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Atlas EQ-G Slewing Problem

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#1 Jay Park

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Posted 07 April 2009 - 11:15 PM

Today, I put my Atlas EQ-G Goto System out of my Pelican box and tested it to check if my equatorial mount was working in normal condition. (It is a shame to say this, but I did not get my Atlas EQ-G Goto mount out of my box for the last two and a half years because of my busy works.)

I performed the 3-star-alignment just for testing and found my mount DID NOT MOVE! I was frustrated and was in despair for minutes. I turned on and off the mount several times, and all of a sudden, the equatorial mount began slewing! I was about to be happy about this, however I instantly could see my mount began generating lot of grinding noise - the grinding noise which has been frequently noted in this forum. Unlike the usual grinding noise which is noticed at the beginning and ending of slewing under the mount's normal operation, the grinding noise of my mount this time had been with the mount's slewing all along. I even could witnessed that characters shown on the two-line display of my SkyScan GoTo controller were blinking fast while the mount was slewing. (The version of my SkyScan is 3.01.)

The grinding noise kept me crazy, however what made me almost insane was that the slewing of my mount about the RA axis suddenly stopped while I was doing two- or three- star alignments. (When slewing about RA axis stopped, there was zero's displayed on the first half of GoTo controller's display screen.) Even after slewing about RA-axis topped, slewing about DEC-axis was still going on with changed numbers on the second half of GoTo controller's display screen. Once slewing about RA-axis stopped, there was no slewing any longer about RA-axis. (For example, when RA-axis slewing stopped when the mount tried to locate the first star in the 3-star alignment, there was no RA-axis slewing any more for second and third stars. I could still see the mount slew about DEC-axis even after there was no slewing about RA-axis.)

When a cycle for 2- or 3-star alignment, the display screen of my SkyScan said "Alignment failure."

I am very frustrated right now. It looks like my Atlas GoTo mount has a serious problems, and needs significant maintenance. (I have no idea how much it would cost for repair.) I might need to consider selling all my GoTo system (after repairing of the mount) and going for a Dob. It seems the situation of my current job would not allow me to go for a night's observation. (Yes, you can say the way I count my calendar is Monday-Tues-Wed-Thurs-Fri-Fri-Fri; no Saturday or Sunday.) This idea just came up from an assumption that a Dob will not request major maintenance jobs compared to GoTo Equatorial mount.

Any comment is welcomed! Please advise a newbie like me, what would be the best move that I can take now. Thank you so much for your replies.

Dark and Clear Skies to all,

#2 WarrenS

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Posted 08 April 2009 - 06:09 AM

Welcome to Cloudy Nights Jay. One thing I might suggest is to try downloading from the Orion website the latest version of Synscan. Quite often these sorts of slewing issues seem to be hand controller/software related. One thing I've noticed is that I get alignment failure if I'm too quick to try to center the target star before hearing the "beep" during the alignment GoTo.

#3 Charlie Hein

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Posted 08 April 2009 - 06:28 AM

The grinding noises are from the motor(s) binding up. This could be because the mesh of the motor to the worm gear is too tight, and then again it could be because the worm gear to worm wheel mesh is too tight.

Have you attempted to adjust either of these in the past?

I would remove the RA motor and check the worm to wheel mesh by trying to turn the mount in RA with your finger pushing the gear that the motor was trying to turn. It should turn pretty easily. If it does then re-install the motor using just enough pressure to mate the gears and all should be well.

Note: when you remove the two screws holding the motor take care not to drop the washers into the mechanicals of the mount - otherwise this is a fairly straightforward job.

#4 Strgazr27

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Posted 08 April 2009 - 06:47 AM

You can unscrew the chrome plated screw on the side and with a flashlight, visually check the mesh between the motor spur and worm spur. I use a single strip of paper inserted between the 2 gears. Press them together, tighten the motor mounting screw and using the NC, spin the paper out of the way. This is a good spacing for the gears.

#5 rmollise

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Posted 08 April 2009 - 07:04 AM

Post deleted by rmollise

#6 rmollise

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Posted 08 April 2009 - 07:07 AM

The grinding noises are from the motor(s) binding up.


Or it could be a power problem. I'd check the battery/powersupply and cord before doin' nuttin' else, especially before diggin' into the mount and messin' with the gears(!). One reason to suspect the power cord is because at the time he bought the mount Orion was supplying power cords with the wrong connector on the scope end. Turn it on? Nuttin. Turn it off and on again, powers up. Next time? Nuttin'. Low/poor quality power can make this or any other mount make weird, _frightenin'_ sounds, too. :lol:

The odd behavior of the HC is another clue to the problem being "power" related.

#7 Jay Park

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Posted 08 April 2009 - 06:44 PM

Thank you all for helping me to solve the issue!

The problem was with me. Instead of using the AC power supply, I found myself hooking it to the power pack which originally is for cooling down the primary mirror of my Newtonian OTA. This power pack had 8 D-type batteries installed; the voltage was right at 12V, however 8 DC connected batteries were far below the 2 amperes of current, which is the minimum amount of current for normal operation of my Atlas EQ-G GoTo mount. By switching to the AC power supply, all the grinding noise was gone (!!!) along with that blinking problem with display screen of my SkyScan HC!!! Every issue mentioned in the first message of mine is now gone!!! No problem has been found also with the 3-star alignment!

Here, I can see my mistake using another power sources, at the same time however, I learned great thing how my mount would behave when it is not supplied by enough power. In the EQ6 group in Yahoo, I found a document about the step-by-step check list for my Atlas. The first thing on the check list asks its reader if he/she is using the right power supply for the mount! In any event, it turned out the issue that I've had since yesterday came from my stupidity, however I learned great lesson from it also -- Go back to the very basic -- Do not forget having my mount get fed with right electricity.

I personally thank "rmollise" for his kindness leaving the comment.

Hope you all have dark and clear skies,

~Jay

#8 Jeffrey Sugden

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Posted 08 April 2009 - 07:09 PM

You can unscrew the chrome plated screw on the side and with a flashlight, visually check the mesh between the motor spur and worm spur. I use a single strip of paper inserted between the 2 gears. Press them together, tighten the motor mounting screw and using the NC, spin the paper out of the way. This is a good spacing for the gears.


Bobby, you're a lifesaver! My dec axis was stalling on my consistently and I backed of the mesh of the transfer gears a bit and now I can use the goto! Thanks!!!

#9 Strgazr27

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Posted 08 April 2009 - 07:42 PM

Jeff,

Glad I could help. It's a fine line between too tight and too loose. The paper trick works really well. You can play around with it a little more if you want. On mine, the copy paper was a little too much and resulted in a bit of backlash when changing directions or guiding. I than tried a single layer of paper like is used to roll your own cigarettes and it turned out to be perfect.

If you ever have any other issues drop me a PM.

CS's

#10 Jeffrey Sugden

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Posted 09 April 2009 - 06:37 PM

I still have just a bit of stalling. It happens during meridian flip. It's just a small inconvenience. I just do a 1 star align after the flip and then a goto to my target.






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