( which is hard to detect )

Andrew Johansen Melbourne Australia

How difficult is it to change out the encoder?

[OzAndrewJ]

Gday Gabe

Depends on the exact version you have, but its not simple

as Meade have really butchered the encoder to make it fit in some cases.

There are some old threads showing how the encoder fits

https://www.cloudyni.../#entry11372378
https://www.cloudyni.../#entry12402240

but you need to know what model encoder is fitted to know how hard it is to change.

 

That said, it might not be the encoder, it might be a cable or a buffer chip

in the feedback loop.

Without using a logic analyser to watch the signals,

its almost impossible to tell whats going on with an intermittent fault.

 

Andrew Johansen Melbourne Australia

Edited by OzAndrewJ, 02 April 2024 - 11:52 PM.

[GabeRossi]

Gday Gabe

Depends on the exact version you have, but its not simple

as Meade have really butchered the encoder to make it fit in some cases.

There are some old threads showing how the encoder fits

https://www.cloudyni.../#entry11372378
https://www.cloudyni.../#entry12402240

but you need to know what model encoder is fitted to know how hard it is to change.

 

That said, it might not be the encoder, it might be a cable or a buffer chip

in the feedback loop.

Without using a logic analyser to watch the signals,

its almost impossible to tell whats going on with an intermittent fault.

 

Andrew Johansen Melbourne Australia

Got it thank you