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

Chris H.

Good to hear you got it sorted out, Parijat!


On Fri, May 4, 2012 at 3:03 AM, photonphisher <parijat_singh@...>wrote:


Progress at last!

I took the 3 gears out from the RA gearbox, cleaned thoroughly and placed
them back. Did not see any noticeable dirt in there but cleaned all of them
re-greased anyway.

And just completed running several hours of tests in PEMPro, imaging and
guiding. So far, the issue has not come back. So either there was something
in the gear teeth (which I could not see) or old grease, or the act of
taking the gears out and assembling back with the pinions. Not sure but the
issue seems to be gone now! :)

Thanks to all who responded with ideas and suggestions...
I think the gears might need more maintenance perhaps than just lube,
maybe cleaning once in a while.


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

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
This only happens one time per worm cycle?

--- In ap-gto@...<mailto:>, "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@...<mailto:>, "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@...<mailto:>, "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@...<mailto:>, 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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