Rebalancing after alignment of LX90

[netwolf]

Hi All,

I am noting that I can not keep the object in th FOV for long at high magnifications with a 3x and more so with a 5x Barlow. I think it may have to do with imbalance. Given I am switching from no Barlow to 3x or 5x Barlow, I am wondering how i should go about re balancing. If I unlock the Alt axis to do this the Autostar loses its position. Is there some setting in the Autostar I have to activate before unlocking and changing the balance.


Regards

[xstream (John)]

Fahim, it's more likely that you need to train your drives if it's not keeping an object in the field of view. If you unlock your Alt axis you'll have to do an alignment from scratch again as the autostar will have lost where it is on the worm gear.
If you go to page 49 of the LX90 Manual, it explains how to train your drives.

I highly recommend reading the Manual from cover to cover and absorbing it.
Another suggestion is to calibrate everytime you use your scope at startup.

[AndrewJ]

Drive training wont help with tracking errors, only gotos.
If the object is slowly drifting out of the FOV, you more than likely need to adjust yr tracking rate. Its a std setting in the Hbx.
Many LX90 users have to adjust this to get the scope to track at a correct sidereal rate ( esp if PEC is ON )

As to rebalancing on the fly, you can cheat a little if you want.
The scope uses the encoders mounted on the motors to determine where it is.
As such, if you release the clutches, it wont know ( or care ).
Thus, slew to a well identifiable star, Acrux or Rigel Kent are good, as they are unmistakeable doubles, and let it track till stable ( say 10 secs ).
Loosen yr clutches and manually rebalance as reqd. Once done,
manually slew the OTA back to the target star ( without using the HBx )
You can normally get the star back into the centre third FOV of a 26mm EP this way.
Once its close, lock the clutches, fine centre with the HBx and then do a synch. Yr back and running and no loss of alignment.


Andrew

[xstream (John)]

Originally Posted by AndrewJ

As such, if you release the clutches, it wont know ( or care ).
Thus, slew to a well identifiable star, Acrux or Rigel Kent are good, as they are unmistakeable doubles, and let it track till stable ( say 10 secs ).
Loosen yr clutches and manually rebalance as reqd. Once done,
manually slew the OTA back to the target star ( without using the HBx )
You can normally get the star back into the centre third FOV of a 26mm EP this way.
Once its close, lock the clutches, fine centre with the HBx and then do a synch. Yr back and running and no loss of alignment.


Andrew

Thanks Andrew, I just learnt something new also.

Anytime I'd tried a re balance on Anna's scope I couldn't get it to to track correctly (hence a realignment). I now see where my folly was. I should of been manually slewing back to an alignment star instead of using the HBX.

[netwolf]

This is what I tried, I had the scope centred on Saturn and unlocked it for rebalancing I just left the scope where it was and used the hbx to do a goto saturn again and it just sat there. I had assumed there were encoders to feedback to the controller that I had moved the scope around while rebalancing. Surely the servo's have encoders on them used to track there position and realy back to the hbx!

Unless unlocking mean disengaging the motor from the gears! Doh! I think i get it now.

Regards

[AndrewJ]

Gday Fahim

used the hbx to do a goto saturn again and it just sat there

As it will, it still thinks its on Saturn.
The encoders are on the motor, not the OTA
So you go
encoder-motor-gearbox-worm-wormwheel-clutch-OTA
By releasing the clutch, you have no effect on the encoders
The scope just keeps on keeping on, ( happily unaware that you have released the clutches ). Ie it still thinks its tracking Saturn.
Sooooo, when you have rebalanced, YOU must manually recentre Saturn in yr EP, "without using the motors".
If you do this, as the scope still thinks its pointing at saturn, the world is happy again.
A quick synch then tidies it up ( but dont synch on Saturn, use a star )

Andrew

[netwolf]

Thanks Andrew, I understand it now. Also been searching through the LX90 yahoo group and found another method of archiving this. One member suggested that the Scope be put into park mode in the home position, and then rebalanced and put back into the home position (leveled and pointing north). This way you dont need to realign as the scope is ready to go and should still place object in the FOV. I will evaluate both methods. But before I do that I will do as John suggested read the manual cover to cover. Its cloudy now anyway.

I also did the Autostar upgrade to the latest patched firmware so I am guessing it has lost all its drive training etc. So I will need to do this again after reading through the manual.


Out of curiosity is there a software that gives you a virtual hbx control from you laptop? I find that using the hbx to centre object causes vibrations due to the coiled cord. Its even more sensitive when your at high magnifications.
I know you can cotnroll the scope using CDC and Starry night etc, but what I am after is a more simpler Autostar Virtual controller on my screen so I dont need to touch the hbx.


Regards

[AndrewJ]

Gday Fahim

Parking will work, but you still need to reboot to unpark
so its a pain. Just releasing the clutches and manually recentring will give you what you want.
As to drive training, as you have a 497 HBx we cant get yr old data back.
Sooo, unless you wrote down yr old nos, you will need to retrain.
If you have patched firmware loaded, it is possible via the Hbx or my PEC editing app, to manually reset yr training values back to what they were, thus avoiding a retrain, but you needed to log yr old nos.

Autostarsuite has a "full" virtual Hbx. Most apps that use ASCOM
CDC etc shld allow you to bring up a virtual hbx with minimal slew keys.
My PEC editing app also has a panel which has slew keys and nudge keys
as well as focusser control, training and backlash control, but as my app is more for diagnostic/firmware tweaking, i forcibly hog the serial port, so if my app is running, others cant.
It will also have a fully functional remote HBx in the next release, but i broke somebits and havent got round to fixing em yet.

Andrew

[netwolf]

Come to think of it i did do some retraining after the update. I am a newb to Autostar so have no idea when it came to recording details and stuff, did not know that was possible or necessary. Anyway I recall an activity where the telescope moved the star of centre and requested I recentre it using the slew keys.

Regards