Its just won't align (Meade etx 90)

[Lordspace]

So again I've tried to align my Meade etx 90 in polar mode with the wedge. I get everything set as outlined by Meade...

RA is perfectly level.

Dec is at 90° 

I always do this before powering on the scope..

Is this right or wrong??

I then set up, time date and all that.

If I try and use one star align the scope will spin in RA and then it hits the stop and obviously the scope tries to carry on which will strip the gears soon or later.

If I try one star or 2 stars the scope is always way of target.

Am I missing something before I give the mount to the bin men??

 

I am getting super frustrated with this now.

I just want it working for when I get a really clear night.

Cheers.

[westmarch]

Hi there,

I have an ETX 90EC that I use as a grab and go, although not in equatorial mode.  

A couple of points:

Did you first, choose “Polar” from the “Setup: Telescope: Mount” menu in the hand controller?

If you did, then here is a fairly detailed setup guide:

http://www.weasner.com/etx/ref_guides/polar_align.html

It goes into a lot of detail about finding the correct North Celestial Pole alignment (which is near to but not identical with the Pole Star position).

Good Luck!

John

[Lordspace]

It is set to polar mode, also I have out in the right coordinates for my location, I have used that method and many others but none of them actually work.

No matter what I do with one star alignment the scope will always hit the hard stop when sleeping in RA to locate Polaris...

The mount is meant to know apparently where it is so it doesn't hit the hard stop.

If I use one star or 2 star then the scope always missing the target by about a foot. Which is a hell of a lot.

Al the instructions or manuals I've seen just go on and on and get lost in explaining things rather than just getting to the point.

I may just have to take the scope off, seller the tripod and bin the mount as it's actually crap tbh

[westmarch]

Sorry you are having such a hard time with it.  

In older ETX models there is an additional requirement for the home position.  Do you first release the horizontal lock and rotate the scope anticlockwise until it reaches the hard stop and then rotate clockwise until the fork arm aligns with the control panel on the side of the scope? 

The only other thing I can suggest is Does it align in Alt/Az?  If not, it may be that the batteries need replacing - alignment is very sensitive to voltage drop.

John

 

Edited February 23, 2020 by westmarch

[Lordspace]

I haven't tried tbh, I only got it so I could use it to track in RA , I would have just kept my skywatcher Alt-Az if I knew it would be this much hassle getting it just to align. 

But I wanted to get longer exposure's without having to fork out loads for a goto gem. 

[michael8554]

As John/westmarch said, the mount has clockwise and anticlockwise stops, so you have to set  it between those, or it will hit a stop in normal operation.

Sounds like once you have this sorted, you're on the way.

But if the power supply isn't up to the job, you haven't Trained Drives or Backlash, then it's going to miss targets.

You can use it to track in RA without doing any Star Alignment, just MODE out when it gets to that step and the RA should start "ticking", indicating it's tracking.

3 hours ago, Lordspace said:

I may just have to take the scope off, seller the tripod and bin the mount as it's actually crap tbh

Not the world's best mount for a beginner, witness all the questions on the Weasner forum, but it's not crap.

Where are you located? I will give you a hand if not too far, someone closer might do the same.

Michael

[Lordspace]

I'm only new to goto mounts, I've been using gem mounts with polar scopes for a few years.

Admittedly they only had basic RA drives.

I'm in Stoke on Trent.

But not like I get much time to use it due to being under a blanket of cloud for 90% of the year.

Someone said that grease could of got on the optical sensor and that could be confusing the mount.

[PEMS]

I would say the start of  RA is perfectly level and Dec is at 90° is wrong.

I would say the RA should be your Latitude something like 54 degrees, but that is somewhat of a guess. Dec I am unsure of as you in effect aim the scope at Polaris. Although that even if perfect makes you about a degree out

I think you are setting up maybe as equitorially with regards the wedge then setting the scope kind of Level and North as the Alt/Az initial reqiuirements. The Alt/Az is not applicable.

Concerning the end stops the scopes has a limited movement and I think it is a slightly strange rotation of around one and a half times round. So you cannot start in what would be described of as "In the centre". Read the manual for certainty but I think that you have to release the clutch, manually move the scope anti-clock until it hits the end stop, then rotate clockwise until it is pointing forward.

It seems a slightly odd start position, more one way then the other, caused it would seem by the inability to have a full 2 turns. I believe the smaller ETX70's just rotate round and round meaning no end stops and a different internal mechanism and/or connections.

I think that you are mixing the Equitorial set up and start positions with some of the Alt/Az requirements. Friend say that there is little real clear instructions on the equitorial setup. It amounts they say to knowing the angle that has to be set and pointing the axis at polaris with little or no accurate method of doing so as you are aiming the axis of the mount at polaris which may or may not be the scope.

Email from friend says set the timezone to -0 UTC, says they do not like 0. Seems there is a difference between -0 and +0. Might help.

Edited February 25, 2020 by PEMS

[NGC 1502]

One possible way to sort this is to contact a local astronomy club, ask if you can bring the scope to their next meeting. Most clubs are helpful.   If you are invited to do that, make sure you take it with fresh or fully charged batteries.

Hope you sort it, Ed.

[michael8554]

1 hour ago, PEMS said:

Concerning the end stops the scopes has a limited movement and I think it is a slightly strange rotation of around one and a half times round. So you cannot start in what would be described of as "In the centre". Read the manual for certainty but I think that you have to release the clutch, manually move the scope anti-clock until it hits the end stop, then rotate clockwise until it is pointing forward.

That's the truth of it. Sometimes the mount will chose to move eg clockwise, when anticlockwise would be quicker, because of the offset "centre" position.

Annoyingly the handbook mentions the two hard stop but I don't believe it explains the "centreing" procedure.

To add to what PEMS said, the start position is with the OTA and forks pointing at the North Celestial Pole, which I believe you already know.

Michael