After a `blue' filter was installed in the autoguider TV filter wheel, we have been experiencing problems with positioning the wheel which could usually be fixed by requesting the filter again. Recently the problem deteriorated to such an extent it could take half an hour of trying before getting the desired (or any) filter. Looking at the actions of the wheel while been commanded to move it became clear the problem didn't lie with the actual wheel but probably with the controller. Using an almost identical controller designated for a fiber view which never got installed and exchanging the memory chips between the units, the spare one worked and the TV filter wheel was restored to its normal operation. The spare now in use is of the same age and running time, 21 years powered on, but it has remained passive for all that time. New controllers have already been purchased and once they are programmed will replace the old unit now in place.
The focussing of the autoguider camera has now been made automatic such that it will be set to the expected value based on the telescope focus every time a telescope pointing is made. This should make things faster/easier, especially for the non-experienced observers (basically to avoid them making any big mistakes), while people can then still change the TV focus value to whatever value they want after arriving at a target.
Thomas Augusteijn 2009-05-14