CG5 ASGT : Poor calibration on South

[SeanKOR]

Dear all,

I just joined SGL, I hope I share the valuable information with you all.

As stated in the title, I tried to complete calibration with CG5 but I faced some problem in South step.

Mount : CG-5 ASGT

Main tube : Megrez90

Guide program : PHD guide

Guide tube & cam : ST80 + SSAG

W, E, N calibration works smoothly, Green box was moved and back normally. But the box doesn't move in South calibration step.

So I expected "DEC Calibration failed..." due to no movement in S-calibration, but guide finished without any error and starts guiding.

There're 15 steps move for 3 directions (W, E, N) but the step increased without move in S. Actually there's very small move (1~2step only) in the final step of S calibration.

I check the cable, SSAG, Program in laptop, but no problem found. It seem that some problem is in the mount.

And mount works fine with hand controller.

Did you experience this situation?

Attachment shows that DEC graph is getting decreased when guiding starts.

thanks and regards,

/Sean

무제06.tiff

[B_ickringill]

Hi Sean

I am having exactly the same issue. I too have checked all the cables have a reasonable polar alignment but phd will not move in dec south. I have read that it could be due to a large amount of backlash in the dec worm gear. I have taken my mount apart and thought I had sorted this but still get the same issue.

I am going to try moving my mount slightly east so phd will only have to correct north, but this is far from ideal.

Good luck

Brendan

[B_ickringill]

Had a few hours of clear skies tonight.

I managed to get guiding by spending a long time drift aligning and then switching phd to auto. If I left it on eq north it would not work but auto sorted it.

Strange but true. I still had a shaky graph but it was much improved.

Brendan

Celestron c6 ngt on cg5

[Uranium235]

Sean, I fear you may be at the very limit (or over) in weight of what that mount can cope with. You would have a much easier time if you ditched the ST80 for a finderguider. Another good idea is to avoid off-axis guiding with the CG5 as it doesnt seem to like it one bit.

Firstly, you need to check whether its a connectivity problem. First, go to the brain icon and change the calibration step size to about 3000 (this will move the mount enough so you can see it onscreen). Close that, start a loop then go to manual guide mode. Then keep tapping the south button to see if the stars onscreen (or via your imaging camera) move, if it doesnt move you know its a duff cable or dirty socket. To validate it, tap the N,E and W buttons to see if you get movement - taking into account any backlash you may have to overcome before the mount moves (not so much in E/W, but usually loads in N/S).

If its the cable, get a new one (prefarably two!), if not the cable then have a look at the ST4 ports to see if there is any crud in there.