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ahhhhh so frustrating!!

My setup was working so well last month! All I had to do was open up my obsy cover and start imaging...now PHD is doing some weird things in the Dec axis, but nothing has changed?

This issue was raised recently but no answer was found..I'm posting again just encase we've missed someone with the answer.

As you can see from the pictures PHD will go through the calibration albeit not very well - firstly it's taking to long despite that I've tried upping the calibration step to 4500ms anything over that doesn't make any difference? Also when calibrating the East-west the star doesn't come back to the cross-hairs and almost looks as if it's moving properly at first and then retrograde although it's still just doing the one direction I.e East (if that makes sense?) I've attached a pic of that too.

Then when clearing the Dec backlash it gets to '1' and quickly moves on to RA?

And when calibration is complete as you can see the Dec falls off and doesn't return. This happens to the North as well depending on what side of the pier I'm on.

What is going on here!? I spent 5hrs last night trying everything I could think of: reinstalled PHD, tried a different computer, new power supply to mount, rotated the camera, checked and changed cables, checked polar alignment, Balance, changed PHD settings, but nothing worked. I'm really at a loss!

All the PHD setting are as default except from the calibration step which as I said I raised to 4500ms.

I'm using: HEQ5, EQDIR, ST80, DSI, EQMOD and PHD for guiding.

someone please please help me with this!

Thanks,

Michael

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Edited by msinclairinork
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About the only thing I could think of would be a cable problem of some sort... Might be worth putting up a screengrab of the PHD settings, the Ascom settings for the camera and the mount and the eqmod settings.

I very much doubt I'll be able to find the answer (so far, touch wood, I'm in the same boat you were, most of the time it just works), but they may help someone else spot the issues.

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In the expanded EQAscom control panel there are settings for guide pulse (not in front of EQMod so vague instructions I'm afraid). These range from x0.25 to x1.0. These will affect the number of calibration steps and how far they move the mount each time. I have to set these differently for different focal lengths of guide scope i.e. for my finder-guider I set to x0.75 or x1.0 depending on how close to polaris I'm looking, whereas with my OAG (1200mm FL) I set at x0.25.

As John says, I would also suspect a cable problem if you are using the ST4 port to guide. I had problems where it was not guiding in one direction and calibration usually stalled, but then it said it was guiding, but in one direction it wasn't. For me that was an intermittent dodgy connection of RJ12 plug into the mount. I cut off offending plug and re-crimped on a new one (thanks to Maplin £10 crimp tool & plugs) and all is good now.

Edited by FrankieValley
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I meant to say that I set the 'brain' calibration steps to 1500 for my finder-guider cause it's a very short FL and to about 1000 for my 1200mm FL OAG set up. I usually aim for ~10 calibration steps in any one direction. I try and set the camera exposure to 1 second for calibration if the stars are not too dim in PHD. This all means calibration takes a minute or two. I then change the exposure setting to 2 seconds so PHD isn't chasing 'the seeing'.

If you 'calibration step' in the brain is too high calibration takes ages, cause you are waiting (4.5s in your case) for not much to happen/move. If the exposure time is high during calibration then PHD has to wait between frames twiddling its thumbs :-)

Edited by FrankieValley
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Thanks for the info. I suspect this will likely help speed up the calibration process..but I'm not so sure it will fix the problem..I will certainly give it a try though.

Could be a cable problem...I'm using the EQDIR interface and do have spare plugs and a crimper so worth a go!

Thanks,

Michael

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You can use the manual guide controls under PHD to verify the correction signals are in fact getting to the mount....

(BTW I see you have v1.12 - there's an upgrade available to V1.13.0b)

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You can use the manual guide controls under PHD to verify the correction signals are in fact getting to the mount....

V1.13.0b)

This is good advice and will show up any bad ST4 connectivity, but I would add that you should make sure your mount is 'tracking' when using the manual guide buttons and listen to the motors as the movement will be too small to detect. The 'tracking' part is important, because pressing the West guide button will do nothing if the mount is not tracking. In the West direction I suspect the guide pulses negate the RA sidereal tracking pulse and it simply halts the RA Westerly motion when guiding. When the mount is not tracking, West will move it nowhere, which can seem like a problem but it isn't :-)

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Thanks for the comments guys. I'm using a DSI straight to the laptop. I wasn't aware of the new version available so I'll be trying that.

I've been on the stark-labs yahoo group and it seems to be a common(ish) problem. Some suggest upping the 'Max Dec duration' from 150 to 1500. So another thing their to try.

I'm getting more compelled to buy a copy of Astro Art as folks seem to get on better with it...I'm getting desperate - to many clear nights waisted now :)

Thanks,

Michael

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I seem to recall someone on here having an issue with v13, and needed to update Ascom to the latest release (v6?) to resolve... just something to watch for.

Edited by jgs001
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I've been on the stark-labs yahoo group and it seems to be a common(ish) problem. Some suggest upping the 'Max Dec duration' from 150 to 1500. So another thing their to try.

Hi Michael,

I think that increasing the declination duration is only if your polar alignment is really bad and the motors are unable to keep up with the drift when pulsed at 150 each time. In an ideal and perfectly polar aligned world, there is no need to guide in declination.

PHD has another useful tool to watch which is the bottom bar. When it is calibrating this is where you see it telling you how far it has moved, how many steps, etc. It is also useful when it is guiding, because it will tell you how long a pulse it sends, in which direction and how far the star moved. It can give you a sense of what is going on.

It has taken me 3yrs to get to a stage where I have some idea of what PHD is doing. I only achieved repeatable, long exposure 'round stars' 3 months ago! I tried everything and I mean everything, but it really came down to a mis-match of focal lengths between guider and imager..... and some cable/connectivity issues thrown in just to really make things difficult (like they weren't already).

The problem is not PHD, because that does work and I'm not sure another guiding software will be able to get around the issues you have.

Stick at it and good luck. Let us know how you go. Here to help :-)

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