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G11 with Gemini II acting weird

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#1 Hilmi

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Posted 11 December 2012 - 04:17 PM

OK, So I have not used my mount for a week and last I used it, it was perfectly fine. I traveled for a week and when I came back I hooked up my adapter to for the optec lepus reducer which pushed my camera further out. So I re-balanced the mount as per my usual procedure starting with Dec balance then RA.

I powered the gemini II and durring my first alignment slew, the RA stalls. Usually when it stalls, it will respond after for example loosening the worm gear meshing. This wasnt the case, the motor was super hot. So I disconnected everything and waitted for the motor to cool.

I tried reversing the RA and Dec cable and couldnt see a problem with the cable, so i reballance. Same issue.

After a few restarts, It agree's to slew, but it keeps on stalling on both Axis, as if it is not getting enough power. It is hooked up to a 16.5 V laptop power supply and I validated this through the gemini web interface. Any idea what's wrong?

#2 Hilmi

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Posted 11 December 2012 - 11:28 PM

Bump! Need help, I'm going to a Star party tomorrow. Also posting on Yahoo groups now

#3 blueman

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Posted 12 December 2012 - 01:16 AM

Check the power supply for correct voltage.
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#4 Hilmi

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Posted 12 December 2012 - 02:09 AM

Getting 16.5 V according to the Gemini II web interface.

#5 mega256

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Posted 12 December 2012 - 03:01 AM

Wonder what the power looks like under a load?..
You might look at the voltage when doing a goto, and you may even hold the scope while slewing....There may be a poor conection to the power supply,and might show up only under load..Now that its doing it in both motors the most common thing would be power or connections to power.A tarnished conector might do this.

#6 Hilmi

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Posted 12 December 2012 - 04:56 AM

Gonna shop for CRC conact cleaner today. Hope it works

#7 Bowmoreman

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Posted 12 December 2012 - 06:22 AM

I occasionally had power related issues with my Gemini I until I just broke down and bought a dedicated 80 Amp marine battery for it... Nary a problem in the year since... Ac adapters are prone to flakiness in my experience... Volts might be ok, but you might get amp issues, or vice versa... Good luck

#8 Hilmi

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Posted 12 December 2012 - 06:40 AM

Dave,

I actually have a brand new car battery that I had never used before to power anything, I had it on my battery tender to keep it charged. So I hooked it up to trouble shoot last night and to my disappointing it turned out to be giving out 11.2 V which is way too low to power the mount.

#9 Hilmi

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Posted 12 December 2012 - 12:10 PM

Slews now working but movements are jerky and my tracking is horrible. Im starting to really dislike this mount

#10 gdd

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Posted 12 December 2012 - 12:44 PM

I powered the gemini II and durring my first alignment slew, the RA stalls. Usually when it stalls, it will respond after for example loosening the worm gear meshing. This wasnt the case, the motor was super hot. So I disconnected everything and waitted for the motor to cool.



Motors damaged?

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#11 Startraffic

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Posted 12 December 2012 - 01:04 PM

Hilmi,
Answered on Yahoo group too but....
I'd check for either grit in drive train in you're in a high dust area IIRC. If that's clean then I'd look at the Worm mesh. Too tight will cause binding, motor overheating, burnouts, or if just a little too snug then Lagging errors, poor tracking , etc.

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#12 Hilmi

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Posted 12 December 2012 - 02:38 PM

I actually took your suggestion and took it a step further, I went and polished the worm gear by hand using some mild non abrasive polish, its now far smoother, The slews are quieter, but my tracking is not as good as before this saga happened. I suspect you are right and my motor is on its way to kicking the bucket. what unfortunate timing. Just when I got my focal reducer going :(

#13 Startraffic

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Posted 13 December 2012 - 07:14 PM

Hilmi,
You haven't had it that long & you've had "issues" with it all along, Why not email Scott or Russell & see if they'll send you a new worm? Can't hurt & they just might. If they say no then a new Brass high precision worm is $65 USD + shipping which would still probably be under $100 USD. Still worth doing.

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#14 Hilmi

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Posted 14 December 2012 - 07:06 AM

Motor kicked the bucket as confirmed by the hours wasted setting up under perfect skies and finding the motor dead :(

#15 Startraffic

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Posted 14 December 2012 - 12:59 PM

Hilmi,
That would be Murphy paying you a visit. He happens to have a permanent place in my back pocket, right beside my wallet.

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#16 mega256

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Posted 14 December 2012 - 03:04 PM

I bought a new motor (hd) ,used the old for a spare..The new motor is very much stronger!So much that I bought a ($35 spare gear box,just incase)I can get a much better fit on my RA worm...works great.And runs cool compared to the old one moving mt C14..The new losmandy motors seam much better than even the maxum..Wasnt cheap,but solved my problem.I called and they had it to me in 2 days.(Florida)good luck..

#17 Hilmi

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Posted 14 December 2012 - 03:06 PM

Murphy is a secret agent of whoever is managing the US economy. It's always some gadget that dies on me and the parts need to be shipped in from the US. He probably also owns shares with Fedex, UPS and USPS.

Anyway, jokes aside. When I took the mount apart to clean it, I could not find any grit in the gears, but I did find that one of the two cubes that hold the worm gear in the OPWB was for some reason not seated properly. I find this odd, I checked it last time after assembly, I could have missed it, but I recall being rather thorough. So I guess the worm was binding and that overloaded the motor, which is why my second motor also died out when I swapped out the motors.

Anyway, I took the chance today to use a polishing wheel on my Dremel tool and I polished both the worms as per some instructions that I found online which indicated that this same process gave very good results for that user. Thing is, he used a very specific type of polish that's not available in our market. I used some liquid chrome polish, which isn't all that abrasive. Running my finger over the gears, they feel smoother, even that damaged one that I had put on my DEC axis, the scratches on it just feel a bit rounded. Now I need to budget for new motors before I can do any imaging. This time before I put on the motors I am pulling the entire mount apart for a thorough clean up.

Edit: $225 a pop without shipping! I need two of them too! I need to sell something so that I can fund these motors.

#18 terry59

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Posted 14 December 2012 - 05:14 PM

I need to sell something so that I can fund these motors.


Children? Life insurance policy? :tonofbricks:

#19 Hilmi

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Posted 14 December 2012 - 10:01 PM

Unfortunatly. I have only 1 child. The wife would notice.

#20 Joe C

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Posted 14 December 2012 - 10:23 PM

Then the wife it is :roflmao:

#21 Hilmi

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Posted 14 December 2012 - 11:47 PM

I'm saving that for when I decide to buy an AP1600 and the kid for when I want to put a 6" AP refractor on it.

But with all seriousness, I'm still confused as to what caused the motor burn out. I'm not convinced it is to do with the with the cubes holding the worm blocks as I am very sure I had them installed properly after I last took them off. I even remember checking for gaps to confirm I had proper seating. After this, I used the mount for at least a week with smooth performance, so that can't be it. When I balance the mount, it does not move all that freely, could it be that I thought it was balanced but it wasn't?

I think my warranty is out, but I will attempt to request a goodwill replacement of the motors, because as mentioned earlier my mount never really worked up to expectations.

#22 Hilmi

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Posted 15 December 2012 - 08:48 AM

Scott is a great guy, I told him my motors where burnt out and he offered to send me new ones if I sent him the old ones back.

#23 terry59

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Posted 15 December 2012 - 11:09 AM

You can't beat that

#24 mega256

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Posted 15 December 2012 - 02:52 PM

still BUILT in the USA..........with USA service.

#25 Hilmi

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Posted 12 January 2013 - 07:52 AM

Just got my replacement motors from Scott. Communication was poor throughout the process as I was left in the dark for almost a month with no idea what's going on, but... I am still very very very happy. I just got a package in the post today with the brand new high torque motors. That's actually a paid for upgrade for the mount and I got it as a warranty replacement for my old motors. I'm a happy man :) Going upstairs to install these new babies right now!






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