Trouble with SkyScan EQ5 Mount - Park and Home

[boyjs1]

After buying a SkyScan EQ5 mount (and an 8" Newtonian) in the autumn, I finally found a couple of clear nights this week to try the alignment process. After an initial semi-success, however, it's all gone pear-shaped. I try to do the 3-star aligment, but the telescope always ends up way off. I have tried various stars, but to give you an example, Sirius is the first star the controller suggests, the telescope slews, but ends up pointing about 60° E and 20° S of Sirius.

I've read with interest the postings about Home and Park positions, because it seems to me that the mount's initial point of reference is wrong.

But what's not clear to a very literal reader like me, is whether I can ever re-set the Home and Park position to be identical i.e. weights down, OTA straight up, facing Polaris? I see talk of sticking tape on the dials to indicate the previous park position and it all seems a bit primitive, given that the software must be reasonably sophisticated.

I'm pretty sure that at some point I have screwed up the EQ5's point of reference by moving the tube manually, or by telling it the Park position is looking at Arcturus, or something, rather than Polaris.

Can anyone help? it's to be clear again on Saturday night and I want to be able to track Mars properly before it fades!

[steppenwolf]

Unfortunately, the Home position really is that crude despite the rest of the hi tech features of the mount. Crude but you HAVE got to get it right! Here are some typical things to check.

1. That you have calibrated your polarscope

2. You are properly polar aligned

3. You have tried really hard to get that Home position right, weights down, telescope pointing up - NOT at Polaris, just up at its highest point

4. Date entered in the correct format - many mounts use American date format of mm/dd/yy instead of dd/mm/yy

5. Time correct?

6. Time Zone correct (0 for the UK)

7. BST/Daylight Saving turned off (for now!)

Moving the mount manually is no sin, I do this all the time.

Try setting up inside in the comfort of your own home aligned with North with a compass, run a planetarium program to determine where things are in the sky and see if your mount slews to somewhere at least approximating where it should be.

Next real session, slew to the first star and then unlock the RA and DEC clutches and MANUALLY push and pull the tube until it is centred on the first star then lock the clamps and do the rest of the alignment for the other two stars using the hand controller.

Good luck.

[boyjs1]

Thanks for that. I have tried what you suggest, but with no success. I have gone back to the start of the set-up guides, as I obviously have made some basic error somewhere. I have a very naive question here: when using the polar aligment telescope, is it crucial and utterly imperative that the Plough in the viewer be in precisely the same position as the real Plough in the sky? I'm wondering if that's why you can set North, but Skyscan can't then find east and west. Last night the mount was looking for Arcturus on the ground when it was high-ish in the E. I moved it to Arcturus manually, then the second star was Capella which it hunted for in the NW, but the tube hit the mount, the motor started buzzing and it was all a disaster. I came in after 2 hours and hit the brandy.

[andyf]

I have the same mount which I use with a Skywatcher 100 ED. I've used it for the last 3 nights all with 100% sucess. I sight Polaris through the polarscope and just centre it in the crosshairs irrespective of its 'real' position. This seems accurate enough. The counterweight is pointing down and I usually roatate the tube in the other axis so that Polaris is in the telescope's eyepiece (though not centred). I choose a 3 star-align currently using Aldebaran, Tsih and Castor. Each of these are not within the eyepiece when the mount does it's initial slew but are not that far away. I use the hand controller to centre them.

As I say, it's very accurate after this align. Your co-ordinates, correct time and date (especially format) are far more important than precise polar alignment.

[steppenwolf]

Last night the mount was looking for Arcturus on the ground when it was high-ish in the E.

Even if your polar alignment was not perfect, you would not expect an error of this magnitude so clearly there is something else very wrong. Are you sure that you have entered your latitude and longitude correctly as this is very important?

Did you buy the mount new or second hand? If second hand, is it black or white?

[boyjs1]

My latitude is 52 degrees 7 minutes north and my longitude is 4 degrees 17 minutes east. I'm sure that's entered correctly, with longitude first and the compass points entered as E and N. The mount was purchased new (it's a black one). The thing is, the very first time I tried the aligment, it did work, more or less, using Sirius, Mirfak and Arcturus as the 3 stars to align on. I then selected Mars as my first GoTo object to view, and the telescope slewed to very close to it. But I tried then to re-align and that's when it all went wrong. I suspect what went wrong was a combination of switching the power off, moving the mount manually and screwing up the Home / Park positions. It's to be clear again tonight, so I'll have another go, but I don't really know where to start now.

Just discovered the hand-controller to PC link uses one of those archaic serial RS 232 cables. I've got no matching port on my PC, so it's off now to buy an adaptor. Mind you, I don't suspect the software. The problem isn't the 'scope, it's the numpty operating it.

[jobe]

i'm having similar problems to you.

i suspect there's something i'm doing wrong but the more i triple check the settings keyed into the handset the more i have no idea.

jobe

ps you shouldn't need to open the clutches to move the scope, just use the slew keys. don't forget to adjust the rate at which it slews with the number 2 key.

[boyjs1]

So nice to hear it's not just me who finds the whole set-up process problematic! I'm waiting for it to get dark now. I've just upgraded the hand-controller to 3.27, but I don't see how that would help. But it may have caused some stored setting to be re-initialised. (Can you tell I'm getting desperate...?)

[jobe]

does your handset freeze at all?

what about when turning it on? does it always connect with 1 beep?

jobe

[boyjs1]

No, the hand-controller doesn't freeze. It seems to behave. It's just the mount which is giving me trouble.

[steppenwolf]

ps you shouldn't need to open the clutches to move the scope, just use the slew keys. don't forget to adjust the rate at which it slews with the number 2 key.

Manually moving the mount by unlocking the clutches and manually moving the telescope on the first alignment star ensures that the system believes that it started from a 'perfect' Park position.

[jobe]

Manually moving the mount by unlocking the clutches and manually moving the telescope on the first alignment star ensures that the system believes that it started from a 'perfect' Park position.

ah. didn't know that. sorry for the duff info.

i just thought that by moving it with the direction keys the 'brains' would adjust better.

jobe

[steppenwolf]

i just thought that by moving it with the direction keys the 'brains' would adjust better

Your logic is fine but the PARK position is such a poor (and not necessarily repeatable) start point that if you can 'fool' the system into believing that the PARK position was indeed 'perfect' you have a much better chance of getting accurate GoTos.

[boyjs1]

Thanks, all of you, for your advice so far. At about 1 a.m. this morning, I discovered that the SynScan upgrade (to 3.27) adds a new feature: Restore Factory Settings. I parked the scope, did a re-set, entered all the information again, and tried a 1-star alignment, just to test it out. The 'scope slewed to Arcturus, its target. It could then find Saturn (more or less), using the hand-set. As it was getting late, and I wanted to end on a good note, I didn't try parking again, and re-aligning on 3 stars, which will be my goal as soon as we have another clear night.

HOWEVER, I still have a problem! The motor is making grinding noises, and I can't use the hand-controller to steer up and down. I just get a horrible grinding noise if I do. Does something need oiled, perhaps? Or is it the cold and damp? It was pretty cold here last night.

[boyjs1]

As a short follow-up to this saga: I visited the dealer with my mount yesterday and he fixed the grinding, buzzing noise. It was due to a faulty Dec cable! It seems that the cable wasn't allowing enough power through to the motor.