RA and Polar Aligning.

[Tandum (Robin)]

Can someone explain to me how RA and DEC interact when polar aligning. I'm having all sorts of weird stuff happening here when dialing in the EQ6 which I've never seen before. I would have thought RA would be constant, I don;t see how alt/az adjustments effect RA.

I just can't seem to get it to align and it seems to me that RA is running slow. If I dial in a custom RA it all looks good but I've never had to do that before. I have the camera x/y aligned pretty close to the scope and used PHD tonight. I shot down the pub for a half hour and left it collecting a PHD log for PEC and when I got back, DEC was right on the line but RA was half way down the screen. Oddly enough, both RA and DEC where off the graph but DX was on the line. I had guiding off.

I have just regreased and tuned the old eq6 and pe was around +/- 6 which is really too good to be true. I'm lost. I thought I'd move to a short FL scope and try again.

[bert (Brett)]

Hi Robin,

Make sure your worms arent too tight and stalling. I did a lot of work to get the worms just so on my mount. What I found was...

1. Get the load that you are going to use on the mount and get it balanced.

2. take the pcb out and take the ra motor out.

3. check the worm spacing by spinning the spur gear with your finger inside the mount. IF it binds up or is tight adjust the worm as needed.

Brett

[Tandum (Robin)]

I thought I had the worms set ok Brett, but I'll have another look. I don't understand why DEC drifted off the graph in the opposite direction to RA yet the star was still right on the line on screen and dx in the other graph was right on the line. There's some maths being done between ra and dec in phd I think.

[Tandum (Robin)]

Not the worms Brett but it looks like something in RA is catching, I'll have to pull it apart again I guess, might just be a worm roller bearing. I plugged the handset and guiding cable in instead of eqmod and I could see it drifting at regular intervals, almost like a step function. I also found that the RA drift was being recorded by PHD when it was calibrating DEC which is why both lines on the graph where doing similar things. Looks like rain for a few days anyway.

[adman (Adam)]

Keeps you on your toes though! Was there a particular reason that PHD was mixing up DEC and RA?

Adam

[Tandum (Robin)]

From what I've found Adam, the RA/DEC graph is corrected for angular offsets in the camera while the dx/dy graph is not. So phd thought the RA drift was the camera plugged in in at an angle.

[Tandum (Robin)]

Who put that drift compensation slider into eqmod. It needs a tickbox to lock it, mine was way over to the left.

What a duufus ... Don't ya just love wasting 2 weeks chasing non existent hardware issues.
I think I might get some white lights in the obs after this one.
Trying to read red text on a red background under a red light just doesn't work.
I still can't see any numbers in that box, I thought it was busted in this release .....
Black on white for text just works ....