Quote:PhilippeYou said that you entered PDT (Pacific Daylight Time). That's the time zone for the West Coast of the United States and I don't believe that's where you are.Fred
Quote:When you stand behind the mount and look forward, do you see the vertical AL pedestal on the left or right side of the scope OTA? Here's a side view of the scope. If the vertical AL pedestal is behind the scope OTA then it would be wrong and cause errors. It should be in front as shown in the photo. From behind, it should be on the left.http://www.telescopes.com/telescopes/catadioptric-telescopes/celestronnexstar...
Meade LX200R-8 Nexstar 6SE AT80EDTA on Minitower Lots of glass, aluminum, and plastic Arctic origin - http://www.youtube.com/watch?v=wAx58lIynfY&feature=player_embedded#! Weather station - http://classic.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KFLKENNE... 73s de KF4JU
Quote: Although I'm still thinking of some mechanical fault, what is really strange to me is that behavior that, if I align on Polaris and (say) Altair, a goto Dubhe or M13 is 10-15° off (huge) on Alt only. But, going back to Altair or Polaris from Dubhe or M13 is right on. Still, if Polaris is NOT amongst the alignment stars, the above is not true - going back to alignment stars is wrong. This would not be consistent with a mechanical error that should always be here, but rather looks like some other location / timing error that I would do. But I checked that 1000's times - and again, although stupidy if still a very solid hypothesis, I have no problem with my CPC1100 or Skywatcher Dob14
Quote:Philippe,That is indeed strange behavior. Have you done a Factory Settings reset yet? You'll need to save your backlash settings and any filter limits you've changed but doing this reset will clear out all the temporary data locations. This has been proven time and time again to clear up strange behavior of the hand controller.
Truth is the cubed root of Verbosity.
Quote:It looks as if Phillipe is further North, I don't think he ever said where he was.
Phillipe, can you give your approximate location please. To the nearest degree will do and won't compromise your security.
There was talk about changing motors and/or encoders. Where did these come from and are you sure they are the right ones?
Quote:ChrisPhilippeCan you confirm the amount and direction of the error? In essence, is it always short or long on the target and is it in proportion to the angle traveled to get to the target. By that I mean, some error when the target is X degrees in error for some angular change and 2X in error for twice the angular change. Using the idea from Chris, do you see 90° of change in the AL angular readout when going from horizontal to vertical. Your mount may have the wrong gearbox in the AL assembly. This test alone will determine if the gear ratio is correct.http://www.celestron.com/astronomy/parts/nexstar-6-8-se.html
Quote:This is a really long shot but could the two motor cables be plugged into the wrong controller board? Can you confirm that the left/right slew buttons cause the mount to move only in AZ.
I've been trying to recap a little on what has been said and also to form a picture of your particular night sky and timings but first, a couple of issues from the foregoing posts which perhaps you can confirm/clarify ?
1) Balance. At one stage you state that your 8SE's OTA is fairly well balanced; maybe a little backend heavy. The statement suggests that you are looking for good balance which, in fact, should not be the case.
The 'scope's OTA should have a significant imbalance (but by no means severe), in order to put a load on the gears. Thus the OTA should be placed either to provide fore-end heaviness, (when fully loaded with all usual accessories), or rear end. Experimentation, (and I know you've already done this), should then be resumed to determine whether a Positive or Negative Alt. GoTo approach is better suited to this imbalance.
I DO APPRECIATE YOU'VE ALREADY BEEN "THERE" !
It looks as if you are currently using a Negative Altitude GoTo Approach setting. Can you confirm this just for the record ?
2) For an object to move out of the field of view of a 24mm EP in 15-30 minutes, mediocre to poor tracking is indicated. This may be attributable to poor anti-backlash settings and/or the phenomena I described in that article I wrote for CN in 2007; (see above).
Can I therefore ask you describe in some detail, how you set the anti-backlash for your 8SE ?
Now to that model of your particular sky.
I have tried to model this using Stellarium's planetarium on the current evening sky as seen from Los Angeles, (owing to the fact that I don't know where you live specifically in Ca. but on the basis that the Los Angeles sky will differ very little if at all from yours).
Thus, and correct me please if I'm totally in error, I estimate the following:
1) Viewing Window: Approximately (dusk to dawn) 8:00pm to 6:00am PDT.
2) At ca. 8:00pm Duhbe lies at ca. Alt. 19-20 degs. just west of north and reaches its lowest Alt. point (ca.6 degs. at ca. 12:30 am.(due north).
3) It then proceeds to climb in the sky reaching its highest visible point, (26 degs). at dawn around 6:00am.
If this is a reasonably accurate model with which you can agree, may I ask at what time were you making your observations when you mentioned that, when slewing to Dubhe, your OTA finished its slew, some 15-20 degs. below Dubhe. It sounds as if it was either virtually pointing to the horizon or below it considering the 15-20 degs "off" that you originally mentioned.
Also, from what you have described and if my viewing window is correct, you seem to have targetted objects which lie west of the north/south meridian line. Have you yet tried objects to the east of the line and if so, with what effect ?
Please don't take it that I'm calling into doubt anything you have stated, Philippe, I'm just trying to obtain a more complete picture of what is going on, hopefully for all of us involved here who are trying to help solve this enigma.
Given though that the angular distance between the horizontal and the vertical produces a constant 72 degrees and not the expected 90 degrees thus "undershooting" the true value, how can one explain that, while Dubhe is "undershot" in making a GoTo to it, the other stars/objects you have mentioned,(e.g.Vega, Altair, M13) are overshot"
As to the problem lying solely within the gears, one aspect might point to this if you recall the poor tracking of your 'scope which in turn, suggests excessive backlash despite the fact that you seem to have corrected for this successfully.
One other thought: Try removing the OTA and recording the angle obtained between the horizontal and the vertical. Does it still record 72 degrees instead of 90 ?
Quote:The possibilities are dwindling. Looks like firmware and wrong gearbox are all that's left. Never heard of a gearbox problem so that leaves firmware. Maybe it's got the MC code for a GEM mount with a different gear ratio.
Quote:Confirm that the HC version is 4.18. It plays well with MC5.14. Be sure you're using the MC and HC updater and not the newer one for the HC Plus hand sets.
Quote:Philippe,To help me understand ... You first bought a 6SE that did not work. The dealer replaced the mount for that first 6SE. Is this second mount the one that said "wrong firmware" or is that error message from the first mount?Your dealer should certainly be taking care of you ... you have a failure out of the box and not a warranty repair for a scope that's been in use for a while.
Quote:Don't you have consumer protection laws in Canada? Can the dealer really sell you a faulty mount and abandon you? This mount came with a two year guarantee didn't it?
Celestron will quite reasonably want the mount back so they can find out what has happened. It's difficult to see how it could be the firmware but it could be a motor that was intended for a different mount.
The other person who might be able to help is Andre Paquette http://www.astrogeeks.com/ . He used to be the Celestron developer and lives in Canada. He may be able to help about what's happening here or may be able to update something.
Quote:Can you look at the encoder specs at USDigital.com to see if the one you have is correct? The other link in my same post said the PPR is 256. It's starting look like your dealer may have repaired the second mount with the wrong parts. Also, you may have gotten the first mount back with the wrong parts. I don't think anyone on this forum has ever seen this kind of problem but you sure have our attention as to the cause and fix.