CG-4 mount mechanical problem?

[Chummee]

I have dissembled my CG-4 mount, tuned it, and eliminated any play in the DEC axis (as far as I can tell) but I'm still having guiding issues. It seems that the DEC axis is going in the opposite direction that the pulse tells it to go. There is some drift if I turn off guiding on the DEC axis, but it's nowhere near as bad as guiding being turned on. I use OnStep as my GoTo system. The mount slews perfectly and so I don't think it's a wiring issue with the motor. 

This is the graph with DEC guiding on:

And this is the drift pattern when DEC guiding is off:

This is the log file:

https://openphdguiding.org/logs/dl/PHD2_logs_W46V.zip

Appreciate your expert diagnosis.

[Donald Polidori]

Hello Chummee,

Until the devs can get on here, I thought I'd tell you what I've learned when I had this issue.

I saw in your logs that you were on the east side of the pier when you calibrated and the west side when you were guiding.  That meridian flip will cause the direction of the dec corrections to need to be reversed.  What you are seeing is as you suspected with the correction going the opposite way and making things worse.  Next time you go out, if you calibrate on the same side on which  you plan to start imaging you should see this problem go away.  But you will still need to deal with a median flip.  In the "advanced settings" under "guiding" there is a check box to reverse the guiding direction in Dec after a meridian flip.  Whether this box needs to be checked or not depends on your mount.  Because  you had the issue, I'd suggest you change it from whatever it is now, so if checked, uncheck it and vice versa.  You can also do some google research and find out if your mount automatically changes dec direction on flipping or not.  I have a Paramount MyT and I had to check the box.

--Don

[Chummee]

Don: Great to know it’s not a mechanical problem. Thanks for the excellent tip.