Mesu Mount problems- jumping in RA

[Zakalwe]

OK, so I am having big problems with the Mesu mount. From the start I have had issues with the mount "jumping" in RA

Then the RA rate started to drift, which I think that I've sorted after weeks of faffing about

 

Last night was the first time in ages that I've been able to do and DSO imaging and the damn thing is jumping again.

So far I've:

• changed power supply. The mount now has it's own dedicated Maplin PSU
• removed any USB hubs. The mount is now directly connected to the PC
• changed USB cables
• reinstalled the software
• Upgraded to the latest SiTech firmware
• changed the PC
• To rule out software I've disconnected PHD from Sequence Generator Pro and am running guiding as standalone.
• The balance is good, no snagging cables. 

The polar alignment is spot on (verified with PoleMaster). It will guide OK then randomly will jump, causing the guiding to error.  I then have to halt the sequence and re-centre.

The last thing that I can try is powering the mount off a battery, though I'm not convinced that will make any difference. After all it's been powered by two totally different PSUs. It jumps when it's not being guided, for instance when doing Lunar or Solar imaging.

I cannot think of anything else to change or alter. Any ideas guys?

 

 

[Davey-T]

How long between jumps or does it just do one and then run OK ?

Dave

[StuartJPP]

Probably unrelated but I had a similar problem with my Avalon mount except that it used to move randomly in either RA or DEC. I narrowed it down to not plugging in the hand controller. The inputs must have been "floating" with nothing connected.

The solution was a firmware update where I suspect they enabled pull-ups on the inputs to the microcontroller for those pins.

The same could possibly happen with the guide port inputs.

 

[steppenwolf]

Quote

The last thing that I can try is powering the mount off a battery, though I'm not convinced that will make any difference. After all it's been powered by two totally different PSUs. It jumps when it's not being guided, for instance when doing Lunar or Solar imaging.

I run mine on a Maplin PSU without any issue so I'd be very surprised if this was the issue.

What Scope Encoders mode are you running in, Polite, Ignore or Precise?

Have you been standing by the mount when it has happened - if so, what did you hear?

Something to check - loosen the terminal screws of the Sitech controller connection strip one at a time, remove the wire, push it back in and tighten the screw again. Do this for all the connections to ensure that nothing has come loose.

Hide the sledgehammer

[Zakalwe]

The jumping is random. It can track for  while and then jump.

@Steve...it's been set up as per your very useful setup guide. I can't remember offhand what the encoders are set at...I'll check and come back to you, but they should be exactly  as per your document.

The sledgehammer is out of reach.

For now........

 

[Zakalwe]

1 hour ago, StuartJPP said:

Probably unrelated but I had a similar problem with my Avalon mount except that it used to move randomly in either RA or DEC. I narrowed it down to not plugging in the hand controller. The inputs must have been "floating" with nothing connected.

The solution was a firmware update where I suspect they enabled pull-ups on the inputs to the microcontroller for those pins.

The same could possibly happen with the guide port inputs.

 

Thanks Stuart...I've upgraded the firmware to the latest SiTech version.

[Zakalwe]

I've heard the mount motors jumping as it's done it when I've been standing beside it. It's almost as if the handcontroller has been used. I'll try unplugging the handset.....I've not tried that yet.

To be honest, I don't use the handset as one on the buttons is a bit hit and miss. You've given me something else to try.

[StuartJPP]

Good luck, I could hear the motors on mine moving sightly, it tended to be worse between subs which I suspect was when there was image data being downloaded over USB.

Steve's suggestion regarding re-seating the wires is a good one, along with hiding the sledgehammer...

[Davey-T]

I had a dodgy handset on the iEQ45 the forwards RA button would suddenly start moving the mount without touching it , a quick wiggle and it carried on as normal.

Dave

[nigelg]

I had a similar problem with mine. It showed up in SGPro while trying centre the target and not getting within 200 pixels.

I had set the encoders to Polite mode, but because my Tick count was not accurate the encoders were arguing, causing the mount to oscillate.

Changing the encoders to Ignore I can now centre in two iterations to sub pixel.

 

Nigel

[Zakalwe]

22 hours ago, steppenwolf said:

What Scope Encoders mode are you running in, Polite, Ignore or Precise?

Have you been standing by the mount when it has happened - if so, what did you hear?

Something to check - loosen the terminal screws of the Sitech controller connection strip one at a time, remove the wire, push it back in and tighten the screw again. Do this for all the connections to ensure that nothing has come loose.

Hide the sledgehammer

The encoders are in Polite mode.

I'll check the wiring..good shout.

[steppenwolf]

Polite Mode should be fine - it allows small movements (set by the threshold value) to be made without involving the secondary encoders. This mode is ideal for autoguiding as it avoids sudden large correction from the secondary encoder combating the guide correction.

[tomato]

Did disconnecting the hand controller help, it might be this if you have some dodgy switches inside the case?

No consolation I'm sure, but I have  lugged my Mesu in and out of a flight case for every session for the last 2 years with no issues to date (touching lots of wood), so there must be something amiss.

Hope you get it sorted.

 

[Horwig]

Don't have a Mesu, but I do use the SciTech controler. Had a problem with mine a while ago, it would do random moves in RA, turned out to be a dodgy optical encoder on the RA  drive motor, swapped it out for a spare encoder, all well and good since.

Don't know if this is of any use.

Best of luck in finding the problem, the intermittent ones are blooming hard (replace with own choice of expletive).

Huw

[Zakalwe]

OK, here's where I am up to with this issue.

I've upgraded the firmware to 0.91Xd. There are reports on the Yahoo SiTech page that a number of earlier releases were causing spikes during guiding. 0.91Xd also "cures" the issue of the mount moving after issuing an initial CalStar Init.
To eliminate power problems I've used a 12v lead acid battery to power the mount.
Sequence Generator Pro is used for plate-solving and camera control. I've removed the PHD details from SGP to remove any issues there.
PHD2 is pulse guiding the mount.

The mount's USB goes directly to the control PC. It does not run through a USB hub.

I set it up tonight, let the mount settle and started guiding. After a couple of minutes I've had a massive spike in RA:
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I then re-calibrated and ran PHD's Guiding Assistant. This disables the guiding commands and monitors the mount's tracking and polar alignment. After about 1 minute I had another RA spike.

I then change the RA encoder to Ignore. DEC is still on Polite. I set the mount off guiding (no image sequence are being taken during these test, so there's no chance of the USB bandwidth being saturated). The mount guides OK for about 12 minutes, then PHD starts pinging a "guidestar lost" error. The mount has jumped again.

I've checked the wiring and I cannot see anything loose. I'm suspecting either a bad connection somewhere, a dodgy controller or a dodgy motor or encoder.

Any other ideas?

[swag72]

How are you doing on diagnosing this issue Steve? Have you spoken with Lucas at all to get his ideas on it?

[Zakalwe]

14 hours ago, swag72 said:

How are you doing on diagnosing this issue Steve? Have you spoken with Lucas at all to get his ideas on it?

Hi Sara,

Ive got a custom firmware loaded into the SiTech now that Dan at Sidereal Technologies has created. This firmware has extensive logging capabilities which should help to identify the problem.
The problem is that its been cloudy/raining/foggy here for the last 3 weeks so I haven't had a chance to test it.  There's another chap on the Mesu Yahoo group reporting the same problem too, so it's not unique.

[swag72]

Have you calibrated your PC clock to Sitech? And also set the clock not to update?

 

[Zakalwe]

3 hours ago, swag72 said:

Have you calibrated your PC clock to Sitech? And also set the clock not to update?

 

Yes, but not tested it. SiTech seem to think that this could be an issue.

It has been suggested to buy a network time server...sounds like overkill to me!

[swag72]

I went through this today with a friend of mine on teamviewer.... It involves syncing your PC clock to the internet, switching off automatic syncs, then syncing to sitech...... I can show you on team viewer if that would help

[Zakalwe]

3 hours ago, swag72 said:

I went through this today with a friend of mine on teamviewer.... It involves syncing your PC clock to the internet, switching off automatic syncs, then syncing to sitech...... I can show you on team viewer if that would help

That's very generous of you Sara, thank you. Was your friend having a similar problem?

I know how to turn off the NTP synching....the bit that I am unclear on is syncing to SiTech. How is this done? Also, I seem to remember that you shouldn't sync until SiTech has been running for at least an hour....is this true?

 

[swag72]

Yes he was - Having a jump in RA at fairly regular intervals.

OK.... so sync the PC and then untick the automatic sync. As you say you need to have the mount running for at least an hour prior to this.

Below I've attached a screen grab of the next step.

1) Click features

2) Click offset track rates

3) Click resync (That's resyncing the Sitech to the PC clock)

4) Click Save ServoCal

You can keep your eye on this Offset tracking rates window when guiding. Apparently the numbers showing at the bottom if the screen (diff between comp time and scope time) should stay pretty low. If they go above 50 then in your next sub break just run through this whole process again of resetting the PC clock and syncing to the Sitech. This has come from a friend of mine who spoke with Dan about it at Sitech and he said that this was a fix until they bought out a software update.

Hope that helps

 

[Zakalwe]

You're a star, Sara, thank you

I'll give this a go (assuming it ever clears here.It's currently blowing a hooley out there). I'll be delighted if this is all it takes to correct this problem. At the same time I'll be incredibly frustrated......why does the end-user have to muck about in the blood and guts of the system just to use the gear??

[Zakalwe]

Hmmm....Ive powered up the mount and PC. Synced the PC clock and unticked the Internet time update. I set the mount tracking by doing an Offset Init. As soon as I do an Offset Init the "Diff Between Computer Time and Telescope Time" starts climbing. I thought that this should hang around 30Ms?

[swag72]

I don't do an offset init..... I unpark my scope and it automatically starts tracking... I've set that in the config