Alt motor only moves at max speed

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Sky17
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Alt motor only moves at max speed

#1

Post by Sky17 »


The alt motor drive on my Meade DS-2130 operates only at max speed. Selecting any speed from the Autostar controller results in max speed movement. The horizontal drive works properly at all speeds. I’ve tried new batteries, reset, motor calibration, motor training, and a different Autostar controller but none of those have solved the problem. I’ve inspected the electrical socket the Autostar plugs into - it looked pretty clean, but I lightly cleaned it and sprayed some contact cleaners on it; that didn’t help either. Any thoughts on what’s causing this problem and how to fix it? Thanks!
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Piet Le Roux South Africa
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Re: Alt motor only moves at max speed

#2

Post by Piet Le Roux »


Good day,
It appears that the encoder coupled to the alt drive motor is faulty or not plugged in properly and is not supplying the right feedback to the alt drive board, so it thinks that the motor is turning very slow and is supplying full drive to the motor. What controller are you using with the DS-2130? Because a Autostar 497 should report a motor fault. You would have to open the alt drive and board so we could see what they look like and direct you to the encoder.
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: Alt motor only moves at max speed

#3

Post by Sky17 »


I’m using the 494 autostar controller as well as a 497. I do occasionally get a motor fault when making the scope move a long distance at high speed. But most of the time no fault is displayed. The motor calibration and training occur with no error message. Any tips on how to open it up to see the alt board and motor?
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Re: Alt motor only moves at max speed

#4

Post by Piet Le Roux »


Sky17 wrote: Fri Jun 19, 2020 9:56 pm I’m using the 494 autostar controller as well as a 497. I do occasionally get a motor fault when making the scope move a long distance at high speed. But most of the time no fault is displayed. The motor calibration and training occur with no error message. Any tips on how to open it up to see the alt board and motor?
No, I have no knowledge to disassemble a DS-2130 but I think I have seen some information on the Cloudy Nights forum, so do a search on their Meade forum and see what you can get. How did you manage to do training of the Alt drive? did it still move at full speed? I usually slow down to a "2" speed when It gets close to the target when doing training.

I found this : http://www.data-plumber.com/dsmotors.htm

PS in this photo you see the motor attached to a wheel with gaps in it, a led shines through the gaps to a optocoupler , that's your encoder.
dsmotor07.jpg
dsmotor07.jpg (21.24 KiB) Viewed 11424 times
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: Alt motor only moves at max speed

#5

Post by Sky17 »


I opened it up - that went smoothly. Here are three photos. The gears and optical chopper disk all spin - but still all at max speed of course. What do you think?
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Piet Le Roux South Africa
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Re: Alt motor only moves at max speed

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Post by Piet Le Roux »


First give me some feedback on its behaviour when you did training of the Alt drive, did it run at full speed then ?
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: Alt motor only moves at max speed

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Post by Sky17 »


Yes, the alt drive runs at full speed when training regardless of the speed setting I select with the controller. I can’t do an accurate training at that speed, but no faults are displayed.
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Re: Alt motor only moves at max speed

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Post by Piet Le Roux »


I would suggest that you check that there is no dirt in the encoder between the led and optocoupler. If that does not solve your problem the only person that I know that could help you is Andrew Johansen, he is active on the Cloudy Nights Meade forum and posts as OzAndrewJ. Place a post there or PM him.
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: Alt motor only moves at max speed

#9

Post by Sky17 »


Will do. No signs of dirt in the encoder, but it’s beginning to look like a voltage issue. I measured 5v at the detector of the encoder, but no voltage at the ir emitter. I need to confirm that in the coming days and, if true, I can work back from there. Thanks again for your help.
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Re: Alt motor only moves at max speed

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Post by Sky17 »


Problem solved! There seemed to be two issues. The first one was that the IR-LED and detector had moved out of alignment. I reseated them firmly in their sockets and secured with a dab of silicone caulking. Then a second problem was found. The drive motor would sometimes rock/rotate/move a bit in its housing. Only a few degrees (guessing about 5 degrees). But when the motor is in that shifted position the motor would revert to only running on max speed. I couldn’t see any reason for this, but it was highly repeatable and I could make happen just by slightly moving the motor. I couldn’t see anything electrical like a short. My best guess is that maybe it somehow was affecting the IR-LED - Detector alignment - although I couldn’t see how. A dab of hot glue secured the motor in a “good” position. Anyway, the Alt drive speed problem is solved. Although now its gearlash seems excessive (much longer delay than AZ drive) - I’m working that issue now - it may be a new thread... Thanks again.
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Re: Alt motor only moves at max speed

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Post by Piet Le Roux »


Great news! So it was a case of the controller not getting the right feedback from the motor movement.
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: Alt motor only moves at max speed

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Post by Piet Le Roux »


I don't see any worm gear on the photos you took but that is where the most gear lash develops. The worm gear configuration in my LX90 have partially solved the problem by allowing the drive to pivot and then spring loading it so the tension between the main gear and worm gear is always the same but in other systems the angel and tension is adjustable. This is not easy to adjust because too little means a lot of play and to much can lead to excessive drag and even damage to the gears and motor. When you say "delay" is that the time it takes the Dec counter to change value or for the OTA to start moving? Because the delay in the counter reading is dependable on your training value of that drive.
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: Alt motor only moves at max speed

#13

Post by Sky17 »


The worm gear and the very large gear it turns both respond quickly to reverses of direction. It turns out it was a clutch issue (well maybe a user error issue...). I cleaned it up a bit, but mainly I think I just wasn’t tightening it enough. There is some gap between the sides of the clutch dog “legs” and the slots they fit into, so that still contributes to the remaining gearlash, but it now seems to be “normal” and about the same as the AZ drive system. So it’s all good to go now! Except for the cloudy, rainy weather forecast for the week... Thanks again.
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Re: Alt motor only moves at max speed

#14

Post by Piet Le Roux »


If you load the 43GI firmware patch for your 497 Autostar controller from, https://www.stargps.ca/downloads.htm, your can read your training values from the controller after you have done drive training. The default value is "100", below that means you have very little "gearlash" above that, especially above "200" is not good. I use this value to determine if I need to adjust the drive or not. The way it works is when you do drive training the Autostar measure the average rotations needed by the motor, after a direction change, before movement takes place. These rotations are then disregarded by the Az or Dec counter every time direction is changed to maintain accuracy.
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: Alt motor only moves at max speed

#15

Post by Sky17 »


Thanks for the suggestion for the 43GI firmware patch. I updated my controller and redid Calibration and Drive Training. Here is what I have for gearlash: AZ is about 1250. ALT is about 4000. So clearly not good by your standards. But, it’s been working fine for my simple viewing of Jupiter and Saturn. Is it simply that the drives in this scope (DS-2130) are not designed to have lower gearlash? I know the Alt clutch has what appears to be intentional lag with the clutch dog issue I mentioned earlier. In any case, I’m happy that both drives are at least operational enough to make my viewing enjoyable again.
Thanks again.
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