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neq6 got stuck while slewing is there damage????

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#1 cguvn

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Posted 17 June 2013 - 06:13 AM

hello on my second alignment goto the guider wire got stuck in the azimuth knob and stalled the mount traveling at max speed in R.A.

It made a terrible noise while I was struggling to free it.

I then sent it to park position and it was quite offset in R.A. so I know something slipped.

after restarting, the alignement routine went flawlessly. the problem started when I started guiding.

the blue line started quite well for a minute or two and then going down and down and down. And no matter what I tried it was always the same.

I'm afraid something broke or got misaligned inside. shoud I just follow astrobaby's guide and dissassemble the R.A. axis to see if everything is in place? could I make thing worse?

what do you think?

thank you I will post the PHD graph when I get an unlocked internet.

#2 rmollise

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Posted 17 June 2013 - 08:26 AM

Before you tear into the mount, make sure it's not you. Double check everything. Including polar alignment. If you are using EQMOD, realign with all new sync points, do new alignment points, etc. I would expect it not to have hit Home if the clutches slipped. If this ever happens again, hit the big switch, power it off immediately.

#3 Madratter

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Posted 17 June 2013 - 10:10 AM

Stalling a stepper motor will probably not damage the motor itself but can sometimes damage what is driving it because of voltage spikes. I don't know how well the NEQ6 is protected.

At any rate, Uncle Rod's advice is spot on.

#4 DuncanM

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Posted 17 June 2013 - 03:48 PM

I've stalled my EQ-6 many times without damage. Stepper motors are pretty tough and hard to burn out, however the same cannot be said for servo motors, but you should be fine.

Have you ever guided before? Sounds like a polar alignment or guider controller issue.

#5 cguvn

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Posted 17 June 2013 - 04:41 PM

after the event I made sure the alignment was still good and in fact it was my best to date.

it was not my first guiding. in fact the night before was very good with rms around .11 I think.

is there a way to check PE without actualy imaging something. weather is horrible. I don't have EQMOD only the remote and firmware 3.28 (the beta)

Duncan when you say you got it stuck a couple of times. was it while tracking or slewing full speed?

thanks for the help

#6 DuncanM

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Posted 17 June 2013 - 05:37 PM

after the event I made sure the alignment was still good and in fact it was my best to date.

it was not my first guiding. in fact the night before was very good with rms around .11 I think.

is there a way to check PE without actualy imaging something. weather is horrible. I don't have EQMOD only the remote and firmware 3.28 (the beta)

Duncan when you say you got it stuck a couple of times. was it while tracking or slewing full speed?

thanks for the help


I got it stuck both during high speed slewing and during tracking . When slewing the scope made quite a noise when it jammed but this is just the stepper motors making a racket when they stall at high speed.

Microstepped stepper motors, even big ones as on the Eq-6 have very low torque, because they have very low numerical gear ratios and they will stall quite easily, typically before any mechanical damage can be done. The motors themselves are just big lumps of steel with wire windings and are nearly indestructable, but the spur gears could potentially be damaged, but this is unlikely.

If you are concerned about damage, just pull the motor cover plate off, and pull out the motors (four screws IIRC) so that you can feel the tips of the worm spur gear and visually inspect the motor spur gears. Take a photo before you remove the motors so that you know how it goes back together.

#7 cguvn

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Posted 17 June 2013 - 08:00 PM

ok will do that they are below the electronic panel i beleive and it is much easier job than opening the R.A. gear and worm so much lower risk. I there is no damage on that wheel, I can expect everything else to be safe right (from now on i will put the clutch less tight that's for sure)

#8 EFT

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Posted 18 June 2013 - 09:55 AM

I have yet to see anyone manage to actually do physical damage to one of these mounts with a collision or similar incident. I would not bother with pulling the motors at this point since it is very unlikely any damage has been done to the spur or transfer gears. These gears are so coarse that you simply cannot jump or break teeth on them.

The guider cabling, mount electronics or firmware are the more likely source of damage. Even then, a brief instance of jamming the axis is very unlikely to do damage to the mount electronics. The fact that the mount is operating makes it unlikely that there is damage to the motor board. That is usually an all-or-nothing problem with these mounts. If the motor board is damaged, the mount simply won't work. You probably need to look at your guider cabling and the plugs. Then start looking at the guider set up to see if anything got knocked loose.

#9 cguvn

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Posted 19 June 2013 - 10:03 AM

thank you eft. i tough too that the guiding wire could have been damaged. but it seems to calibrate normally which make me thinks the cable is ok.. I don't think I can use a phone wire can anyone confirm?

#10 rmollise

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Posted 19 June 2013 - 12:51 PM

Check the ST-4 cable with a multimeter...don't fool around with some phone cord.

#11 cguvn

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Posted 19 June 2013 - 01:23 PM

yeah, match the color and look for 0 resistance on each color i guess

#12 cguvn

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Posted 27 June 2013 - 08:25 AM

okay got to test some things. wire was ok, no resisance on every wire but the first wich is normal.

I will join graphs from pecprep and you tell me what you see because either something needs tuning or it is my PHD setting that are wrong.

this is the ''before'' with guiding
Posted Image Posted Image

so a good peak at 10.2 seconds wich is gear mesh period

now guided after the impact (still a 10.2 peak)
Posted ImagePosted Image

and unguided after the damage. almost nothing a 10.2
Posted ImagePosted Image

Soo.. what do you think. is there something to gain by opening it for the gear mesh or my problem is with PHD settings that are too aggresive?

thanks for the help. at least with the weather in eastern canada i'm not loosing any imaging time :S






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