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Trouble shooting right ascension motor problems

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#1 Michael Lomb

Michael Lomb

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Posted 17 November 2012 - 08:59 PM

I added this post as a new thread. It started as feedback to a now deleted post, so it became an orphaned reply. 

When I got my Questar back from servicing a new southern hemisphere RA motor and right ascension dial was installed. The motor runs off the mains, not the power guide 2 that runs off a 9 volt battery. When observing Jupiter I noticed that the planet would still drift out of view. It seemed like the new motor was not working. 

To check I had the Questar sitting on a table with the legs inserted, and watched to see if the telescope tube and fork rotated on the base over the course if a few hours. It did not. Just to be clear here, the right ascension dial rotates with the telescope tube so the reading on the dial does not change when the fork rotates on the base. In my case nothing moved. 

It was a simple matter to remove the bottom plate, as swapping out the motor is something anyone can do. I unscrewed the aluminum mounting screws that held the motor in place and removed it. It is a spur gear arrangement. I plugged the motor in to check if the gear was moving. It was. I re inserted the motor. You need to rock it a bit to make sure the gears mesh correctly, and the mounting screw holes line up. Put the screws in again, not tight, they are only aluminum. The fork now rotated around the base as it should when plugged in. The motor is very quiet. You need good hearing and have to press your ear to the base to detect any sound at all. 

In my case the gears must have jammed in transport. These motors are just too simple to fail and last almost forever, which is why I did not go for an electronic power-guide.  If anything went wrong with the power-guide telescope internals, it would be very expensive to ship the telescope back overseas. I have a wall socket close by so a cord is not a hassle. The Questar controls are so smooth manually turning the right ascension drive is a workable field option should the need ever arise. It is good to run the motor from time to time, as the brushes can get stuck. Company 7 had one running continuously for years in their show room

#2 Steve_M_M



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Posted 18 November 2012 - 01:42 AM


Thanks for the reply on my original thread. I deleted the post as I was getting many more replies over on the Yahoo Questar group. The information posted under your thread here is good information and I appreciate you re-posting it.


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