Joerg Schmiedmayer wrote:
>
> I had lately trouble with the drive of my 10" LX50.
> Since about 1 week it does not track the stars correctly. It moves at
> about twice the regular tracking speed.
>
> I therefor checked the drive with the following result.
>
> · The motor drive runs very uneven. The motor changes it's speed by nearly
> a factor of 4 within a few seconds???
>
> · The pulses from the photodiode (which are used to regulate the speed of
> the motor using a feedback loop??) have only about 1 V peak to peak and sit
> on a average level of nearly 1.5 volts, as measured with an oscilloscope.
> Is that correct, or should the contrast of the signal be better.
>
> · When using the 2x speed buttons the drive runs a little bit smoother.
> For the higher speeds the motion is even more smooth, but never completely.
>
> What other tests can I do. Are there any things I can adjust. Does
> anybody have a description of the electric circuit so that I can test it
> and repair it if necessary.
>
> Thank you
>
> Jörg Schmiemdayer

Jorg, this is a stretch, but maybe you increased the LX50's default
sidereal rate. It can be increased or decreased in 5% increments via
accesing the special function menu. That shouldn't make it go in spurts
though. Have you taken the bottom plate off of the scope and looked at
the worm gear to seen if it's meshing well with the RA gears? Is there a
lack of grease? If you look, DO NOT try tightening the screws which hold
the spring loaded worm/motor assembly against the RA gears! They may
look loose, but trust me, they strip easily (aluminum). If all else
for it if you need it.

Take care,
Rick Keil

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