ASCOM Device Hub and ldx75 mount

[rick...@gmail.com]

In learning howto use PHD2 I (like others) have made a few mistakes.  Once figured out it worked great even with the boat anchor for a mount I have. I purchased a used AR 152 telescope that came with a Meade ldx75 mount.  First let me say upfront I know the mount is not rated to handle the weight of the 152 but it does work.  I had to set it up in ASCOM with a POTH hub, and it worked quite well to allow me the get longer exposure times.  Then I updated ASCOM to the latest version which did away with POTH in favor of the new Device hub. I loaded everything in and after fixing a few bugs had everything communicating. Next I opened PHD2 and tried to calibrate it.   After a few attempts and an adjustment to the exposure time it worked and the guiding was perfect.  Last night I had an imaging plan,  set up the equipment and slewed to my target.  After more than 3 hours of trying to calibrate PHD2 the battery on the computer finally died putting an end to  my frustration.  Each time the error message was the same.  The star did not move enough in the dec backlash clearing. 

PHD2 worked reasonably well before I did the update to the latest version of ASCOM.  Now it does not.  It will not complete the calibration. I looked at the log and it shows all the movements, the completion of the RA calibration, and then the failure of the Dec.

Any advice (other than lose the boat anchor) would be greatly appreciated.

Rick

[Bryan]

Rick

Please post both Guide and Debug logs.

Bryan

[rick...@gmail.com]

Here they are as requested

Rick

[bw_msgboard]

Hi Rick, sorry you’re having problems. As you know, the driver/mount is simply not responding to pulse-guide commands in the way it should.  Here’s a typical calibration result:

 

 

 

Dec is in green, so it should produce a line that is roughly perpendicular to the RA line in red.  You haven’t said what your guiding assembly looks like, so I have to assume the guide scope focal length really is 170mm.  Even the RA results don’t look right – the computed rate of movement is about 6.2 arc-sec/sec but the driver is reporting the guide speed in the mount is 15 arc-sec/sec (1x sidereal).  I think you’ll have to go back to basics here and then try to get help from the ASCOM device hub author.  I’d recommend running the Star-Cross test in PHD2 or do it manually using the Manual Guide tool.  Nothing is going to work unless you can get the mount to respond in all 4 directions.  For the purpose of calibration, you can manually clear the Declination backlash ahead of time.  Just start looping exposures and use the hand-controller to move the scope north (‘up’ button) until you see the stars on the display start to move.  Your mount may have a gigantic amount of Dec backlash, but that doesn’t mean it can’t be used – but you have to be able to get a calibration.

 

You should read the trouble-shooting section in the PHD2 help guide to sort through these problems, including following the links to the various tools that are available to you.  I don’t think we’ve seen many logs from people using the new ASCOM device hub so there may be problems there with pulse-guiding.  Also, I don’t think there’s anything preventing you from using the old POTH tool from an earlier ASCOM release if you want to try that as a trouble-shooting option.

 

Good luck,

Bruce

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[Guy Brandenburg]

May I state that the PHD2 folks are beyond amazing in their customer support emails? Thanks so much!
Guy Brandenburg

[bw_msgboard]

Thanks for the feedback, Guy.

Bruce

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[Michael 8554]

Hi Rick

I would suggest that you simplify things by ditching POTH or Device Hub until you get things working..

Also try the recently created Autostar 497 ASCOM driver  "Meade Autostar/Audiostar Project (pre-release June 2019)" 

It's on the ASCOM Telescope/Mount Drivers page.

Michael

Wiltshire UK

[rick...@gmail.com]

Bruce,

My guide scope is 190mm.  I have removed ASCOM 6.5 and installed 6.4.  I went through all my software including PHD2 and set them up as POTH hub.  Unfortunately its cloudy again tonight but if I get so much as a hole I will try to calibrate again.  If it works I have my answer.  If not I'm lible to use the boat anchor mount for a boat anchor.

Thanks

Rick

[Guy Brandenburg]

Bad weather has prevented us from doing much. Rainiest summer I’ve seen in many years. 

 But I have spent several hours doing another drift alignment; even tho this is in a permanent observatory, it Seems the pier (or something) had moved by a substantial fraction of a degree. If this does not solve the problem — if the long FL of ouR C-14, even with a focal reducer, Combined with my Dual-chip Sbig ccd, simply does not allow for autoguiding unless I plan and find a nice bright star that I can use, rather close to my target, well then I guess I will probably need to make some fairly major equipment change. 

Guy

Sent from my iPhone, which inserts all kinds of weird punctuation and such just to keep you on your toes

On Aug 16, 2020, at 8:41 PM, rick...@gmail.com <rick...@gmail.com> wrote:



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[rick...@gmail.com]

I had patchy clouds but enough to try and calibrate PHD.  After several failed attempts with the same error message (star did not move enough in dec backlash clearing) it became too cloudy to continue.  It appears the change back to POTH did nothing.  I emailed Meade requesting the information of the sidereal tracking rate of the mount but after 2 days still n reply.  Unfortunately that's no surprise. I am at a loss of what to do or where to turn for help.

 Thanks

Rick

[Brian Valente]

Hi Rick

>>>After several failed attempts with the same error message (star did not move enough in dec backlash clearing)

Can you post these logs?

on this error message, did it stop the calibration, or just report backlash was a problem?

backlash clearing will usually not invalidate the calibration, so you should at least have a working calibration (whether it's any good or not is a different story)

also did you try the star cross test?

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Brian 

Brian Valente

portfolio brianvalentephotography.com 

[mj.w...@gmail.com]

Hi Rick and Guy

It might be instructive to post the Logs for one of your earlier successful sessions.

Also describe how you have the mount, camera, and Autostar handbox connected.

Michael

Wiltshire UK

[rick...@gmail.com]

I only had a complete calibration once and the log is gone as I removed PHD2 from the computer and reinstalled it. The camera is connected by USB with ASCOM Meadecam driver. The mount is connected by USB to the port nn the hand paddle and a POTH hub with the Meade classic driver.  I may have found the problem.  I didn't think about it but I purchased a telescope and mount as a package used.  The scope and all the equipment is 35+ pounds.  The payload capacity f the mount is 15 pounds.  Tonight I will try to attach just my guide scope to the mount and calibrate in PHD2.  If it works I have my answer, if  not I still have a problem. 

Rick

[rick...@gmail.com]

Last night I worked with a couple experienced PHD2 users locally and tried a bunch of changes to the settings as well as bypassing the POHT hub and using the Meade classic driver.  Every time the results were the same.  Star did not move enough in dec backlash clearing. To answer another question, no the calibration does not complete.  It aborts with the error message.  As I said previously I have one more thing to try tonight which may give me an answer.  If not I can always use the mount for a boat anchor and curse the unscrupulous person who sold it to me with the assurance that a 33 pound telescope on a 15 pound weight limit mount works fine. Tonight will tell!

Rick