Cliff Hipsher ICC USN (Ret.) '03 883 XLH Meade 2080/LXD75 (Big Blue) Meade DSI Color Meade DSI Pro TEC Cooled Celestron Neximage Celestron Radial Guider Star Guider Filter Wheel Vixen Flip Mirror Some Eyepieces Swift 7x50's Empty Wallet I.A.M.B.K. I ride. There fore I am...
Quote:Scope Model set to 4504 (Dick Seymours patch 43gg28 for GEM mounts)
Az/RA ratio set to 2.19022 for 96 tooth worm set
Alt/Dec ratio set to 2.28148 for 100 tooth worm set
Quote:First this is we need to know which brand and model of GEM you have.
Third, GoTo accuracy and Polar alignment have NOTHING IN COMMON. With the exception of a One Star Alignment, all Autostar does is generate an electronic "map" of the local sky.
Fourth, using you ZIP code is not accurate enough.
Quote:It certainly sounds like a ratio problem.
The ratios also take into account the drive/transfer gearing as well.
A simple test if you have it right ( magnitude wise )
is to point your scope at a landmark ( with DEC = 0 )
( like you would for drive training )
PressnHold mode to bring up the RA/DEC display.
Note the RA.
Now slew 360deg in RA using the Hbx till you get back to the landmark.
Try not to reverse, just slow down before you get there.
Once realigned, does the Hbx Read the same RA??
Now repeat for DEC.
If the numbers arent real close before and after,
the problem is in the encoders or ratios,
either misreading or wrong.
Andrew Johansen Melbourne Australia
PS as this topic is very specific,
can i also suggest you visit the Roboscope site
as that is a site dedicated to this sort of retrofitting
Quote: The drives are direct coupled, DS shaft to worm grear shaft so I think the tooth number itself should be what I use for my retios.
Quote:Oz (is that what you go by?)
Quote:Even though I am in "terrestrial" mode the Az number slowly increments even though the motor is not moving
Quote: P.S. ... Go Webber
Quote:How do you know the motor isnt moving????
Its not something you can normally "see"
unless the motor encoder is exposed.
Quote: The manual says it is with the OTA level and pointing North. (This would have the counterwieght shaft horizontal.)
LX850 blog: www.LX-850.com
personal website: www.wadsworthobservatory.com
Quote:That's correct for the LXD650/750, but those used a different controller. I've never seen an Autostar GEM rig that didn't use the position you are using. What model manual are you using?
Quote: When I did the "pressnhold" per your instructions it displayed RA and dec even thought I has set it to Alt/Az mode.....But by pressing the down arrow I now see the Alt and Az display! Yea!
Quote:The RA dec display I had been using is clearly some kind of running clock that also changes with motor rotation
Quote: I will try to reverse the sign of dec as soon as I can get a clear night. Fully overcast tonight.
Quote:Now go to yr mount ( it can be set up anywhere and pointing anywhere )
Quote:Except the bearings that hold my motorized head at the angle of my latitude (note the large shaft protruding to the right in my photo) are permanently mounted outside.
Dave in West Michigan Tasco 10te (1959) 76.2x1200mm Tasco 7TE-5 60x1000mm f16.7 Meade 2045 sct Meade 312 80mmx900 (Japan) Polarex 114 60x900 Jason 313 SYW Yamamoto 60x900mm Orion 10 Inteliscope Dob, Nexstar C6, 102, and 80GT, Ultima C8, Coulter 8 dob, Meade ETX80, LXD75 Pentax 12x42 DCF, 16x50 PCF, Swift 8x40 Pentax ist DSLR, Canon sx110
Quote:All i'm pointing out is that for this level of diagnostic work,
you dont need a clear sky, or even the ability to see stars.
We are only trying to test if changing the DEC ratio sign
gets you into the ballpark.
Faking the time, to put a known target in a known position
makes it easy to see how close it is getting.
Quote: (Why didn't I test both axes?)
Quote: EDIT: of course there is that pesky problem of the sidereal tracking rate being off a little. I might have to break open the head and recount the gear teeth. Ugh! Means complete dismantling!
Quote:Here's a new question for you... I took great care to get my RA and dec axis to be 90 degrees apart. But I didn't do the same for the OTA vs the dec axis. To my way of thinking, since the tube doesn't spin on it's own axis (is not controlled by the Autostar), that axis (it's line of sight) is not required to be at exactly 90 degrees from the dec axis for the Autostar's positional calculations to work. Correct?