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PHD graph - Something odd going on.


swag72
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Hi Folks, well it's all going Pete Tong today and has been for the last 4 days. I hope someone can shed some light on my latest problem.

PHD calibrates fine, I can hear everything ticking away as usual, so far so good. It does an OK run for a while, red and blue line bobbing along the middle nicely, then for no reason at all (none that I can fathom) the RA (blue line) shoots off towards the sky, never to be seen again. The only way back is to stop the guiding, restart it and clear the graph.

1) I have restarted PHD

2) I have changed the ST4 cable around

3) I have disconnected camera from USB

4) I have recalibrated

Not sure what else to try now. At this moment as we speak it's OK. Don't know for how long though. I have not changed any settings since it was working absolutely fine 4 nights ago. Things have just gone haywire for some reason.

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No cables dragging - Working OK at the minute still. Just can't understand why it keeps happening.

Just happened again - Can anyone point me in the direction of eliminating where the problem lies?

I have disconnected Stellarium, so using the mount for goto.

Edited by swag72
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I have no ideas as to your trouble Sara, but if I also fell out with PHD over the last couple of weeks. After a year of trouble free guiding it decided not to co-operate for no apparent reason - just won't calibrate. Very frustrating.

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I think I must be one on the lucky ones...

PHD just works for me - no concerns - no issues.

I see the graphs on this thread and some shown on others and the ONLY time I've seen anything similar was when I was using the wrong ST-4 cable...

When it appears to shoot off the graph...what's happening on the screen? Is the target star still sitting on the same X-Y pixel?

I can only think that somehow the correction signal from PHD via the camera to the ST-4 port on the mount is not getting through...

I assume no cable wrap problems, good balance, reasonable PA etc etc

When this happens (on your graph) do the manual PHD corrections still work?

I'm using V1.12 with Carte du Ciel and either the NEQ6 or Lx200 mount.

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When it appears to shoot off the graph...what's happening on the screen? Is the target star still sitting on the same X-Y pixel?

I can only think that somehow the correction signal from PHD via the camera to the ST-4 port on the mount is not getting through...

I assume no cable wrap problems, good balance, reasonable PA etc etc

When this happens (on your graph) do the manual PHD corrections still work?

When it shoots off the graph, I lose the guiding star. How can I check manual PHD corrections?

I don't have any limits set that I am aware of - The scope was facing very much in the up position and the camera was near the tripod, but it never stopped the movement. Where can you set the limits in PHD? Is there some set by default?

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Where can you set the limits in PHD? Is there some set by default?

I use EQMOD and mine are set there. Not sure if you're using EQMOD or a handset, and if you're using EQMOD, I'm also not sure how/if limits are applied if you guide using ST4 rather than pulse guiding through EQMOD. More questions than answers I'm afraid.

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I wouldnt think its PHD causing the problem - the graph is just reporting what is happening as it happens, If the guiding is reasonable for a while then shoots off in one direction its probably something on the mount shifting - scope, camera, cables, clutches?

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I finished with sending back the CGEM, It would guide for a few minutes then fly off the graph.I swapped it with a Skywatcher NEQ6 Pro SynScan. Now it guides like a dream..

Nadeem.

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You can always check if the correction signal from PHD is getting through to your mount by pressing the manual controls (Tools/ manual control)

If nothing happens then the mount is :

a. Not receiving the signal - check cables/ connectors

b. Receiving but not actioning - balance/ power/ etc

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Thanks for all this folks. I will have a go when I return from UK next week. My concern is that it is the mount, but we will wait and see.

Will look into the limits on the handset. As I said it was at a pretty upright angle - Does anyone know if the handset has limits set by default?

Edited by swag72
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I had the same sort of problem recently when tracking at the zenith. It appeared to be slop in the gears, and biased balance seems to have cured it.

Edited by Freff
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Bias balance? Which way is that?

I usually go for looking in the same direction as the scope and if the weights are on the left then make them heavier.

So imaging at the zenith can cause this problem?

Edited by swag72
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Imaging at or near the zenith seems to bring all sorts of niggles out in my guiding too although not as bad as you seem to have. You want to unbalance things slightly keeping the east side heavy i.e. if the scopes on the west side of the mount move the weights out and if it's on the east side then move the weights in. With your RA guiding going off like that it would seem that the mount just can't keep up for some reason - it's worth checking your clutches are nice and tight too ;)

James

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Bias balance? Which way is that?

I usually go for looking in the same direction as the scope and if the weights are on the left then make them heavier.

So imaging at the zenith can cause this problem?

Sorry Sara, that was an oxy-moron. In my case I off balanced it at the OTA base.

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