HEQ5 Shake down advice

[samtheeagle]

So, I've picked myself up a second hand HEQ5 mount for what I hope is a very reasonable price... But given the reasonable price there's the inevitable worry that it's too good to be true. So I was hoping that people out there with this mount might offer me some advice on what things I should be looking for in terms of potential issues.

My initial once over found that the hand controller was being a bit funky with the RA axis, but that appears to have been sorted quite nicely but securing a bad connection to the main circuit board.

Cosmetically it has a few marks, but on the whole it's not in bad nick. The biggest bit of damage I can see is that the curved plastic cover that goes over the electronics / motors has a big crack that's been glued back together. Also the plastic tabs that the restraining screw go into appear to be broken / missing on one side. I think that a previous owner didn't realise that you have to remove the flat side panel over the gears to be able to remove the curved top cover :S

I think that my big concern is that this damage might have been caused by it being dropped, though there's not much sign of damage elsewhere to back up that theory. And now that I think the electronics are playing nicely my remaining concern is that there could be something bent internally. Manually rotating the axis' seems to be pretty free, though both have a point in the rotation where it's a bit stiff. Is this normal?

I probably need to strip it down somewhat to have a further poke around inside. Has AstroBaby got a guide for that?

Fingers crossed I have landed myself a good hefty mount for my imaging efforts, but I just want to make sure it's all pukka before I part ways with my EQ3-2.

Any advice happily received!

[Breakintheclouds]

Yes, Astro Baby is your trusty guide in these matters:

HEQ5 Strip Down Guide

[samtheeagle]

Yeah I found that one ta... Looks pretty darn scary, but I'm going to have to do it given the rather unknown condition of the mount atm. My fear is that I'll never get it back together and working again...

I've defo got a bit of a nasty noise on one axis, which strangely changes it's intensity depending on the speed the handset is set to, but it's actually quietest on 16X which is the opposite to what I'd expect.

[Merlin66]

Is there any "slop" in the noisy axis?? ie if you lock the clutch and then try and rotate the head back and forth? The noise could be as "simple" as the worm engagement.......

[samtheeagle]

No, slop doesn't seem to be a problem, at least not with the clutch engaged. When I release the RA clutch and attempt to manually rotate the axis there's a good few mm of play before I can feel a contact against another lump of metal. Dunno whether slack with the clutch disengaged makes any odds or not?

The unpleasant noise seems to be coming from the motors rather than anywhere else I think. At 16X speed on the handset it's just a nice clean purr, but at 8X and 2X there are some rougher sounding noises. I hope this isn't a sign of a bad motors? :S The DEC axis has similar noise characteristics, so maybe it's just the noise made by the motors at lower speed?

I'm hoping for some clear sky tonight, so I can try and use the mount in anger. Maybe grab a few quick images to get a feel for the tracking ability. So I guess an important job to do now is check out the polar scope alignment!

[Astro_Baby]

Dont be afraid of stripping it down - allow plenty of time and patience and all will be well. My guide covers all of the things to look for.

The noise could be one of a number of things;

Bad worm engagement

Bad motor to worm engagement

Motor resonance (the mounts just like that)

Ids this a Syntrek / GoTo version or just the basic version. I assume basic in which case the mount is a lot less fussy on its worm gear set-up.

[samtheeagle]

Yeah, it's a basic Sky-Watcher HEQ5. And thanks very much for your guide(s), they're a massive help!

[Astro_Baby]

No worries - if your anywhere near me at Gatwick I am happy to offer any help if your stuck.

If you do end up stripping the mount allow lots of time. I did mine in 4 hours BUT the firts time round it then took 3 days to align the worm enagement

Other people who have followed the guide report it taks much longer for them. Its reasonably straight forward.

I wouldnt want to depress you but my sister bought an HEQ5 off ebay without asking me and the mount was a dog. It was full of problems. I got it going for her but it really was a project and I had to get an engineering firm to do some of the work like replacing some of the threads with helicoils because I dont have the facilities for that kind of thing.

Assuming no one has busted anything inside its quite straightforward though and just needs patience.

[samtheeagle]

Thanks for the kind offer, but I'm not really local to you... I'll soldier on and fire questions in your general direction when the time comes if you don't mind?

I think my biggest concern is that something fundamental might be bent. I'm not sure how possible that is in such a hefty lump of metal? I popped the polar scope out earlier on and looking through the hole whilst rotating the RA axis there did seem to be a bit of a wobble at the other end during the rotation, but it's hard to know what is within acceptable tolerances with this being the only one I've had... I think I need to strip it down just for my peace of mind, I'll be concerned that there's some nasty issue festering and getting worse in there otherwise :S It's the variable stiffness when rotating the axis' that's nagging at me. Surely it should have a uniform resistance through the rotation?

But all that said, I've just got back in from a bit of a test session and things are looking pretty good thus far. I tried 1, 2 and 3 minute subs, all unguided, with a very rough and ready polar alignment, and have got good results I aimed at Regulus which is pretty low down atm, and I understand that would make it more prone to trailing, but in actual fact the stars are pretty tight. A little egg shaped, but nothing too major.

I can totally understand why people go on about these mounts being great for imaging So long as I can put my concerns to rest I'm going to be a VERY happy bunny with this lovely hunk of metal.

[Astro_Baby]

The stiffness in one part of the rotation suggests the worm gears arent engaged perfectly. There is always a little bit of stiffness in one part of the cycle or else a little play. These things arent super precision in that respect.

When you take it to bits anything thats busted or bent will be pretty obvious. Do bear in mind though (and I cant stress this enough) tuning this things after rebuild can be VERY time consuming so dont rush it.

[samtheeagle]

Yeah, I'm kind of getting the time consuming vibe from people Good to know that there should be at least some resistance as part of the cycle, but my gut feeling is that there's too much right now.

So I'll let you all know when I'm about to take it apart, because it's almost certain to coincide with an unexpected spell of spectacularly clear nights!

[samtheeagle]

So, I spent pretty much the whole day yesterday taking the mount apart, cleaning it up and putting it back together again. Now I'm no engineer, but as best as my untrained eye could tell everything is in good shape, nothing seems bent, and there didn't appear to be any wear or such like inside. The axis' rotate much more smoothly now, and there's a uniform resistance during the rotation, so I hope that means that I've managed to engage the worm gears correctly. I can't feel any play either, so hopefully I've got pretty close to the sweet spot...

So I think that I can finally say that I'm VERY happy with getting a really good deal! w00tage!

The only other things I'd like to do are replace some plastic bits. I'm missing the two plugs that cover the float adjusters, and for some reason the previous owner decided to cut an ugly hole out of the polar scope cover! Anyone know if these kind of things can be purchased?