Synscan pointing accuracy way off.

Skyhawk (Justin) · #1 10-07-2013, 02:58 PM

A little while back I bought the SKEQ5GOTO system for my EQ5 mount.It's worked perfectly and done its job. However I updated the firmware on the hand controller to V3.35 and now it's pointing accuracy is way off. After performing a decent polar align without the unit, I then switch it on and make sure everything is entered correctly. The first alignment star was Hadar and the scope slewed towards Achenar instead. After resetting the unit a few times I managed to get a successful 3 star alignment even though it slewed way off target each time. Entering an object in the hand controller slews the telescope in the general direction of the object but is nowhere to be found around the field of view.

Do you guys have any idea what is causing this, also where can I find an older version of the firmware, say 3.27 as I would like to reflash the handcontroller and see if it's a firmware issue. Also do I need to upgrade the firmware in the motor board?

Appreciate the help.
Thanks

Merlin66 (Ken) · #2 10-07-2013, 03:38 PM

Justin,
The V3.27 is still available for download on the Skywatcher site.
I don't think you need worry about the firmware.
I'm still using V3.27 - never bothered about the upgrade.
If it was working well before - it should do the same now.....

LewisM · #3 10-07-2013, 03:43 PM

I have 3.35... UNFORTUNATELY.

If you watch through the eyepiece or liveview, it will slew EXACTLY on target, then slew away, then back on, then away and so forth for 4 or 5 iterations, before finally ending up OFF target.

I reinstalled 3.27. It's the only one that works PROPERLY.

Astro_Bot · #4 10-07-2013, 03:44 PM

Double check the usual - date, time, location, timezone (make sure the +/- sign is correct), daylight saving. Although unlikely, is your tripod tilting on a soft surface? I can't help with v3.35 as I still use v3.27.

Steffen · #5 10-07-2013, 04:05 PM

Quote:

Originally Posted by LewisM

If you watch through the eyepiece or liveview, it will slew EXACTLY on target, then slew away, then back on, then away and so forth for 4 or 5 iterations, before finally ending up OFF target.

Same here. It does this in Dec only, BTW. If you push a Dec button to move back to the object but overshoot it for a degree or so, then hit enter again to GOTO the object it will get it right. Definitely a software bug.

From preliminary testing this only seems to happen after 3-star alignments. I've never seen this after a 2-star alignment. Hence, if your cone error (sorry Gary, forgot the proper term again) is low don't bother with 3-star alignment.

Cheers
Steffen.

Skyhawk (Justin) · #6 10-07-2013, 05:04 PM

Thanks for the help guys.
I double and triple checked my co-ordinates, time and date and the mount is on my patio, so a solid brick paved surface.
Tell me, the time zone is that your time + from GMT, because that could be an issue, Cape Town geographically falls into GMT + 1, however we take our time as GMT +2 to tie in with the rest of the country.

I have found 3.27 online and will attempt to flash the hand controller back to 3.27, the whole Polaris positioning in the setup freaks me out anyway. Why is nothing designed for us Southern Hemisphere guys?

I have noticed the 4 or 5 iterations after slewing to a target, also found it kinda weird.

rustigsmed (Russell) · #7 11-07-2013, 12:30 AM

Quote:

Originally Posted by Skyhawk

A little while back I bought the SKEQ5GOTO system for my EQ5 mount.It's worked perfectly and done its job. However I updated the firmware on the hand controller to V3.35 and now it's pointing accuracy is way off. After performing a decent polar align without the unit, I then switch it on and make sure everything is entered correctly. The first alignment star was Hadar and the scope slewed towards Achenar instead. After resetting the unit a few times I managed to get a successful 3 star alignment even though it slewed way off target each time. Entering an object in the hand controller slews the telescope in the general direction of the object but is nowhere to be found around the field of view.

Do you guys have any idea what is causing this, also where can I find an older version of the firmware, say 3.27 as I would like to reflash the handcontroller and see if it's a firmware issue. Also do I need to upgrade the firmware in the motor board?

Appreciate the help.
Thanks

Appears to be doing the same thing with the eq8 which I think is 3.33 looks like I won't bother with 3.35 and go backwards

Skyhawk (Justin) · #8 11-07-2013, 01:06 AM

Well I've now installed 3.27 and looks like I'll only be able to test it our tomorrow night.

Skyhawk (Justin) · #9 12-07-2013, 09:56 PM

Well, 3.27 is back on and the scope is tracking like a dream again

Thanks for the help!

jakob · #10 13-07-2013, 06:28 PM

I have noticed the overshooting too.
I have measured the backlash and entered the values in the system.
(on my HEQ5 the backlash in Ra is 0' 36" and Dec axis 1' 5")
Now there is no overshooting now and the pointing accuracy is ok.
So I'm happy V3.35.

I guesse the servo algorism is a bit more agressiv (faster pointing) than in the previous release.

Skyhawk (Justin) · #11 13-07-2013, 07:10 PM

That's good to hear.

Well guys, I've studied those website links you posted and theoretically I understand polar alignment better than ever, that tutorial is brilliant. I even ran the simulator and nailed it. For the first time ever I really feel confident that I can get my polar alignment nice and accurate. I've always battled with drift alignment but now I know why!
Can't wait to get out there...my luck it's raining here today!

I also downloaded alignmaster and have it talking to the telescope nicely through ASCOM.
Now to just to try it.
Big thanks to all you guys for the input, it really helps!