Buying a used mount - Advice much appreciated!

[Addy360]

Hello All,

Soon I will be going to check out a black EQ6 mount with a GOTO upgrade and synscan handset for a very good price. I was just hoping a few of you might be able to offer me some advice on what to look out for when purchasing a used mount or typical problems of the EQ6 to look out for. 

Thanks!

[brantuk]

Hi Addy and welcome to SGL

In your visual inspection make sure there are no serious marks or scuffs on the mount head which may suggest it's been dropped or toppled over. Superficial scratches or marks usually amount to nothing other than loading/unloading and porting around. And check there's no dents in the legs thoroughly.

Mechanically check all three legs slide in and out of the tripod with no snagging and the clamps lock off firmly. Check all three feet on the end of the legs. Unlock each axis and check they both move through 360 degs with no binding or snagging/stiffness. Rotation should be smooth and firm. Check the saddle is attached firmly with no chunks out of it or cracks in the metal. Check the altitude bolts raise and lower the head smoothly - ask if it has the bolt upgrade - would be a good thing. Check the az bolts move the head side to side full throw easily.

Electronically I usually ask the seller to plug in and switch on and go through a rough setup. Have them point the N leg north for this using a pocket compass. Note the position of a couple of objects positions using Stellarium for that time of day and check the goto points roughly in the direction of those objects (set alt for that location first). Won't be accurate unless your looking at it by night and do a full alignment.

Listen for the noise of the motors as you slew around using the arrow keys. If you hear any bad crunching on there's any slippage in the clutches it might need servicing. There will be a "small" scrunch as it starts and stops - this is normal. If he has a scope to try out on it (or you may have your own) - balance it up making sure the clutches lock/unlock without undue effort.

I'm sure there's a lot more tests you can do but that should be enough to confirm it's all in working order. Then make your offer based on age and condition. Best of luck with it.

[Geordie mc]

Previous post covers things very well so I will just add check the firmware version. It can be updated but would be nice if it was up to date. Also check the polar scope seems okay.

[Earl]

check to see how much rock there is in the axis with the mount stationary, RA is prone to this, also see if there is and rock 90 degrees to the axis as this an also be an issue, these are easily fixable, but that might not be ok for you.

[Astro_Baby]

Okies heres my routine.  Its pretty thorough but nothing is perfect (more on that later).

First off inspect the mount and ask some questions ?

Does it look about right compared to the answers you are given.  Most of these mounts will show some paint chipping especially on the clutch levers.  Have a good look round and check the paint on the worm covers.  These are the small back round covers.  Do they show any giveaway signs of tampering.  If they do this might not be a bad thing so long as the owner admits it.  You need to adjust the worms sometimes but signs of these being opened and an owner looking sheepish MAY indicate possible trouble ahead...to see how much trouble have a look at the second link below.  It all comes down to the owner being honest and you weighing up if he is or not.

Next up with the mount free of any telescope and weights loosen the clutches and rotate the mount manually through 360' in both axis.  The mount should feel quite light with no resistance.  It may feel a bit like its being pushed through some tar, that will be the lube inside.  If its an older mount it may have the horrid Synta grease in it.  Not a disaster but you may want to strip and clean later.

Next lock the clutches and try gently push each axis.  The DEC will probably be solid and impossible to move the RA may show some give which is normal.  Neither axis should exhibit much play in the way of a loose wobble as though you are wobbling something which has a loose screw. A small amount of play may be evident in the DEC and RA if you wobble them back and forth a bit and thats nothing to worry about so long as its less than about a fag paper of movement.  Mounts that havent been tuned may show some play here and this can be tunes out relatively easily.

Next up check the Alt/Az adjusters.  The one to worry about is the one immediately under the polarscope.  My advice would be to fully extract it and examine it.  These things are a mare and can bend easily and a badly bent one is a pain to extract.  Its not a deal breaker if you don't mind a bit of engineering to extract it but I would definitely ask for £50 off the price at least.  A replacement bolt from Astro Engineering will cost that and it could run dearer if the threads on the mount block have been wrecked.

Now with the clutches locked and no scope present (and no weights either) add some power and make the mount do a slew round 360' in both axis at maximum slew speed (the owner should know how to do this).  Does the mount move smoothly without undue noise (all EQ6s have a start up and wind down rattle and thats nothing to worry about).  During the cycle press both RA and DEC slew buttons and see what happens.  If the mount stalls it will tell you one of the worms is too tight and thats fixable but its good to know now what you might have to be doing later on.

Check the handset and make sure its version 3.  Version 2 handsets are not upgradeable.  Ideally you want a version 3 handset plus a version 2 motor control board. A version 1 motor control board isn't a deal breaker but you may want to ask for a slight discount as it will indicate an older mount.

Now ask the owner to do a start alighn - dont bother setting up the lat and lon just make sure it will run the process.  At the end of it the controller will report a failed alignment because its not real but you are just testing the mount and handset will work ok.

FInally check that all screws and finish is ok on the tripod element and that there are no signs of rust or excessive wear on the thing.  Have a look at the bottom of the legs - they will be a bit of a giveaway as to use. An awful lot of this kit never leaves the lounge buit a well used one will show the rubber spikes at the base of the legs as being worn.

Finally make sure you get the cable with the mount that connects to a PC for software upgrading of the handcontroller - its amazing how many get sold where this is not present and you dont want to have to cough up another tenner for a cable if you can avoid it by just asking the question before you hand over the cash.

The link here will show you the software history which may offer a clue as to age if its software is as standard http://www.astro-baby.com/EQ6%20rebuild%20guide/EQ6%20Development%20and%20Software%20Releases.htm?_sm_au_=isHQk0T5NnsBjM2V

And this link may frighten you as it shows how badly things can be wrong inside a mount but also shows that all but the very worst of them can be resolved.

http://www.astro-baby.com/EQ6%20Demon/EQ6%20Rebuild%20Case%20Study.htm?_sm_au_=isHQk0T5NnsBjM2V

Good luck - dont be too nervous most of this kit is well looked after and there is almost nothing that cant be fixed even if the very worst happens.

[Addy360]

Thank you all for your great replies! I did check all of the things you mentioned and I did end up buying the EQ6 , I'm sure it will be better than my EQ3! Though of course the next few days are forecast to be cloudy.. typical!

[Earl]

As your now the proud owner of an EQ6 are you familar with EQMod?

[Astro_Baby]

Good luck with your new mount and enjoy.  The EQ6 is a very solid bit of kit and will serve you well.

My advice is to ditch the altitude bolts post haste and replace if it still has the factory ones.  The factory ones are shiny and silver and have a hinged lever on them, they are very uncomfy on the hands to adjust and worse still have a tendency to bend and jam in the mount.  A feq uid now to replace will save a lot of possible  heartache later on.

[brantuk]

Glad to help Addy and congrats on your purchase - the EQ6 is a fine mount.

As Astro_baby says - the replacement altitude bolts are a very good idea that will save you money and effort fixing a "bent bolts" situation.