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Upgrade to Losmandy High-Torque motors worth it?

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#1 StephenW

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Posted 13 February 2018 - 03:48 PM

Hi,

 

I have a TMB 152 mounted on Parallax HD150 running Gemini 1, running the original (non-Maxon) servo motors.  The motors work just fine and have no issues moving the scope/camera etc around, as long as they are well balanced.  Lately though I have been switching between different configurations (e.g. adding/removing a heavy focal reducer) and if I'm not careful re-balancing, I hit motor lags.

 

I'm wondering if anyone has done an upgrade from the original servo motors to the new "high-torque" motors?  Did you notice a significant change/improvement?

 

And does anyone know what the actual torque specs of the original and new motors are?  I've been unable to find those specs anywhere.  It would be nice to know just how much more "high-torque" the new motors are! (are we talking 10% improvement? 50%?).

 

Thanks in advance for any info you may have!

 

Steve

 

(p.s. Haven't done so yet, but yes I will post on the Gemini/Losmandy Y! groups if I can't figure it out with CNs help :)

 



#2 macdonjh

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Posted 13 February 2018 - 04:06 PM

I have my G11 "overloaded", but well balanced.  To keep things under control I have the slew and go-to speeds down at either 600 or 800.  I don't have stalls.

 

I called or e-mailed Losmandy once, and Scott sent me the output torque of the Maxon motors once.  I don't remember the value now, but I bet Scott does.


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#3 StephenW

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Posted 01 March 2018 - 07:11 PM

Well, I went ahead and did the upgrade.  Just installed the new high-torque motors and there is a major improvement in the amount of imbalance they can handle! 

 

The original servo motors were very sensitive - moving one of my (33lb) counter weights a couple of centimeters either direction on the c/w bar would induce RA motor lags.  With the new motors I can literally move one counterweight all the way out to the end of the bar (about 8 inches from the "balanced" spot) and not cause any motor lags :).

 

So - very happy with the upgrade.  It will make switching gear and keeping the everything loaded to the East a lot easier.

 

Steve


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#4 baron555

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Posted 01 March 2018 - 07:46 PM

Now, make that engine just purr, from the Gemini-2.com site, under FAQ:

 

What is the power requirements for the Gemini-2 and the power connector sizes.
Answer: The Gemini-2 has 2 barrel connector inputs (Gemini-2 Mini only has one) much like what is used on laptop computers.  The outside diameter is 5.5mm and the inside diameter is 2.1mm.  The Gemini-2 is designed to be able to provide a absolute maximum of 2.8 amps to each motor. The Gemini-2 is fused at 5 amps on the inputs.    The Gemini-2 is not designed to function on voltage less than +12 volts and can work all the way up to +18 volts safely.  I recommend at least a +5 amp 12 volt switching power supply. The reason for the 5 amps is that some power supplies will drop the voltage below it's rating when higher amperage is required, like slewing.   This needs to be a good quality power supply, and many of the lower cost units puts out a lot of voltage spikes and are not well regulated.  You have invested $1000.00 in the Gemini-2, so don't skimp on the power supply. I personally use a 16V 7 Amp medical rated power supply.  Sorry they are not made anymore as it was quite reasonable at $80.00 and has performed quite well for both my Gemini-1 unit and now my Gemini-2 unit. The 16 volts seems to be a sweet spot where both the G1 and G2 works well at. A very similar unit by the same company but at 15V at 6.67 amps is here.

 

I use this latter unit and it does just fine.



#5 StephenW

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Posted 01 March 2018 - 07:54 PM

Thanks for the recommendation!

 

I'm using the Powerwerx 30amp supply that outputs 14V to run all my 12V devices.  Seems to be working for now, but if I see I need more juice I do have a separate bench supply that I could run at 16V (or higher) for the mount :)

 

And the new motors do indeed "purr", at least compared to the old ones ;)


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