| Spburt |
| (journeyman) |
| 07/01/09 01:30 AM |
LX200 10 in. Classic "reverse declination" Slewing
|
Hello,
Sean here and first time post on CN. Been a lurker for a few years and depend on these forums for lots of well informed opinions and facts.
Got an issue with a recently purchased (USED) 10 in. LX200. Scope is around 10 years old or more and in like new condition with superb optics on the OTA.
The hand controller is version 3.34 if that is helpful.
So here is my issue. After trying all methods of (ALTAZ, no wedge)alignment, 1 Star level mount,1 star known location and good time and LOC entry, 2 star known and 2 star unknown location ( just to try ).
Also tried the sync method where you press star, enter, enter, select star, slew using E,W,N,S and then press ENTER when star/obj is centered in eyepiece.
Used the various recommendations from the MAPUG website. Tried it all or atleast all the recommended methods I could find from various resources.
In every case the scope slews correct in RA and DEC with one exception. It slews to the south instead of north or rather negative instead of positive. The hand controller indicates the correct coordinates in declination but if the DEC coordinate was +44 degrees it slews south and indicates +44 degrees.
So it aims south for a northern sphere object such as Deneb or Altair. Once I do the star alignment and all seems well, select any object or star it slews to the correct RA area of the sky and negative instead of positive declination, but the hand unit indicates correct coordinates.
Hope any Classic users or previous owners can help me with this.
Hope I gave enough info.
Thanks for any help.
Sean
Port Orchard, WA.
EDIT:
I have to add an additional note about this mount.
I set the scope up with the panel facing north and the OTA facing south with both axis on Zero. When I slew with N, S, E, W, keys it moves in the opposite direction. I press the North key it goes South. W and E are correct.
Now maybe I am totally off and someone will say " No Dummy "
, one of those moments. But this behaviour seems curious to me. If I am facing south and press North the scope should slew up. Right?
| chicot |
| (super member) |
| 07/01/09 05:18 AM |
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Re: LX200 10 in. Classic "reverse declination" Slewing
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Not trying to be funny but you do have the switch on the control panel set to "N" and not "S", don't you?
| Spburt |
| (journeyman) |
| 07/01/09 09:27 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Quote:
Not trying to be funny but you do have the switch on the control panel set to "N" and not "S", don't you?
Yes, I have made it a point to check and recheck that the switch the switch is in N position almost obsessively.
I wish that was the issue.
It seems so likely that that is what is causing the error that I even tried it in S just to see if the switch was somehow reversed but it made no difference.
Appreciate the thought though.
| Locoweed |
| (sage) |
| 07/01/09 09:32 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Hmm
Never tried it my self, but I would expect that with the switch in the S position there should be a difference. Maybe there is a bad connection to the switch or the switch it's self is bad?
| chicot |
| (super member) |
| 07/01/09 09:59 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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I would expect that too. Perhaps the switch is indeed faulty.
| imjeffp |
| (Aluminum Falcon) |
| 07/01/09 11:24 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Hmmm... I know you can reverse the directions in the handbox settings somewhere, but that wouldn't affect goto's.
I would try a different dec cable if I could. If the one you have has a crossed connection for some reason, it could be sending a reversed signal--maybe, I guess.
I think the N-S switch only matters in polar alignment.
| Spburt |
| (journeyman) |
| 07/01/09 11:34 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Quote:
Hmmm... I know you can reverse the directions in the handbox settings somewhere, but that wouldn't affect goto's.
I would try a different dec cable if I could. If the one you have has a crossed connection for some reason, it could be sending a reversed signal--maybe, I guess.
I think the N-S switch only matters in polar alignment.
Thanks for the input.
Wouldnt it stand to reason that when using ALTAZ mode in the southern hem rather than North that the dec motions would be opposite (in dec) when slewing to the same object.
Another stange thing is that the manual states to use a pen or some means to manipulate the N/S switch. On my panel the switch is not recessed or level with the panel, it sticks out and I can use my finger to switch it....?
| Joseph Gillman |
| (Carpal Tunnel) |
| 07/01/09 05:28 PM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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I vaguely remember it being a regular, protruding switch on the LX200 classic but my memory might be crossed with an old C8.
| chicot |
| (super member) |
| 07/02/09 05:36 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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I think that that's normal. Mine is exactly the same.
| Spburt |
| (journeyman) |
| 07/02/09 11:49 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Quote:
I think that that's normal. Mine is exactly the same.
Thanks for clearing that up. The N/S switch does'nt seem to be the problem.
I am thinking both drives on my mount are operating in reverse directions even though the encoders are tracking and updating RA and DEC coordinates properly.
Question for Chicot or anyone for that matter:
If I operate my scope in LAND, ALTAZ, or POLAR when I press the North button declination should go up and the scope should slew up, S should make declination go down and slew down, slew West and RA goes up and the scope should move west, slew East and RA goes down and slews East?
If this is the case then my mount is opposite.
| imjeffp |
| (Aluminum Falcon) |
| 07/02/09 12:23 PM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Those directions can be reversed using a setting in the telescope setup.
| Spburt |
| (journeyman) |
| 07/02/09 02:18 PM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Yes you are certainly right and I did check those settings multiple times.
| Skywatchr |
| (Carpal Tunnel) |
| 07/02/09 03:01 PM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Sounds like someone put the OTA on the forks upside-down.
Remove the finder bracket and run it with the scope upside-down and see if it all seems to be right. ;-)
Jeff
| Joad |
| (Wordsmith) |
| 07/03/09 08:54 AM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Welcome to Cloudy Nights, Spburt. I hope you resolve your LX200 "reverse slew" mystery soon. You've come to the right place for advice.
| Spburt |
| (journeyman) |
| 07/03/09 02:29 PM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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Thanks for the friendly welcome Joad, much appreciated.
Quote:
Sounds like someone put the OTA on the forks upside-down.
Jeff
SO this idea definitely worked Jeff, Bravo. It does indeed slew properly with the OTA upside down ie., focuser nob at top left, handle at the top and the finder scopes at the bottom. The scope slews properly in declination.
This also turns the fork tines around so that the RA lock and control knobs are turned away from the eyepiece position, as well as the tine handles and declination control knob.
I am relieved that there does'nt seem to be an issue with the electronics of the scope. This mechanical issue seems an easy fix but I cannot wrap my brain around getting the scope mechanically oriented properly. Help!
| Skywatchr |
| (Carpal Tunnel) |
| 07/16/09 06:53 PM |
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Re: LX200 10 in. Classic "reverse declination" Sle
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It's pretty easy. Search these forums and you'll find lots of info on how it is done. The hardest part is getting the forks aligned squarely to keep the GOTOs accurate. Mapug also has good info as well.