Guys I need someone with experience with both the mount and gemini.
Everything is working well and accuracy is very good but PEC is really giving me the *****.
Not long ago I was getting up to 5 minute unguided exposure...now I am lucky to get 20seconds before I get severe star trails...I have done my drift align and thats fine....all my problem's are pec related...the stars are just jumping up and down.
So easy fix you say....just train the PEC..yep so I do the PEC training.....its says pec is active....nothing changes.....my pec is terrible.....for example a bright star is moving from side to side about the width of 5 stars in less then 1 minute....so you could imaging what the stars look like in just 30seconds.
Am I doing something wrong...this is frustrating me ATM but everything else is working perfectly.
I don't know anything about the G11, only seen one in the flesh once before. I seem to remember [1ponders] saying something about a similar problem with the Mapleton G11. Maybe something's become loose inside, that would account for your initial good performance.
My GM8, I have had some problems with it's DEC. For all of the problems, I've asked the Yahoo! Losmandy group about it. I always get the same answer: Loosen off the adjustment screws enought o move the worm a little, re-seat it and tighten it up again, ie, get it back in to a snug fit.
I've found this fixes my problems sometimes and not others. Right now I have a problem where I can't remove backlash. For some reason no matter what TVC value I enter, it appears to have no effect. Strange. Again I've been given the same advice, but haven't tried it yet.
Tony I agree with Roger, however there may be another thing to look at. How did you go about training your PPEC? If you used a camera to autoguide then it might be worthwhile checking the end play in your worm blocks.
Oh and is the problem just in one axis or in both and if only one - which one? Bet it's Dec or RA only.
Also if you're autoguiding to train your PEC what guiderate are you using what camera and other equipment/programs. What star were you using/how near to the zenith, what were your seeing condition like when training? How's the balance on your scope when training and do you rebalance when putting on the camera etc?
Try this. Grab your OTA and try to rock it in RA and then in Dec. Not actually move it in Dec and RA, but just rock to see if there is any play or free movement in either axis.
A couple of things, how old is your G-11, if it is new you should have the High Precision Worm which was introduced a couple of years ago, how is your balance, it is critical with Losmandy mounts, as mentioned in a previous post, is your worm adjusted properly, I can send you articles on how to adjust it properly using feeler guages. If you feel it is definately PEC then it will either be balance or worm adjustment. You have to get the worm tight enough so it dosn't bind, you check this by moving it by hand for a full rotation, you will feel the tight spots, you have to balance the tightening with the backlash.
With your Gemini, what version are you running, there is a bug in the current Level 3, V1.13 concerning training PEC, it is well documented on the Gemini Users Group. Most users have given up trying to train PEC and are now waiting for the release of Level 4 which is now in advanced beta, the problem of PEC has, apparently been addresseed together with a number of other bugs.
If you aren't a member of the Yahoo Losmandy and Gemini Users Groups, I would join, the archives of those groups have a lot of info.
One thing I forgot to mention, if your mount is an older one, there was a problem with the grease Losmandy was using, it apparently reacted with the grease in the bearing and became a gluey mess, I pulled my GM-8 apart last year and found the bearings were sticky, cleaned them up and relubed using a Silicon based grease and they are now smooth.
I do have backlash that needs adjusting on the Dec but the RA has no slop movement or backlash it's perfect....and thats where the PEC needs adjusting...I am not getting much PEC on the dec axis.....thats fine....all this has to do with the RA axis.
I did pec training manualy but with the use of the toucam so I was visualy looking at it on the monitor instead of constinently looking through a iluminated reticle eyepiece.
Pec training was easy...I could see I needed to make large corrections on just the 1 axis but this was no problem..I had the star centered very well for the entire 4 mins.....I even did the PEC training 3 times in a row again.
The star I was using was around 10-20 degreez of the meridian.
I have balanced the mount.
Here is diagram I just made up on what is happening regarding star movement on the RA axis...this is approx 2800mm focal length with a toucam.
I get the impression by looking at the diagram on your post that the worm is moving from side to side, you say you have backlash, it looks to me like your worm is moving in the worm blocks ie side to side, this very easily adjusted, that would definately account for you star moving only in RA, also have you let the autoguider do it's own thing and see what happens, gentle reminder, make sure the Gemini is in Photo mode.
There is one other thing I can think of that might be causing the problem, take off the worm cover and have a look at the Oldham Couplers, there is a known problem of them becoming loose on the shaft and causing similar to what you are seeing, use an allen key and tighten the small grub screws, 4 of them from memory. While the cover is off, have a look at your worm and see if it is moving in the worm blocks.
OK, taking the cover off is no problem, just undo the 2 small grub screws and lift the cover off, inside you will see the worm, the Oldham Coupling is to the left ( I am running off memory here, I don't have my mount in front of me), you will see the coupler which is a white nylon thingy, either side of the coupler you will see the shaft with the metal part of the coupler, there are grub screws that hold those parts to the shaft, check that they are tight. With the worm, just rock the mount from side to side and see if it moves within the blocks you will see on either end.
PM with your email address and I will send you what I have, including articles with photographs. I have found that you have got to be prepared to play with Losmandy mounts to get the best out of them.
They are meant to take up any mis-aliagnment between the motors and the worm shaft ie if the motor is slightly off centre, it would try the bend the shaft if it was a straight through fitting, the Oldham Couple allows a slight sliipage to counter the bending effect, I think I got that correct, someone else might be able to explain it better.
![[1ponders]'s Avatar](../vbiis/customavatars/avatar45_9.gif){kind=avatar}
