Help with EQ6R Pro with RA periodic oscillation

[Diego Montes Muñoz de Verger]

Hi guys.

I have a periodic oscillation in my new EQ6R PRO mount every minute and a half approximately in RA.

I've been searching the forum for several days and can't find anyone with a similar error

Here are the logs with calibration-guiding-meririan flip (with APT)-calibration-guiding

https://openphdguiding.org/logs/dl/PHD2_logs_0JoG.zip

at the end of the session many clouds appeared but I was already sleeping

I have a EQ6R pro+ED80+ASI183mm as main

EZG-60+QHYIII290 as guiding solution.

APT with EQMOD

I thank you for the help 

[Brian Valente]

Hi Diego

sorry to see you're having problems

it looks like something within the mount or your setup. Here's the raw RA performance:

you can see there are nearly instantaneous moves up to 20" that PHD won't be able to handle well. 

Your PHD calibration isn't quite orthogonal but i would not expect that to create this kind of problem

you could also do a guiding assistant run just to get some more feedback on settings. but again, these are small things unrelated to your RA issue here.

I'd say your best bet is to consult an EQ/EQMod forum or talk to the manufacturer. 

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Brian Valente

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[peter wolsley]

Diego,

I am no expert but I have seen several users experiencing RA spikes that were identified as being due to having a "Rowan belt mod" installed in their mount.  If you search this forum for "Rowan belt mod" you can learn more.  The solution was to ask the vendor for a modified gear.

I may be way off base on this guess.

Peter

On Monday, September 9, 2019 at 11:04:59 AM UTC-4, Brian Valente wrote:

Hi Diego

sorry to see you're having problems

it looks like something within the mount or your setup. Here's the raw RA performance:

you can see there are nearly instantaneous moves up to 20" that PHD won't be able to handle well. 

Your PHD calibration isn't quite orthogonal but i would not expect that to create this kind of problem

you could also do a guiding assistant run just to get some more feedback on settings. but again, these are small things unrelated to your RA issue here.

I'd say your best bet is to consult an EQ/EQMod forum or talk to the manufacturer. 

On Mon, Sep 9, 2019 at 2:06 AM Diego Montes Muñoz de Verger <di...@unielectrica.com> wrote:

Hi guys.

I have a periodic oscillation in my new EQ6R PRO mount every minute and a half approximately in RA.

I've been searching the forum for several days and can't find anyone with a similar error

Here are the logs with calibration-guiding-meririan flip (with APT)-calibration-guiding

https://openphdguiding.org/logs/dl/PHD2_logs_0JoG.zip

at the end of the session many clouds appeared but I was already sleeping

I have a EQ6R pro+ED80+ASI183mm as main

EZG-60+QHYIII290 as guiding solution.

APT with EQMOD

I thank you for the help 

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[Diego Montes Muñoz de Verger]

Thanks for your help. It is a new mount so I will first rule out that it is an EQMOD problem

[bw_msgboard]

You should do what makes sense to you on problem isolation, it’s always good to be sure about things.  But a couple of data points:

 

1. EQMOD is used by many hundreds of users who don’t have these problems.  Assuming you’ve done the settings according to the link below, it’s highly unlikely to be an application-level s/w problem.
2. The EQ mounts, like many others of their type, frequently have manufacturing, assembly, and initial-delivery problems.  We have seen many of these things over the past years, including some just like yours, and they invariably require mechanical corrections of some kind.

 

https://github.com/OpenPHDGuiding/phd2/wiki/EQASCOM-Settings

 

Hope you can get it resolved quickly.

 

Bruce

 

 

 

 

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[John Sim]

Hi Diego

I have the same mount but I haven't had a chance to use it yet. Like you I've been following forum threads about it and I haven't seen any similar reports. I have a couple of suggestions:

First, Skywatcher recently released new firmware for the motor controllers in the EQ6R, for the newer versions of the mount that have the USB port. The release notes for the firmware don't mention fixing any issue like yours but it is probably worth updating anyway. You can download the firmware from the Skywatcher website. 

Second, try removing the cover over the RA belt drive (at the bottom of the mount head where the counterweight bar is, secured by 3 small screws). There's a small gear connected to the stepper motor which belt drives a large gear connected to the worm. That's it, pretty simple. Check for anything obviously wrong. Set the mount tracking and watch closely for at least 2 minutes so it covers one of the RA spike events, perhaps you could even make a video. You can even do this indoors in daylight, you wont know when the spike actually occurs but it may be obvious.

A visual inspection of your logs shows RA spiking around every 110 seconds. PHDLogViewer's frequency analysis of your 4 hour session doesn't show any spike around 110 seconds but there are very clear and quite significant spikes at 54.6, 36.4, 27.3, 21.8, 18.1, 15.6 and 13.6 seconds. Each of these frequencies is nearly an exact harmonic of 109.2 seconds, so every 109.2 seconds they would combine into a giant spike. I don't know what that 109.2 second frequency is associated with. The worm period is 480 seconds and the stepper gear's period is 120 seconds (and so a harmonic of the worm period).

Perhaps this will ring a bell with someone and there will be an easy fix, however I suspect you may have to escalate to your vendor or Skywatcher.

Good luck

John

[Diego Montes Muñoz de Verger]

I'm sorry for taking a while to respond. I've been working a lot and I wanted to try all the stuff before I wrote

 

I've updated the engine driver to the latest version 3.4.23. No change in the problem

I opened the RA gear cover but I haven't seen anything weird with the pulley. I'm not an expert on this issue.

To rule out problems with EQMOD, I tried to do a guide with the native ascom driver but did not recognize any COM port. If it works right with SynSCanPro for Windows

I consulted on the EQMOD forum and they tell me that the errors I have have have nothing to do with EQMOD

I've checked the EQMOD parameters and I think they're all right like https://github.com/OpenPHDGuiding/phd2/wiki/EQASCOM-Settings

I think it's a mount problem. The mount has two months, can come from the factory with "Rowan belt mod" installed?

I put a new log with guiding assistant as you requested me

Thank you all for your help. I'm a little lost and I don't know what to do

https://openphdguiding.org/logs/dl/PHD2_logs_F4H9.zip

[Bruce Sutherlin]

I have a similar issue with RA tracking. I want to rule out PHD2 and Svbony 105 guide camera being the issue before telling Skywatcher to repair my mount. The RA looks like a square sine wave and I get occasional pulseguide error warnings in PHD2. Not sure how to paste image here on my phone

Bruce Sutherlin
EQ6R Pro purchased Nov 2018

[peter wolsley]

Bruce,

We always ask that you upload your guide and debug logs so that we can look at the data.  There is a feature in PHD2 for uploading these logs.  The more info you can provide the better answers we can offer.

Peter

I would also suggest that you start a new topic for your issue.

[Bruce Sutherlin]

I’ve just joined the forum so I’m a little slow. I upload through the PHD2 software? And I can post a new thread if that helps.  

Sent from my iPhone

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[Brian Valente]

Hi Bruce

 

Yes under the Help menu there’s an option

More details are here: https://openphdguiding.org/getting-help/

 

 

Thanks

 

Brian

 

portfolio https://www.brianvalentephotography.com/

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[Bruce Sutherlin]

Great! Will do!

Sent from my iPhone

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[Andy Galasso]

Hi Diego,

We can see from the guide log that the unguided RA tracking has a periodic error of about 40 arc-seconds peak to peak and a period of about 480 seconds.  In addition to the smoothly varying 480s error, there is a rapid spike of about 6" that occurs about every 120s.  The 120s spike is actually the biggest problem for guiding since it happens so quickly that it cannot be guided out.

I hope this information will be useful in helping to identify the underlying mechanical issue.

BTW, you can create these graphs yourself with PHD2 log viewer, or with EQMOD PecPrep.

Andy

[John Sim]

Hi Diego

Don't be confused by the "Rowan belt mod". This applies to earlier versions of the EQ6 series of mounts which, from the factory, have only gears like a clock to drive the RA axis. Your mount, the EQ6R Pro, is belt driven.

Re Andy's post, the 480 second period oscillation is the worm period for the mount. It's normal (although seems to be a bit large) and PHD2 will correct it and/or you could use one of the periodic error curve correction tools to correct it. However that 109 second oscillation is still there and cannot be guided out. I agree with you that there is something wrong with the mount. Can you get support from your vendor? If the cannot explain it and provide a solution then they should replace the mount.