I have both a teflon bearing DS2000 mount and a roller bearing DS2000 mount
for a 2090AT telescope (the Teflon bearing mount is one with fried electronics I
purchased very cheap for spare parts). Other than the azimuth axis thrust
bearing, I can see no difference between the two mounts. The electronic circuit
boards appear identical.

On several occasions, I've had my cell phone with me but have never noticed any
correlation with its use and mount performance. I'm not saying that there is
none but just that I have never observed any.

The symptoms you describe are similar to what I experienced with my roller
bearing mount. The mount, when new, was very accurate but then started operating
in an erratic manor, e.g., occasionally my mount's movement was sort of jerky
resulting in an overshoot. The problem slowly got worse and eventually made the
mount's performance too uncertain to be usable.

I opened up the mount and found a 1.5 to 2 cm long metal shaving wedged in the
thrust bearing along with a countless number of smaller metal particles. I
cleaned the bearing and re-assembled it but the mount is not now as accurate as
it was when it was new.

The problem is tightening the azimuth axis bolt properly. Apparently there is a
narrow range of torque on the mounting bolt that will properly engage the gears
but not constrict movement. Too loose and lag time between motor signal and
movement is too long or, in the worse case, the mount can even wobble. Too
tight, and motor movement is restricted or locked in place. Through a tedious
iterative trial and error process, I am slowly improving my mount's accuracy and
have now got it to where an object is nearly always in view with a 40 mm
eyepiece and frequently in view of a 25mm eyepiece. Before the malfunction, an
object was nearly always within view of a 25 mm eyepiece.

From this experience, I would strongly recommend not to open up a newer roller
bearing mount unless there is a very good reason to do so. If you can live with
your mount in its current state, do so.

Good luck on finding your problem.

Joe





--- In MeadeDS@yahoogroups.com, Jerry <crazyj1251@...> wrote:
>
> This sounds like a dirty or loose encoder. There is also the possibility that
the batteries are low. While the electronics in Meade scopes are not shielded in
any special way I don't think that most cellphones would have an effect. Maybe a
very powerful one with a low frequency or if you are operating the scope under a
tower, but not usually.
> Jerry in Arizona
>
> --- On Fri, 4/17/09, Franciszek Cesarski <tincanandstring@...> wrote:
>
> From: Franciszek Cesarski <tincanandstring@...>
> Subject: [MeadeDS] Cellphone interference to late model DS-2090?
> To: MeadeDS@yahoogroups.com
> Date: Friday, April 17, 2009, 8:36 PM
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> There has been a comment on another group that cellphones can cause random
slewing on certain go-to scopes.
>
> I have a DS-2090 made in 2008, the roller bearing later model, which slews
sometimes with random errors in azimuth. The errors can be from about 5 to about
15 degrees beyond the proper stopping point.
>
> When the random errors occur, if I manually reset the azimuth to center the
target in question (by moving the scope against the clutch, not using the
handset buttons) the scope resumes normal operation, including accurate
subsequent slews, until the next error which may be 5 minutes or an hour later.
>
> I always have a cellphone in my pocket when I observe, a habit I picked up
from using older ETX and DS models, to set the time accurately.
>
> Has someone else seen this problem and fixed it by leaving the cellphone in
the house?
>
> My older DS-2102 does not exhibit this behavior, it is the teflon bearing
model.
>
> Thanks,
>
> Frank
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