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drift problem with Meade lX90 (first generation)

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#1 Lucky09



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Posted 25 July 2012 - 03:51 AM


We suggest me to use this forum and not the beginer's forum, so i do it ...
I put my 2 last post in this message for more explanation ...

I bought this lx90 in 2003, he works correctly in alt/az, but on the equatorial wedge (meade also)after centering an object, it's moving horizontaly from righ to left or left to right (on a 12 mm meade reticle eyepiece that represents 1/4 of the horizontal line).At the top of its course (to right or to left) it stop while 20-30s, in the center also.
Tripod is leveled and wedge is leveled with the bubble on it, nothing moved while observing.
I do a "calibrate motor" and "train drive" set sideral speed and try to custom it : nothing to do !

Controler is an autostar 497with a firmware 43EG, i also tried dick's Seymour patch 43eg, it's the same thing.

i'm using rechargeable battery, i replace them regulary and i don't test with meade alimentation: it will be incredible that was the source of th problem, i tried it this night to be sure ... Each time i do replacement i run again "calibrate motor"

I also equilibrated it with meade weight, adding or removing weight doesn't make any change, i add weight (500gr) on each arm of th fork nothing else ...

I made several time alignment and each time autostart say me that pole is more than 5' Goto function runs really well but

I really don't know what is the trouble and i begins to be exasperated to spend my nights to do tests and only visuals observations.

I have some news ... I will finish to think that electronics or mechanics are out on my scope ...

This night i tried two things :

First i redo an upgrade of the autostar with seymour's patch 4.43eg V30 and choose the option of 100% of sideral speed and i hav recalibrated motors in polar home position.
No differences except that i can play with the option of th autostart to down or up the speed but not stay center on an object.
It begins to go to stay center while 30s then it goes to left and come back while 3 mn, it stays 30-40s on the center and goes to the right then come back while 5mn ... and the process continue indefintly.

Secondly i placed the meade external power supply, no differences, it's not my cells that are the cause of the problem !

I noticed another things, unlike gspedia when i press when i press "mode" RA et DEC value doesn't change. Secondly i notced after one hour that when i would up a star with the up arrow, the star was downing while 5 min before star moving up : buttons function was inversed ...

It's very strange ...

Tomorrow i will try again the meade 43eg rom but i have not much hope ... and i will test to remove all weight.

Good night !

Thanks ...

#2 Lucky09



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Posted 25 July 2012 - 05:38 PM

Good morning ....

I follow my peripeties ...
This night i removed weight under tube and i always have drifting right to left but it's more slowly now.
So yesterday i wrote that ra and dec indicator ont the handbox does'nt change, this night after shaken it it's running ...
I do test to east to south and to west to verify, in all direction same things going to right then to left ! But at one moment, when i gone east to west i heard a "klonk" and i don't know where it come from and when i parked the scope i found a friction with the fork when i downed the tube ...

In my opinion i must have several problems ...

Question : is-it possible that a defective cable (handbox to scope) leads this drifting and secondly it is possible that tube after a long time move right to left (or left to right) in the fork. Unles it is a problem with RA motor ??

Thank you for your answer and your patience !!!

#3 Lucky09



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Posted 26 July 2012 - 03:00 PM

Hello !!

I answer to myself ... and follow the story !

Today i saw that tube is maintained in the fork by two screw, one in each fork. The right screw coul be screwed or unscrewed manually, but the left screw doesn't need to be touch. This one was unscrew i don't know what ...so i tried to screw it and tonight i found that drift was less important than yersteday.
Clouds arrived and storms are not far : i returned scope to house for protect it in case ... While this operation i shake the entire scope (wedge, forks and tube) and it seemed that tube move into fork with DEC screw and ALT screw screwed ...

I'm not mechanician, but i thinks that my problems comes from mechanics and i won't be surprised if the problems comes from the position of tube into fork, but i don't know how to adjust that .... If somebody can explain me !!!

Good night !!!

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