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Downward Bound
Adrenaline Junkie
Reged: 03/29/06
Posts: 2641
Loc: Seattle
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I’m having issues with my G-11/ Gemini. After initial start-up (cold or warm) I choose a star for as my first alignment star from the menu and select “go to bright star”. Instead of the mount slewing, I get an error message that reads “Motors Stalled!”. I have attempted a number of “fixes” (re-boot, unplug/replug all connections, loosen/tighten clutches, change power supplies….) and consulted the cryptic manual but have not been able to get mount operational. Has anyone solved this issue before or have any suggestions? Sometimes prior to getting through the set-up I also get a “DEC motor lags!” error message before I even get to the “motors stalled!” message. I’m going to try un-install/re-installing the servomotors and check the worms to see if anything is bound up too tightly but I’m about at the end of my (mechanically incompetent) rope. 
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Bill
'flector: R200SS, 22" f/3.6 (on order)
'fractors: PST, AT-66, TV-85, FS-102, NP-127, TMB-152
'bins: 15x63, 10x52, 22x85
410+028B, Sphinx, Telepod, EZ Touch, G-11
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blueman
Vendor Blue Sky Accessories
Reged: 07/20/07
Posts: 1427
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HI Bill,
This sounds like your worm is too tight, that will cause this issue. Or anything else that will not allow the motor to turn easily.
You should check this before you burn a motor out.
Blueman
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14.5" Starmaster with ServoCat and Argo Navis
AT 8" RC
TV NP101 f/5.4 APO Telvue .8 Focal Reducer
WO 80mm f/6 APO Televue .8 focal reducer
SBig ST2000xm with CFW-9 filter wheel
Astrodon Gen2 filters RGBL
Baader HA,O-III, H-Beta, S-II Filters
Losmandy G-11 Gemini Auto-guided
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skybsd
professor emeritus
Reged: 02/01/08
Posts: 598
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Hello,
Here are some things to check off: -
a] At start-up, but without running any alignment attempt, can you move in DEC / RA?
b] Have you checked the balance of your equipment on both axes?
c] How are you powering your equipment? You want to make sure that a clean and stable 13.8v (minimum) is being presented to the mount.
Hope this helps..,
Regards,
skybsd
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Downward Bound
Adrenaline Junkie
Reged: 03/29/06
Posts: 2641
Loc: Seattle
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Quote:
HI Bill,
This sounds like your worm is too tight, that will cause this issue. Or anything else that will not allow the motor to turn easily.
You should check this before you burn a motor out.
Blueman
Yes that’s my plan to do next. I didn’t spend too much time trying to ‘force’ the issue once I got the error – as you say, I didn’t want to burn out the motor(s).
Quote:
Hello,
Here are some things to check off: -
a] At start-up, but without running any alignment attempt, can you move in DEC / RA?
b] Have you checked the balance of your equipment on both axes?
c] How are you powering your equipment? You want to make sure that a clean and stable 13.8v (minimum) is being presented to the mount.
Hope this helps..,
Regards,
skybsd
a) I haven’t but I will give it a try – thanks!
b) Yes, my balance is pretty much spot on so I doubt it’s the culprit, but it’s worth noting.
c) I believe my power supply is fine as it is rated higher (and has powered this mount before) but I’m going to put a meter to it to see – it may have deteriorated with time/usage.
Thanks for the ideas guys…… I’ll keep plugging away….
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Bill
'flector: R200SS, 22" f/3.6 (on order)
'fractors: PST, AT-66, TV-85, FS-102, NP-127, TMB-152
'bins: 15x63, 10x52, 22x85
410+028B, Sphinx, Telepod, EZ Touch, G-11
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blueman
Vendor Blue Sky Accessories
Reged: 07/20/07
Posts: 1427
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If it is only one axis, you might try removing the motor, just two screws, and then run the motor. If it runs OK, then try to turn the worm by grabbing the Oldham coupler and see if it is tight or not. If it is tight then you will need to adjust the worm.
Sometimes this happens when the temperatures suddenly change with the seasons, especially if it was just a little tight.
But, it could be something else, like the bearings on the shaft. But just checking the two things I mentioned should help isolating the source of the problem.
Blueman
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14.5" Starmaster with ServoCat and Argo Navis
AT 8" RC
TV NP101 f/5.4 APO Telvue .8 Focal Reducer
WO 80mm f/6 APO Televue .8 focal reducer
SBig ST2000xm with CFW-9 filter wheel
Astrodon Gen2 filters RGBL
Baader HA,O-III, H-Beta, S-II Filters
Losmandy G-11 Gemini Auto-guided
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Cotts
Just Wondering
Reged: 10/10/05
Posts: 907
Loc: Richmond Hill, Ontario
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quote: c) I believe my power supply is fine as it is rated higher (and has powered this mount before) but I’m going to put a meter to it to see – it may have deteriorated with time/usage.
If your power supply doesn't provide enough current you'll get these messages. I run my G11/Gemini with a power supply that provides 7amps peak and 5 amps continuous. I believe the manual mandates a power supply of this strength.
Dave
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David Cotterell
14th Floor Observatory
Richmond Hill, Ontario
200 mm Intes f/10 Mak-Cass
80mm WO Zenithstar FD
66mm WO ED
Losmandy G-11 mount with Gemini
Ioptron minitower
Canon XSi
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Downward Bound
Adrenaline Junkie
Reged: 03/29/06
Posts: 2641
Loc: Seattle
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Thanks Floyd, I will remove the motors and check.
Dave, the more I think on this the more I think it's the power supply. I'm going to pick up a meter on the way home tonight and get a new power supply if mine is insufficient.
Thanks
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Bill
'flector: R200SS, 22" f/3.6 (on order)
'fractors: PST, AT-66, TV-85, FS-102, NP-127, TMB-152
'bins: 15x63, 10x52, 22x85
410+028B, Sphinx, Telepod, EZ Touch, G-11
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Billydee
super member
Reged: 01/23/08
Posts: 184
Loc: Winter Haven, FL
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If you need to replace the 110V to 13.5 volt PS get the Pyramid 10 A unit (same company that makes the Losmandy 5 amp PS @ $85). You can have your local Ritz Camera shop order the 10 amp unit for just over $55 or the 5 amp unit for $45. The G-11 really runs best at 18 Volts. The better battery PS for the G-11 is Kendrick it has one 12V output and one 18V output (17 amp hrs) for $300 or the best one is one 18V output and three 12V outputs (33 amp hrs) for $400 (plus a special cord for the 18V output just for the Gemini @ about $60 (the cord keeps you from frying your camera or computer).
Luck, Bill
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jrbarnett
Eyepiece Hooligan
Reged: 02/28/06
Posts: 4341
Loc: Petaluma, CA
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It may also be a bad motor or two. One of our club members purchased a Gemini retrofit kit from Losmandy and experienced the same problem/error. Losmandy ended up replacing both motors and verifying that both original motors were defective.
Regards,
Jim
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"I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."
- Sir Issac Newton
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Billydee
super member
Reged: 01/23/08
Posts: 184
Loc: Winter Haven, FL
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Note on the Pyramid PS (10-amp, 13.8 volt). Now it is online only from Ritz and it is $42.89 plus $6.95 = $49.84.
The Kendrick items are in Canadian dollars so they are actually cheaper. They ship from a NY address so no customs duties and shipping is free (big savings at a shipping weight of 39lbs for the large one). You do have to pay your credit card company an exchange surcharge for the Canada to USA currency exchange.
Bill
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revans
Carpal Tunnel
Reged: 09/26/05
Posts: 1514
Loc: Fitchburg, MA
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Is your scope balanced properly on the mount?
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Rick Evans
http://www.freewebs.com/revans_01420/
"The universe is there for us to see, but it cannot be understood without learning its language -- mathematics." Galileo Galilei
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Downward Bound
Adrenaline Junkie
Reged: 03/29/06
Posts: 2641
Loc: Seattle
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Thanks Bill for the Pyramid recommendations. I'll likely pick one of these up for use when viewing at home. However, I have a few dark sites I like to visit that are off the grid and as such have no 110 AC. I haven't been able to find any options for 18V battery systems with the amp/hrs required. I suppose an option could be to set up a series of 6V or 12+6V batteries. Has anyone come up with a good battery solution for 13.5-8 volts?
Jim - interesting point about the bad motors. I'll try the Pyramid 110-to-DC power supply and if that doesn't isolate the problem then I'll contact Losemandy about replacing the motors.
Yes, I always make sure that the scope is carefully balanced.
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Bill
'flector: R200SS, 22" f/3.6 (on order)
'fractors: PST, AT-66, TV-85, FS-102, NP-127, TMB-152
'bins: 15x63, 10x52, 22x85
410+028B, Sphinx, Telepod, EZ Touch, G-11
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neptun2
sage
Reged: 03/04/07
Posts: 277
Loc: Bulgaria
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You can also get good 12V power tank and use laptop car adapter to get 18V.
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Skywatcher Explorer 200P 8" f5 newtonian reflector
HEQ5 Pro Synscan Equatorial mount
Nikon Action 12x50 , Nikon D5000
Nagler type 6 11mm , Pentax XW 7mm , Televue 2x barlow 1.25"
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revans
Carpal Tunnel
Reged: 09/26/05
Posts: 1514
Loc: Fitchburg, MA
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I suspect the following is not the cause of your problem, but when I first got my G11 mount it acted in a similar way because I had failed to specify that the mount was in fact a G11 and the Gemini software defaulted to a Titan mount type. This caused all sorts of weird problems until I discovered this and set it straight. But I was a brand new owner of the mount at the time and didn't know the least thing about how to use it at the time. I just thought it was worth mentioning... although again, I'm sure this is a mistake that you most likely would not make...
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Rick Evans
http://www.freewebs.com/revans_01420/
"The universe is there for us to see, but it cannot be understood without learning its language -- mathematics." Galileo Galilei
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Downward Bound
Adrenaline Junkie
Reged: 03/29/06
Posts: 2641
Loc: Seattle
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Thanks Rick, but I do have the Gemini correctly set to "G-11".
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Bill
'flector: R200SS, 22" f/3.6 (on order)
'fractors: PST, AT-66, TV-85, FS-102, NP-127, TMB-152
'bins: 15x63, 10x52, 22x85
410+028B, Sphinx, Telepod, EZ Touch, G-11
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Downward Bound
Adrenaline Junkie
Reged: 03/29/06
Posts: 2641
Loc: Seattle
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I've ordered the Pyramid PS-15KX 13.8V 12A power supply to see if a change of power will fix the problem or at least rule out a possibility. I'm also going to check the motors to see if they are the cause. I'll post what I learn .........
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Bill
'flector: R200SS, 22" f/3.6 (on order)
'fractors: PST, AT-66, TV-85, FS-102, NP-127, TMB-152
'bins: 15x63, 10x52, 22x85
410+028B, Sphinx, Telepod, EZ Touch, G-11
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HunterofPhotons
sage
Reged: 04/26/08
Posts: 266
Loc: Rhode Island, USA
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Check the worm!
Not only is it the most common cause for a motor stall, but it needs to be eliminated before you start ramping up the power.
It's like when you've started stripping the threads on a screw, pushing harder doesn't help the problem, it just strips more threads. <g>
Do the procedure Blueman suggested with the Oldham coupler.
It's easy enought to do, and needs to be done routinely anyway.
dan
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