autoguiding problem-any suggestions appreciated

[seeker372011 (Narayan)]

I have autoguided my CG5 -my dark site mount- for years now, but the last couple of times I have made it to a dark site this year, it has failed me on both occasions

problem seems to be only in Dec

any suggestions?

i have tried the usual- changing the balance so its rear heavy (slightly) but it just doesn't seem to work

responds fine to the hand controller-slightly sticky but that was always the case...what could suddenly have changed?

what else can I try?

I am using PHD and always have ever since I migrated from Guidedog

thanks for any suggestions

[richardo (Rich)]

Narayan,
every mount needs some attention at some stage.
Dec it seems to me is usually where things tend to start failing.
I had two vixen mounts way back and at least once a year, I'd pull them down and inspect everything.
Usually I'd regrease at least.
The Vixen GP, GP DX mounts had this horrible sticky type grease with little or no viscosity, after a while it becomes hard and glue like.....
You might find regreasing is all it needs.... but as these mounts are mass produced, don't be surprised to find things have worn.

These days with hyper kits and things for the CG5's & 6's it is a simple matter of buying the kit. There are guys with step by step instructions as how to do the part replacements.

Hope this helps.
Good luck with sorting it out.

Rich

[gbeal]

Difficult to tell with not too much info Narayan, but maybe Rich has a point, stickiness. Is it temperature related, same sort of time of year (cooler making whatever is lubing your mount go harder).
It could be an opportune time to pull it to pieces and give it a birthday anyway.
Gary

[gregbradley]

When you say does not work can you be more detailed? Do you connect OK with your mount?

Does your guide camera connect ok and is taking exposures?

Can you do NSEW moves from the controlling software showing cables are all working and everything connected?

Just a guess but I'd hazard a guess saying its a cable problem. Is a cable damaged or a plug damaged - trodden on/dirty?

Have some debris settled on the gears? Are these exposed at all?

What guide camera are you using?

Occasionally I have had a failure that was as simply fixed as pushing the autoguiding plug harder into its jack on the mount.
It had been dragged on by cable weight and pulled out a fraction breaking contact. Hence the focus screen test where you move it using software (not hand controller which is hardware) NSEW so you know commands are reaching the mount.

Greg.

[seeker372011 (Narayan)]

Originally Posted by gregbradley

When you say does not work can you be more detailed? Do you connect OK with your mount?

Does your guide camera connect ok and is taking exposures?

Can you do NSEW moves from the controlling software showing cables are all working and everything connected?

Just a guess but I'd hazard a guess saying its a cable problem. Is a cable damaged or a plug damaged - trodden on/dirty?

Have some debris settled on the gears? Are these exposed at all?

What guide camera are you using?

Occasionally I have had a failure that was as simply fixed as pushing the autoguiding plug harder into its jack on the mount.
It had been dragged on by cable weight and pulled out a fraction breaking contact. Hence the focus screen test where you move it using software (not hand controller which is hardware) NSEW so you know commands are reaching the mount.

Greg.

Greg

I connect Ok and guide ok in RA

I use PHD so I cant test a NSEW move with software (doesnt have a controller) but I can actually see the software firing impulses -but seemingly not enough so it slowly drifts-occasionally it holds for two or three minutes then starts to drift and then its curtains. maybe i can find some other software with a virtual keypad

the guide camera is an Orion Deep Space Imager

I will check it once again-especially that Dec cable-now that you mention it, I now recall once in the past just pulling it out, reversing it and plugging it in, made it work

maybe clean the connectors with isopropyl alchol

if that doesnt work its off to the knackers with this old work horse-well at least a tear down and rebuild

thanks

[gregbradley]

Yeah if its losing the battle with the errors and it is trying then it is fighting something the autoguiding cannot keep up with or it the mount is in fact not getting the corrections (cable).

Greg.

[danielsun]

You may have to increase your DEC calibration steps to 750 or more.
look here.http://www.iceinspace.com.au/forum/s...ad.php?t=58636 at post#63.

Hope this helps.

Cheers Daniel.

[mithrandir (Andrew)]

What's the guide scope? I have an ST80 on my C8 and CG5-ASGT and I have the PHD calibration step set at 2000. Shorter scope, longer step.

I try to get the dec balance really close, and the RA slightly east heavy.

I see you aren't far from here. You might consider dropping in on SNAG some Friday nights.

[seeker372011 (Narayan)]

OK here's the update

at least to me it seems a mechanical problem

I looked at a star through a 12 mm eyepiece while I used the 4 directional keys
when I used the left horizontal, I found the star still continuing to drift even after I stopped pressing the key
I am autoguiding right now -set the anti backlash Dec positive to 55-but it is still gently drifting-over a thirty minute period

(all other anti-backlash set to zero)

[seeker372011 (Narayan)]

Originally Posted by mithrandir

What's the guide scope? I have an ST80 on my C8 and CG5-ASGT and I have the PHD calibration step set at 2000. Shorter scope, longer step.

I try to get the dec balance really close, and the RA slightly east heavy.

I see you aren't far from here. You might consider dropping in on SNAG some Friday nights.

actually I have always believed in having a guide scope with a longer focal length than my imaging scope-in the minority here though I think Eddie Trimarchi does the same, so at least one other person in the universe believes the same,especially when using a cheap mount- my guide scope is 900 mm focal length, i am imaging at 480 mm

what is SNAG????
will gladly come around on a Friday night

[seeker372011 (Narayan)]

further update

I had the anti backlash dec positive set for 55 and that drifted over 30 minutes so I upped it to 60-and it has been guiding for twenty minutes so far in Dec, so who knows I may have hit a sweet spot

still believe the mount needs some mechanical TLC, but with any luck I may be able to actually get an image tonight-touch wood
will the first since March with this Mount!

shooting 10 minute subs in H alpha

[seeker372011 (Narayan)]

spoke to soon-I should bite my tongue
20 minutes and then it drifted off again

it really is a problem with the gears I supsect
I should not have to battle this hard

oh well keep trying till midnight till the Socceroos kick off and then I give up

[mithrandir (Andrew)]

Originally Posted by seeker372011

what is SNAG????
will gladly come around on a Friday night

Sydney Northwest Astronomy Group. A small group of us who meet on Fridays at Dural Pony Club. Ken (solissydney) started it. He's away at the moment. PM for more info.

[seeker372011 (Narayan)]

now trying a dec positive antii backlash of 58

[seeker372011 (Narayan)]

nope,no luck...think a tear down may be the only real solution

[seeker372011 (Narayan)]

tried a half dozen settings in anti backlash-no luck

[seeker372011 (Narayan)]

gave up -finally got one hour of data on IC4628

http://www.flickr.com/photos/9178472...53140/sizes/l/

if only the mount had continued to behave ...