Re: Need help with issue in RA guiding and Synchronous Pulseguide


Hi Marj,

The moon is up, so I am not in a big hurry right now....and have time to do some more tests.


--- In ap-gto@..., Marj <marj@...> wrote:


Roland and I will be back in the office tomorrow and will review your information at that time. We have been on the road since NEAF.

Marjorie Christen

On May 3, 2012, at 4:28 PM, "photonphisher" <parijat_singh@...<mailto:parijat_singh@...>> wrote:

Hi Marj,
In the tracking curve I had uploaded, you can see PEM was always disabled (red button on the left). So I had ruled that out initially.

I think the gears are something I have not cleaned in a year (only lubricated). They look clean but it I understand from some of the posts here, it is suspect as it does not take much to cause a 5" irregularity.

Thanks again.

--- In ap-gto@...<>, "marjchristen" <marj@> wrote:

I suggest that you disable the PEM first and evaluate the performance. The rest of the steps you mention may not be needed if the problem is dur to an erroneous PEM curve.

Marj Christen

--- In ap-gto@...<>, "photonphisher" <parijat_singh@> wrote:

Hi Marj and All,

Thanks a lot for your valuable suggestions. I now have a good list of things to check and ponder on.

I am planning to remove the 3 gears and carefully clean them well, and apply fresh grease.
Then double check the worm binding, backlash etc.
And disable PEM before checking the tracking.

Some homework to do :)

Thanks again, very much appreciate the help.


--- In ap-gto@...<>, "marjchristen" <marj@> wrote:

Dear Parijat,

Here is another idea. Do you have PEM set to yes? If you do, set it to "no" and see what happens. Sometimes, people create a bad periodic error correction model and then when the correction is activated, it causes strange movement.


--- In ap-gto@...<>, "photonphisher" <parijat_singh@> wrote:

Hi Floyd
Yes it happens once per worm cycle. I monitored it for 5 cycles and showed up exactly at the same location each time. I can only think of the worm/block/assembly but I don't know the internals.

Last night I was seeing dumbells in 30 sec exposures if they fell in the right (or wrong) window. :(


--- In ap-gto@...<>, "bakersfieldbiker" <fblue@> wrote:

Oh, I agree, it was probably not the situation, just was curious.
This only happens one time per worm cycle?

--- In ap-gto@...<>, "photonphisher" <parijat_singh@> wrote:

Hi Floyd,
I moved it 360degrees and it move smoothly with fingers. The mesh is optimum that there is little or no backlash. Also the screw on the spur gear is very tight.
That is the only gear in phase with the worm period and I felt nothing wrong with it physically and moving it full circle. No binding whatsoever. I would think binding would cause an issue much more prominent than 5arcsec.


--- In ap-gto@...<>, "bakersfieldbiker" <fblue@> wrote:

Hi Parijat,
Did you actually move the spur gear on the worm and this is where you say it moves smoothly? Just curious, because of an earlier thread where I described a binding in the worm gear bearing that I found on the AP-900.
Probably not related, but am wondering.

--- In ap-gto@...<>, "photonphisher" <parijat_singh@> wrote:

Hi David,
Thanks for your reply.
I have checked the gears for binding, etc. but they are all smoothly moving. Hence running out of ideas.


--- In ap-gto@...<>, David Holko <dholko@> wrote:


About a year ago I had a issue with my AP1200 RA motor. Howard got on
the phone with me and walked me thru a few checks. I am sure that once
the staff returns from NEAF you will be able to contact Howard and he
will do the same. It is not difficult to remove the top of the RA
housing and see and feel the gears and how the move with your fingers.
To see if there are binding.
I ended up sending the control box, RA housing and cables back to AP and
it all got sorted out. No issues since.


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