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Meade LX90ACF Problems!!

westmarch

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westmarch

westmarch

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I made the mistake of pairing up with a mate with an LX90ACF for a dark sky session.  I’m set up and happily dobbing away and he is cursing next to me.  Can I help? “Oh Please!”, he replied.

That was the beginning of my descent into the depths of Autostar menus, sub-menus, sub-sub-menus which each trickled across the screen a letter at a time. We could not get this to auto-align, it consistently underestimated altitude and when corrected, primly announced, “auto-alignment failed”.

Three hours later I wanted to tell the goto function to goto......

I checked the date was not American format, checked the latitude and longitude, checked it was not daylight saving, tried with GPS on and off, made sure it was in the home position (level and pointing north - although the instructions talked about turning it anti-clockwise until it hit a stop which I couldn’t find). It was connected to a new 12v car battery so there was no question of voltage drop causing the problem.

Can anyone suggest anything else I could have tried? 

In the end, I saw not one star and had my rationale for getting a Dob vividly reinforced.

John

 

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alacant

alacant

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45 minutes ago, westmarch said:

anything else I could have tried? 

I didn't see any mention of time but the consitently in...

46 minutes ago, westmarch said:

consistently underestimated altitude

... would suggest it was worth a check.

HTH and clear skies.

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Davey-T

Davey-T

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You can tell if it's a time thing by how far out it ends up.

Did you check it was set in Alt / Az mode not EQ ?

Is the GPS working ? it should say getting satellites and then go to the object menu, how old is it ? there's a battery in the GPS but it should last about 10 years.

If you rotate it in RA it should hit a stop in both directions then you centralise and set it to 0 RA.

Easiest thing is to ignore aligning and simply sync on a bright star by holding down the enter key for a few seconds until it says sync on ---- then press enter again to sync.

Dave

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westmarch

westmarch

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3 hours ago, Toxophilus said:

One thought is: was it mounted on an equatorial wedge or not? if so was the correct option in Autostar set for how the scope was mounted? It could have accidentally been changed at some point.

Thank you. It wasn’t on a wedge but I will check the settings. 

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westmarch

westmarch

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3 hours ago, Davey-T said:

Is the GPS working ? it should say getting satellites and then go to the object menu, how old is it ? there's a battery in the GPS but it should last about 10 years.

If you rotate it in RA it should hit a stop in both directions then you centralise and set it to 0 RA.

Easiest thing is to ignore aligning and simply sync on a bright star by holding down the enter key for a few seconds until it says sync on ---- then press enter again to sync.

Dave

Thanks Dave. 

It did check GPS, level, North and tilt and then went to 2 star auto align. 

I couldn’t find a stop.  I rotated it anti-clockwise four times  

I didn’t try one star alignment  I was so focused on problem solving the two star issue.

 

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westmarch

westmarch

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1 hour ago, Peter Drew said:

You say that you "checked the date was NOT American  format, I thought it usually needed to be,  unless it's different for the LX90.    ?

Hi Peter,

i had also heard that was a common problem but the format was,  “11 November 2018”. 

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Davey-T

Davey-T

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I guess Meade have done away with the stops to stop folks banging in to them.

Try stopping  the two star alignment by pushing the mode button then select a bright star in the drop down list, object/ star / named star, GoTo it and centre it using the finder scope then in the eyepiece using the controller, if it's miles out you can loosen the Alt /Az and move it manually, once it's centred then sync on it by holding down the enter key for a few seconds then pressing enter again.

Good luck

Dave

 

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michael8554

michael8554

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Doesn't the gps find location, date, time for you?

But I'm not sure if the Daylight Saving setting is over written by the gps.

Put it on NO just in case.

And without getting into a discussion about levelling mounts, levelling an AltAz mount might help.

Yes, Meade sensibly has month displayed eg November, so no UK/US confusion.

Maybe newer LXs don't have stops but older ones certainly do.

The stops prevent cable wrap which will snap the internal wiring......... !!

4 turns !!   Sounds a bit "Holy Grail"  to me.   ?

I would take off the bottom p!ate and untwist it before the Holy Grenade goes off !

And look for broken off stops.

Michael 

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westmarch

westmarch

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Thanks. Tried it with gps and after cancelling gps.  The base was level to start with. 

I wouldn’t want to open it but not sure that the stops issue would affect altitude. 

I may advise him to do a hard reset and see if that gets us anywhere. 

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Wardr77

Wardr77

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Unless the scope has a fault, aligning the LX90 is a very simple process and normally takes me no more that 2-3 minutes once tripod and OTA are paired up.The basic process for me is as follows in Alt/Az config:

1. Set up the tripod and level it with a surface bubble level; a surface bubble app on a phone or tablet is good for this

2. Mount the scope onto tripod, release clutch and swing the OTA into the horizontal position, use a spirit level on top of the OTA to ensure OTA is properly horizontal. tighten clutch

3. Release clutch in scope base and rotate scope towards magnetic north, tighten clutch.

4. Switch on Audiostar (in my case). The scope will acquire satellites and then start the alignment process by first asking if alignment is to be done by True North or Compass North. For this procedure select compass north

5. You can at this point select your own stars using a 1 or 2 star alignment or let the scope do a 2 star alignment where it selects the stars for you.

6. Once your preferred alignment option is selected the scope will first slew to the first star, you then centre it in FOV (not always in FOV depending on EP used, so finder helps here) press enter and scope will slew to second star centre it and press enter. Message will pop up Alignment Successful and you're good to go.

Piece of cake! Wouldn't be without Goto :) Hope this helps. If this process has been followed and a fault still occurs then something is amiss, which could be cured by simply training the drives or performing a reset. 

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Davey-T

Davey-T

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12 minutes ago, michael8554 said:

Does the gps time differ if you're further away from Greenwich?

Michael

I think you can set it to UTC plus or minus to suit your location.

Using UTC saves worrying about time zones, BST and such.

Dave

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symmetal

symmetal

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1 hour ago, michael8554 said:

Does the gps time differ if you're further away from Greenwich?

Michael

The GPS receiver time output is always UTC so does not change with location. There is no timezone information in the GPS receiver messages. It's up to the software which is using the GPS data to add timezone offsets if it wishes.

Actually, being pedantic, 'GPS Time' is what the GPS receiver gets from the satellites. It's a count in seconds from 6th Jan 1980. It does not take leap seconds into account so is currently 18 seconds ahead of UTC. The GPS messages do contain this offset so the GPS receiver converts 'GPS Time' to 'UTC'. :wink2:

Alan

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westmarch

westmarch

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Thanks to everyone. I’ve gone through all of your very helpful posts. 

It doesn’t seem to be input time related. 

The GPS seems to work- identifying North, position and level. 

The alignment was verified with a 40mm eyepiece. 

Ive just swapped with another Autostar controller and the goto altitude is now correct. It seems to be a software error.  I’ve done a reset and waiting for a clear night to test.

last hope is a firmware update if that fails.

Thanks again.

John

 

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