East movement after slew

[telemarker (Keith)]

My older mount - an LXD75 - has a bit of a problem. After completing a slew it will move to the east for a substantial distance before tracking commences. The same will occur after using the west button on the hand controller. This is not a simple case of backlash as the motor is turning at approx 2x sidereal during this movement.

I'm unable to calibrate PHD with a GPUSB. Is there a setting in the autostar controller that would be causing this?

[AndrewJ]

This is normally due to bad drive training results.
Ie when you finish a slew, and the scope needs to reverse direction, the scope slews at approx 2x sidereal to account for the "theoretical" backlash before reverting to normal tracking.
If you are overtrained, it will effectively slew too far whilst applying the expected lash, vs the real lash.
What are your current drive train/backlash numbers?
( not percentages, but drive train values )

Andrew

[scopemankit (Chris)]

Try and move your counterbalance to ensure slight bias in the opposite direction, so the motor is always pulling against a load.

[telemarker (Keith)]

Originally Posted by scopemankit

Try and move your counterbalance to ensure slight bias in the opposite direction, so the motor is always pulling against a load.

Thanks for the reply chris. I'm afraid its not a simple balance problem as the motor is actually driving the movement faster than the sidereal rate until it decides it has moved its sufficiently, then it starts sidereal tracking. By this time its way off target.

Originally Posted by AndrewJ

This is normally due to bad drive training results.
Ie when you finish a slew, and the scope needs to reverse direction, the scope slews at approx 2x sidereal to account for the "theoretical" backlash before reverting to normal tracking.
If you are overtrained, it will effectively slew too far whilst applying the expected lash, vs the real lash.
What are your current drive train/backlash numbers?
( not percentages, but drive train values )

Andrew

Thanks Andrew, I wasn't able to fire it up last night due to atrocious weather and the amount of water inside my shed but this sounds like a likely suspect. I had only recently replaced the handset, stripped/regreased the mount and done a warpsdrive upgrade but hadn't retrained the drives. This is now on the to do list once the weather clears and I dry my shed (I keep every thing off the floor luckily).

Thanks for the responses guys.

[acropolite (Phil)]

There have been bugs in the handbox software that cause wierd slewing effects after a manual slew or goto.

It would be well worth checking to see If there are any known issues with the software version you're running.

[telemarker (Keith)]

Thanks Phil, something to keep an eye on.

Managed to drag the mount out yesterday arvo while the rain was having a rest. Did a drive training run and it appeared to stop the movement post slews. Of course more cloud and rain stopped any hope of testing it under the stars.

[telemarker (Keith)]

Hallelujah, a cloudyless night. Andrew hit the nail on the head, so problem solved. Even got the autoguiding going through an OAG for the first time. Yay.

Thanks all.