shreddng after I turn off the guiding, the oscillation cannot be stopped. I could visually see the star bouncing in the guide camera.
If you turn max pulse duration to zero instead of turning guiding off completely (or to 1 ms in the ASIAIR, since it is too dumb to allow zero actual corrections), do you still see the large blue guide pulses in the guide graph? If so, PHD2 is still guiding.
If no guide pulses are showing, and your stars are still bouncing around, you have a firmware bug in your mount.
This should narrow down where the error is originating from.
By the way, I do notice that the RA pulses (blue) are maxed out into a constant comb when your RA graph oscillates. So, someone is at least issuing those pulses. At other times, the pulses have much smaller amplitudes.
It is also possible that those pulses are actually correct. I.e., PHD2 is not really the one that causes the oscillation, but the mount started oscillating for some other reason, and PHD2 is responding to the star movements. Do you have a tall pillar that is not stiff enough to hold the payload? Or the tripod is standing on a wooden deck? Check all bolts (including the alt-az adjustment bolts) and tripod leg locks to make sure everything is secure.
However, all those oscillations will eventually die off (unless it is a cheap carbon fiber tripod ) -- if the oscillation remains after 10 seconds, the mount's firmware is probably responsible for the oscillations -- are you still within the return window?
Chen
