heq5 judders every few seconds while tracking

[bilkusg]

I have an HEQ5 which often, but not always, judders slighly every few seconds while tracking an object. The mount is well balanced, and behaves fine when using the motor to seek or otherwise manually. 

Every time the judder happens there's a slight banging noise from inside the  mount. I've taken off the gear train cover and can't feel or see any lack of smoothness in the gears . 

If I disconnect the RA so the mount runs free in RA, but leave tracking on, the noise stops.

Any ideas - is this a known issue with a fix which doesn't involve sending the mount away for repair?

Thanks

Edited August 1, 2018 by bilkusg

[Thalestris24]

Hi

What is the history of this problem? Presumably it hasn't always been present - had you adjusted anything prior to the judder showing up? What kit do you have loaded?
It may just need some adjustment such as the worm gear - see Astrobaby's wonderful maintenance guide:
http://www.astro-baby.com/heq5-rebuild/heq5-we1.htm

Louise

[bilkusg]

Thanks. I am familiar with the maintenance guide, and have already tried to adjust the worm gear before this post ( but after the original symptom )  but it makes no difference ( unless i've done it wrong ). This post is my final attempt to work out what's happening before I bite the bullet and try the full strip down....

I noticed it first shortly after I got the mount about two years ago, but only during one particular session. When I investigated further at the time, I couldn't recreate the problem at all, so I put it down to possibly my battery needing charging at the time and forgot about it.

Since then, the mount hasn't been used much until a few weeks ago when I took it down to southern France on holiday, and now it's happening a lot, but more often when the telescope is to the east and the weight to the west. I've tried balancing the thing very carefully, and it makes no difference. In fact, even when it's out of balance deliberately, there's no difference which way the balance is wrong. 

I've also updated the SynScan firmware to the latest version just in case, but that's also not helped.

My options at this point seem to be

1. Try adjusting the RA worm again

2. Try the full strip-down

3. Send it off for repair.

But i'm kind of hoping someone will recognise the presise symptom......

[gajjer]

Hi.

My first question would be: does it track correctly? I wonder if the 'banging noise' is the stepper missing a step which might indicate binding. Perhaps meshing is too tight.

Just a thought

gaj

 

[Owmuchonomy]

Does your LED flash at all during operation. Before you strip down and service the worm float I recommend you exclude a power supply issue. Make sure you have sufficient power to operate a fully loaded mount. For your mount you need over 2 amps, preferably a 4 amp supply at a nominal 12 volts. Can you use a regulated mains supply rather than the battery you mention?

[bilkusg]

Thanks all for your suggestions. After playing around this morning with the moon, I think I've finally discovered the problem, which is, in retrospect, trivial, but may be of use to others.

The cap for the polar scope was on tight, and the RA setting circle appears not to be well seated, so when I had the setting circle tighened against the RA axis it was causing just enough friction to cause juddering when tracking slowly, but not so much that things didn't appear smooth at any faster speed. The RA circle appears to be slightly out of true, which is why it was worse in some orientations than others, but not consistent.

When I loosened off the RA circle, the problem disappeared, although it means I can't use the RA circle for manual setting, but that's a relatively minor problem! 

Hopefully the fix will be confirmed when I give the scope a good test tonight. Otherwise, I'll be back!

Phew....

Edited August 2, 2018 by bilkusg

[Thalestris24]

Yes, the setting circle is useless - time they stopped even including it! Best advice is to leave it loose permanently. Adjusting the worm gear is very tricky - just tiny movements and can take a number of iterations to get just right. Hopefully, you won't have any further problems now.

Louise

[bilkusg]

Just wanted to close this off by confirming that the mount is now behaving impeccably with the RA setting circle loose. Hope that this thread may save someone else a bit of time or expense in the future.

Thanks again for the suggestions.

[Stub Mandrel]

On 02/08/2018 at 08:01, gajjer said:

Hi.

My first question would be: does it track correctly? I wonder if the 'banging noise' is the stepper missing a step which might indicate binding. Perhaps meshing is too tight.

Just a thought

gaj

 

That was my thought as well, or out of balance in DEC. Also, I found that perfect mesh with an unloaded mount became binding with the weight of a scope on eth mount.

Edited August 4, 2018 by Stub Mandrel

[Richy P]

Sorry to resurrect this tbread but im currently experiencing the exact same issue! I bought the mount from new and every 5 seconds or so you can hear a very definite 'clunk' where it sounds like the ra tracking is being restricted somewhat then suddenly judders back to tracking correctly. Its obviously ruining any long exposures im taking. 

I'm a bit new to all this and wondered what you menat about loosening the setting circle? Is it tne green band just above the polar scope? Do i need to remove the holding screw so that it freely rotates?

 

Many thanks, 

 

Rich