HEQ5 - Dec Drift...

[PhotoGav]

After a forced absence from the telescope I braved it yesterday evening and set up to try and get everything up and running again. Needless to say it wasn't quite that easy! I had niggling trouble trying to get PA back on and then struggled with aligning targets using PointCraft and AstroTortilla. Nothing really badly out, just struggles to get there. Anyway, I finally was satisfactorily on target (M13) and fired up PHD2. I noticed during the calibration process that E/W was fine, but N/S struggled again - when going through the South Steps, the guide star didn't move at all. Louder alarm bells started ringing. So, it was calibrated and started guiding, but here is the resulting graph:

No, that's not right at all....!

I had a quick look around trying to figure things out and noticed in the scope details section of APT that the Alt & Az figures were changing as usual, but so was the Dec figure. RA was nice and steady, but DEC was definitely increasing. It was at this point that I decided there was no way that I was going to have the stamina to sort out a solution there and then, so to bed...

Does anybody have any ideas as to what could be the cause? And any ideas for a solution, please?! The mount was slewing about quite happily, both under computer control and 'manually' through the EQMod mount interface. The problem presented itself when trying to make adjustments in a plate solve and in PHD2.

I look forward to your feedback.

Thank you.

[supernov]

To me it looks like both axes are behaving really steadily, never had my RA look so nice. DEC isn't jumping around either, to me this seems like a polar alignment problem.

[PhotoGav]

To me it looks like both axes are behaving really steadily, never had my RA look so nice. DEC isn't jumping around either, to me this seems like a polar alignment problem.

OK, that's interesting, thank you for the feed back. I did struggle with PA, so perhaps I will just revisit that when I get the opportunity and see how things change.

[ollypenrice]

That is so extreme that either PA is absolutely miles out or PHD is actually driving the Dec into error actively. 

In your description my gut reaction is that there is too much software at work here! I would do a simple and very quick drift alignment first, or at least do a drift test of your software-derived PA. Instinctively I think it's more than that, though. I suspect PHD is driving the wrong way or something like that.

Olly

[PhotoGav]

Thank you Olly. You are right, I think a 'back to basics' approach is going to win here. It has been a while since I have used the system and I was also trying out the new version of APT with it's new plate solving feature. My PA routine was not as smooth as usual, so I am hoping that the problem does come from very poor PA. I much prefer that option to what I feared - a broken mount. I will report back once I have had a chance to try again...

[ollypenrice]

It won't be a broken mount. If you had no working Dec drive at all and were polar aligned it would be much better than what you have.

I only tried PHD2 once. I've used the orginal and normally use AstroArt but I vaguely remember it doing something similar, driving the mount off away from the correct Dec position. I can't accurately remember though.

As I say, I don't think that's drift, I think the dec motor is being driven away. I'd put a tenner on it but not a hundred notes! 

lly

Edit. The obvious test would be to disable guiding in Dec, of course, to distinguish between a guide pulse inversion and drift...

[Thalestris24]

Hi

Yeah, PA and balance both worth checking. I get the impression that it didn't calibrate properly even if it thought it was done. Also wondering what DEC algorithm you were using?

Louise

[Starlight 1]

I do not know alot about this, But that Star do look a long over to the left ? or is that were it ended up after Dec stop working.

[supernov]

I've never seen PHD correct in a wrong direction actually, that would be rather unusual. I see you're using EQMod, did you properly set the focal length of your guide-interface in the brain-section of PHD2? Together with pixel-size of the camera, you can calculate the needed pulse durations. This, however, depends also on the sidereal rate that is used for corrections, which you can also set there. That sidereal-rate has to be set in EQMod as well under the pulseguide settings. This then should give you good movement.

I'd advice to give alignmaster software a go, do PA with both axes at the same time (uncheck to use axes seperately and uncheck sync) and put the stars right in the middle. This gives me a pretty great PA right away already, repeat that 2x maybe and you should be very close to perfect, just having the pointing error of the goto system still in it, but fine enough for active guiding. Like this, I get proper PA within 5-10 min.

[PhotoGav]

Thank you for your thoughts, all. I'm pretty sure that it will be a simple case of PA being miles out. I hope to be able to see the stars in one of the next few nights, so will have the chance to try everything again.

[PhotoGav]

I finally had the chance to have a play with everything last night and made a couple of discoveries...

Firstly, my PA was indeed off, so that was swiftly dealt with and things were looking good. However, when I calibrated PHD2 I noticed that again there was no movement of the mount when going through the South Step part of the process. The guide graph was significantly better, but soon began to slip gently South. I opened up the Manual Guide panel (not straight away, there was a degree of tail chasing in the dark involved before it struck me that it might be a good idea...) and sure enough clicking the North, East & West buttons caused the mount to move a little, but clicking South had no effect what so ever. Moving the mount from the EQMod control panel works perfectly in all directions. So my second discovery is that my mount is broken and I have narrowed it down to the Autoguide port. What I haven't done yet is to try another guide cable, though I am sceptical that the problem lies in the cable.

Does anybody have any experience they can share of fixing a guide port on an HEQ5 please? Is this a case of contacting FLO and sending the mount head in for some professional TLC?!

Damn gremlins... It was a lovely clear night last night and nothing useful was done... Frustrating...

[PhotoGav]

And another update...

I got the screwdrivers out and opened up the electronics area of the mount. I couldn't see any obviously damaged cables. I then struggled to put it back together again. I carried out a test to see what further damage I had inflicted, but to my amazement EQMod control panel drove the mount in all directions perfectly. I then opened PHD2 (not many guide stars in my dining room at 9:45am today), connected up, opened the Manual Guide panel and hey presto, North, East & West all working perfectly. What is truly astonishing is that the South control also works now! I have absolutely no idea what I have done to 'fix' the problem, but at this stage it would appear to be working when before it wasn't... Now all I need is another clear night sky to test it out properly. Fingers crossed!

[swag72]

I would consider a new EQDIR cable..... I say that as my HEQ5 munched its way through a number of cables..... It would manifest itself in dodgy guiding, odd slews etc. I always had a spare cable knocking around for this purpose.

That's certainly where I would be looking.

[ollypenrice]

Yes, cables are aften faulty despite looking OK.

Olly

[PhotoGav]

Thank you Sara & Olly. I tried both an EQDIR cable and going through the Synscan handset and the problem manifested itself with both. I was using the EQDIR cable this morning when it was working properly again. I'm fairly sure that it is a dodgy solder joint or cable connection somewhere in the mount. My fiddling about has been sufficient to make the connection again. The problem is how long will that last?! All in all this puts two items right at the top of my 'wish list' - an observatory, to keep everything out of the elements (the mount is left in the garden under a tea-towel, a bin bag and a heavy duty BBQ cover, which is obviously not enough to keep it happy) and a new mount (thereby hangs a whole new thread... Which mount - Avalon Linear Fast Reverse, Mesu 200, an EQ8 or just an NEQ6? Trouble is I rather like my HEQ5!). Whatever, I smell more cost if I'm not careful!

Yes, cables are aften faulty despite looking OK.

Olly

Olly - Trying to work out which regional accent 'aften' would be - West Country perhaps?!

[Thalestris24]

Thank you Sara & Olly. I tried both an EQDIR cable and going through the Synscan handset and the problem manifested itself with both. I was using the EQDIR cable this morning when it was working properly again. I'm fairly sure that it is a dodgy solder joint or cable connection somewhere in the mount. My fiddling about has been sufficient to make the connection again. The problem is how long will that last?! All in all this puts two items right at the top of my 'wish list' - an observatory, to keep everything out of the elements (the mount is left in the garden under a tea-towel, a bin bag and a heavy duty BBQ cover, which is obviously not enough to keep it happy) and a new mount (thereby hangs a whole new thread... Which mount - Avalon Linear Fast Reverse, Mesu 200, an EQ8 or just an NEQ6? Trouble is I rather like my HEQ5!). Whatever, I smell more cost if I'm not careful!

Olly - Trying to work out which regional accent 'aften' would be - West Country perhaps?!

It might be just the corresponding solder joint on the board so easy to fix. Or could be the actual connection - either at the plug or the socket.

[swag72]

 Which mount - Avalon Linear Fast Reverse, Mesu 200, an EQ8 or just an NEQ6?......

Exciting times ahead then Gav!!! 

[PhotoGav]

It might be just the corresponding solder joint on the board so easy to fix. Or could be the actual connection - either at the plug or the socket.

'Easy'... Mmm, from my brief investigations yesterday I don't think any soldering would be easy on the board, mainly because I am very inexperienced when it comes to soldering and also because there is very little room for manoeuvring in there. I admire your optimism though!

Exciting times ahead then Gav!!!

Mainly in my pipe dreams... If only I could agree with the rest of The PhotoGav Family on an acceptable location in the garden for an obsy, plans could start to come to fruition! I can be very persistent when required though...!

[PhotoGav]

Progress at last...

On the suggestion of Steve at FLO to try a different ST4 cable before sending in the mount, I set about fiddling with the setup a little earlier this evening. A different ST4 cable didn't make any difference, N, E & W all worked in the manual guide control panel in PHD2, but S still did nothing. I tried plugging the cable into the QSI camera and connecting up with PHD2 - hey presto all four directions worked perfectly. I tried connecting my ZWO camera to the mount through PHD2 and again, all four directions worked perfectly. So, I hereby conclude that my guidecam, a Lodestar X2, is to blame in all of this and has a faulty guide port. I've been on to IKI, the vendor of the offending article, for advice and await my instructions...

Thankfully it seems that I won't have to give up the mount for repair and can try using the ZWO for some actual guiding.

Now all I need is the time, late night energy and clear sky to give it a proper test run!

[supernov]

Nice research there! Also thanks for sharing as this puts another possibile cause to my list of possible causes, whenever I'll be faced with them. In the end, a very methodical approach like you did works best.

[PhotoGav]

Thanks @supernov.

My latest state of affairs is that I spoke with Starlight Xpress regarding the Lodestar and the very helpful chap on the phone recommended that I use a small jewellers screwdriver to push up the metal connectors in the autoguide port on the camera so that they make a better connection with the plug. I have done that and even had the chance to test it. The miracle is, it appears to work perfectly now. I am slightly apprehensive as to how long it will work for and I fear that it will lose connection in the middle of a long run of imaging (no that 'long run' is an expression in use with my imaging at the moment...).

Hopefully that will conclude this thread as a successful solution to an irritating problem!

Clear skies and steady guiding to you all.