Help! HEQ5 Goto Grinding Noise!

[samtheeagle]

Although conditions last night were pretty poor in my area, it was clear, so I decided to setup to try out my new guiding configuration. Halfway through the session I decided to slew to a new target, during which a horrific grinding noise came from the mount for a good few seconds This has obviously freaked me out, as my mount is my pride and joy. I've used it a few times since upgrading it from a standard HEQ5 to a Synscan one, and it's worked flawlessly, but chance are it's down to a poor job of fitting the motors on my part.

Will I have done any serious damage? I managed to park the mount afterwards, and that seemed to go ok, so the motors are still working, but I dread to think what I might have done to insides of them... When the mount finished parking I found that the DEC axis was about 10 degrees off where it should have been, so it would appear that's the axis that created the noise of terror.

I shall of course revisit AstroBaby's HEQ5 strip down guide to get my bearings again... But I'm guessing that the likely cause is the fitting of the Synscan upgrade. Anyone have experience of this kind of grating / grinding noise during a slew? Is something too tight and binding, or too loose and slipping? I have stripped the mount down before as per AB's guide, and it's all been regreased and running fine until last night.

Any advice will be very gratefully received!

[Rustysplit]

Could be that you have a tight spot in the gears somewhere causing the motor to stall at that point. Does not cause damage, but sounds awful!!

Have a look at the gear meshing set up again.

Or, check that the power lead has the correct centre pin size. Should be 2.1mm if the same as eq6. My mount came supplied with the wrong lead and showed just these symptoms. Took ages to track the fault down.

Good luck.

[riklaunim]

If it stopped moving and made those noise the there isn't just enough backlash for the axis to move. It can happen if you limit the backlash when the mount is warm, and then put it in the cold - that makes it even smaller and may block the axis from moving (+ make those creepy noises from the motor). It shouldn't damage anything.

[malc-c]

Does sound like a gear mesh, either too tight it caused the motor to stall, or too loose it slipped. One other possible cause could be that the cold caused the worm gear to slip ?

One possibility to overcome the gear mesh is to convert the drive to belt drive http://stargazerslounge.com/diy-astronomer/160466-heq5-experiments-belt-drive.html

[samtheeagle]

Thanks for the suggestions all. So basically I want to be looking at the DEC axis gears. I was pretty cold last night, -3 by the time I packed up, so perhaps it is the fact that it was calibrated in a toasty warm house. Perhaps I shall work in the garage when I start looking at fixing whatever the issue is, so there's less of a temperature differential to when it's being used.

Glad for a bit of reassurance that it shouldn't have done any permanent damage

[riklaunim]

Just check if those gears:

Can easily move. If they lock - the motors will make the noise