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Losmandy GM8 problem...still

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#1 Rolex2

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Posted 07 October 2013 - 10:12 PM

Set the gm8 and Gemini 2 for a great night of viewing. At some point I lose alignment. It does not matter if I align with 1 or 2 stars. Obviously I am doing something wrong. Help would appreciated. Rowland

#2 ErikB

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Posted 07 October 2013 - 11:34 PM

I don't know if you already posted and got some advice, but starting from scratch the first possibilities that come to my mind are:
1. Your clutches aren't tight enough, and one slipped, either because you touched the scope or due to slight imbalance. Since the Gemini normally uses only encoders attached to the motors, when the clutch slips, the motor doesn't turn and the encodes doesn't change its output, so Gemini thinks there has been no movement.
2. You might have a bad contact somewhere in the Gemini or associated cables.

#3 Hilmi

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Posted 08 October 2013 - 02:02 AM

The problem is that you are aligning with only 2 stars. You need at least 3 to the east and 3 to the west. I prefer 4 on each side.

The first star you align to on each side doesn't even get added to the model, it just does an index correction. every subsequent star after that is what actually what gets built into the model.

#4 Raginar

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Posted 08 October 2013 - 09:09 AM

Checks. I'd go to the Tom Hilton website and read through all the pages.

#5 Rolex2

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Posted 08 October 2013 - 11:10 AM

What is tom's website?

#6 Raginar

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Posted 08 October 2013 - 11:14 AM

www.gemini-2.com. It's a must read.

#7 tomcody

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Posted 08 October 2013 - 01:41 PM

I don't know if you already posted and got some advice, but starting from scratch the first possibilities that come to my mind are:
1. Your clutches aren't tight enough, and one slipped, either because you touched the scope or due to slight imbalance. Since the Gemini normally uses only encoders attached to the motors, when the clutch slips, the motor doesn't turn and the encodes doesn't change its output, so Gemini thinks there has been no movement.

Rolex2,
You did not say how much you loose alignment? like just to the edge of the field of view or way off position?
But Eric's advice about the clutch slipping is the first place to check. One thing to remember is that the original Losmandy design called for digital drive and the ability to push the scope to the next target, so the clutches are designed to slip to allow you to push it around. Now along came the Gemini Goto and the clutch slipping was a bad thing as in, it slips and you loose position, not what you want with computer control, so what did Losmandy do? come up with the clutch knobs with three handles or levers on them so you can"really tighten that clutch up" . and no more slipping. Now you do not necessarily need the three handle knobs, but you now know why they are made , and maybe that is what is causing your problem?
Rex

#8 RAKing

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Posted 08 October 2013 - 03:07 PM

Sorry to hear about this. I use my GM-8/Gemini with nothing more than polar alignment and one star. Maybe more stars are better, but I have never had any issues with one.

I also think a slipping clutch might be the culprit and hope it's nothing more serious. (I use the three-prong clutch knobs, too.)

BTW - I also added DSCs to my GM-8 this year because the last time I used this mount at a public outreach session, someone grabbed the eyepiece just a bit too hard and knocked everything out of alignment. With the DSCs connected, my Gemini can always find its way back home. :)

Cheers,

Ron

#9 Raginar

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Posted 08 October 2013 - 03:17 PM

I wish the DSC worked with my Gemini-2...

#10 tomcody

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Posted 08 October 2013 - 04:38 PM

I wish the DSC worked with my Gemini-2...

there is a thread about that, the new high resolution Losmandy kits should be ready in a couple weeks, then Rene may activate that function in the Gemini II.
Rex

#11 RAKing

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Posted 08 October 2013 - 04:48 PM

I wish the DSC worked with my Gemini-2...

there is a thread about that, the new high resolution Losmandy kits should be ready in a couple weeks, then Rene may activate that function in the Gemini II.
Rex


Sorry, I thought it was active. My fault for mentioning it. :foreheadslap:

Ron

#12 tomcody

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Posted 08 October 2013 - 08:24 PM

No problem,
If I remember its in this mount section and called Losmandy DSC's?
I spoke with Scott and the new encoder kits may be ready in mid October.
Hopefully, then Rene will activate the encoder suppport in Gemini II's.
Rex






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