Mesu 200 Mk2 Tracking stops close to equator


T. van Hees
 

Hello, everyone, maybe you can help me.

I have a new Mesu 200 Mk2 and have a problem with tracking: When I slew to a target near the celestial equator (not meridian), to the west, tracking will stop after a few seconds. Sitech.exe will state  the mount status as tracking, and RA/DEC coordinates stay constant. Turning tracking on and off does not help, only slewing to a target further from equator. I would estimate this occurs within about 5 deg. to each side. I am not sure if other sky areas areas are affected, due to bad weather I could only do limited testing. I cleared the horizon file (never touched it). My version of Sitech.exe is 0.94NWin from the Sitech website.

Thanks for any help, Torben


paul K
 

I assume your mount is initialised prior to slew Torben?
Paul


T. van Hees
 

Thanks for helping out, Paul. I initially sync to the west with skyview, then slew and platesolve and sync again. All offset syncs. Skyview shows the correct pointing of the mount. Slewing seems to work fine.


paul K
 

I have a MESU 200 Torben, Let's see what Don / Dan says on this and if it helps I'll share my config file. It might well be different though as yours is the new 200 model.

Paul


On Thu, 8 Oct 2020 at 14:27, <torben@...> wrote:
Thanks for helping out, Paul. I initially sync to the west with skyview, then slew and platesolve and sync again. All offset syncs. Skyview shows the correct pointing of the mount. Slewing seems to work fine.


T. van Hees
 

Hi, and thank you! I have the config file from Lucas Mesu, for my mount. It is different from the original Mesu 200 because there are no encoders (among other things). I am in contact with him, but he suggested to post here, too.

I did nothing but change the location in Sitech.exe. I primarily think there is a configuration problem, but fear something is wrong with the mount. Performance so far (guiding, but also slewing) had been spotty, with the new config file it worked ok. 


paul K
 

I guess you know it stops tracking becasue you get star trails? Could you post the 'mount parms' section of your config?
Paul


T. van Hees
 

Yes, I also think I can hear the RA drive stopping (difficult to tell because the computer fan is noisy). Using start/stop tracking then does not change anything anymore, only after slewing somewhere else. Here you go, and thank you for your help:


Am 08.10.2020 um 17:01 schrieb paul K <paulskirk53@...>:

I guess you know it stops tracking becasue you get star trails? Could you post the 'mount parms' section of your config?
Paul


Jaspal Chadha
 

I got the same mount and had sand issues. After reinstalling software and checking my balance carefully I didn’t have the issue again. 




On 8 Oct 2020, at 16:45, T. van Hees <torben@...> wrote:


Yes, I also think I can hear the RA drive stopping (difficult to tell because the computer fan is noisy). Using start/stop tracking then does not change anything anymore, only after slewing somewhere else. Here you go, and thank you for your help:

<image1.jpeg>

Am 08.10.2020 um 17:01 schrieb paul K <paulskirk53@...>:

I guess you know it stops tracking becasue you get star trails? Could you post the 'mount parms' section of your config?
Paul


T. van Hees
 

Thanks, I will reinstall the software and (quintuple) check balance. 


paul K
 

Here's mine...Why do you have reverse RA guide mode when looking east ticked? That seems odd to me, but I am no expert. Whether the scope is looking east or west, I would want the RA guide mode to be the same. It may not be connected to your problem though.

Another thing I found useful when I had problems initially, was to use Cartes du Ciel (or other) and control the scope using that in daytime. If you offset init pointing west as you mentioned (CWD and scope horiz) that gives you a rough offset inti from Skyview. Now you can slew and track in daytime to add extra opportunity for correcting problems and gathering more info.

Just one more thing which caused me intermittent problems was that I had the incorrect size power plug for my Sitech controller. It worked most of the time. but when the power cable was moved slightly as the mount tracked, it lost connection (which meant the mount lost its initialisation too). There are two industry standard power plugs and both physically fit the controller socket, but only the correct size makes a good electrical contact. I had the wrong one.

I can't remember which is the right size, but I'll search through my posts and find out. I'll post again.
Paul

Sorry I can't think of anything else at present.



paul K
 

There are two sizes of power connector, they are 2.5mm and 2.1mm. The correct size centre power pin for the Sitech II controller is 2.1mm - quote from Don below:

'Hi Paul, the center pin is 2.1 mm.
Don W'

good luck
Paul


T. van Hees
 

Thank you for checking, Paul. I just went outside, and I do have a 2.1mm power connector. The "reverse guide mode" boxes ticked came from the factory configuration, I did not touch this yet. I am not sure why this is needed, but guiding seems to be working so far. 
I see you have version .95G installed, whereas the one from the website is 0.94N. I will try and check out the newest software version, too. Is there any changelog somewhere?


T. van Hees
 

Thank you for your help, Paul and Jaspal. I double checked balance (it was as good as I can get it). Also, I reinstalled the Sitech software, updating to the latest one I found on this forum (0.95G). I found nothing in the changelog that came with it that would suggest fixing a tracking problem. But I just tried it out in daylight and can no longer reproduce the problem, the RA motor keeps doing its thing while tracking. I could only check for a few minutes because the next rain is coming in. Once skies clear up here, I will try again and get back to you with the result. I am cautiously optimistic. You were of great help, thank you.


Don W
 

Hi van Hees,

Looking at your settings for Meridian Limits, you have set them to 90 degrees - that is totally wrong.  It means you NEVER would reach a limit and cause a meridian flip.  Normal settings are like Paul's case - about 5 degrees - you want to limit the range of motion past the meridian so your telescope tube doesn't hit the pier.

The same goes for the Under Pole settings.  They should be set per Paul's settings, or closer to 180°.

Balance is critical, so making sure it is well balanced can make a big difference.

If the RA reading in SiTech stays constant, it is tracking.  If the RA reading is changing, then the mount IS NOT TRACKING, because the world is turning under you.

Don W


T. van Hees
 

Thank you, Don,

the settings are from Lucas Mesu. I have a bent-knee pier which allows my scope to do full turns without hitting anything, i. e. no meridian flip necessary. Of course no endless revolutions are possible because of the cables. When I upgrade to a larger scope I will certainly change these limits. But first, tracking needs to work. If you think these could affect tracking, I will change them anyway.

I triple- and quadruple-checked balance. The new Mesu mount allows to unclutch the Motors for balancing, which makes it much easier. I needed very good balance to use the RC8 on a Heq-5.

My problem was that RA display was staying constant, Sitech.exe showed „Tracking“ as a status, but the mount did not track. There was no difference in star trails between „Tracking“ and „Stopped“ status. There was no error message. Only slewing to a different location made tracking work again. Another reinstall with simultaneous update seems to have fixed it, but I can only be sure once weather gets better.

Thanks again,
Torben


Am 08.10.2020 um 19:12 schrieb Don W <westergren@...>:



Hi van Hees,

Looking at your settings for Meridian Limits, you have set them to 90 degrees - that is totally wrong.  It means you NEVER would reach a limit and cause a meridian flip.  Normal settings are like Paul's case - about 5 degrees - you want to limit the range of motion past the meridian so your telescope tube doesn't hit the pier.

The same goes for the Under Pole settings.  They should be set per Paul's settings, or closer to 180°.

Balance is critical, so making sure it is well balanced can make a big difference.

If the RA reading in SiTech stays constant, it is tracking.  If the RA reading is changing, then the mount IS NOT TRACKING, because the world is turning under you.

Don W


Don W
 

Hi Torben,

It sounds like you had your clutch unclutched when SiTech reported it was tracking, but was not actually moving.

Don W


T. van Hees
 

Hi Don,

no, that was not the case. I would slew close to the equator (actually, to the propeller nebula, to be exact), and then tracking stopped after about one minute. Slewing to another point further away from equator would allow tracking again. Also, when tracking stopped, there was no noise from the RA motor. I did not touch the scope between the slews. I had this problem on two nights out of two so far. The upgrade seems to have solved it, I don’t know why. Between checking for the error, upgrading, and checking again I only touched the DEC clutch to check for balance.

Torben

Am 08.10.2020 um 19:49 schrieb Don W <westergren@...>:

Hi Torben,

It sounds like you had your clutch unclutched when SiTech reported it was tracking, but was not actually moving.

Don W



T. van Hees
 

Hello,

I had some clear skies tonight, and reinstall and upgrading of the software has solved the tracking issues. 

Thank you for your help,
Torben


Jose Ignacio Sanchez Rodriguez
 

Hello Don,

I have a Mesu 200 MKII since october last year and it has performed very well until now. This weekend I started experiencing tracking issues of the sort reported by users like Torben van Hees. The mount is tracking and guiding below 0.5 arcsecs but I get star trails on the sides of the images. At some point during the night the guiding error in RA went completely haywire. I checked for a pier crash of tight cables, but everything was ok.

Based on the post on this thread I have tried to reproduce these issues trying to control for the power source and the temperature (this weekend has been the coldest one I have operated with this mount). So I tried both with a 12V 4 Amp PSU and a 13.8 V 6 Amp one. Both cases at a confortable 20 Celsius indoor temp. The issues I observer happen irrespective of the PSU used.

I am using a 10 kg rig with a 6.5 kg counterweight and the balance as good as I can get it. 

I also took away the trough the mount cabling to control for physical explanations not related to the mount itself.

I initialised the mount with SkyView as I normally do and slewed to a position similar to the one I noticed these issues during the weekend. I let the mount track and from time to time moved it in RA with the hand control. What I observed was that while SiTech.exe always showed "Tracking", at some positions the SiTech.exe RA reading had a slight oscillation. It did not stay still. At other positions it stayed still. 

This is the same behaviour I observed during the weekend tha led to the star trails.

I still need to reproduce the behaviour of the diverging RA guiding error. That I will try to do as soon as I get a clear night.

But for the time being I would like to know your opinion about the oscillating RA reading. Below you may find a dropbox link that contains 5 files:

- 60secLumTrails.fit
- 60secLumTrails.jpg
- a short movie of my test today
- The tracking info log during my test today
- The PHD2 log file of the weekend session until the RA error went through the roof.

https://www.dropbox.com/sh/o20qt54454bdv4a/AACBAMbcOZlxH1J0Rr2vEP8_a?dl=0

The fit and jpg files are pixinsight´s aberration inspector´s result where you can see the star trails on the corners of a 60 sec Lum exposure. You can see the RA reading oscillation in the movie. While last weekend the SiTech tracking info log was not enabled, I enabled it today. As far as I can read it it shows tracking errors, but I am not familiar with this file.

I am of-course also in contact with Lucas Mesu regarding this issue, but would like to know if someone in the forum can shed some light on it.

Thanks in advance,

Jose


paul K
 

the orientation of the trails in the jpg image is very interesting, in which area of sky was the exposure taken?
Paul