Quote:
Originally Posted by PRejto
Paul,
This is really intriguing. I only had a TEC140 on my PMX so you are a lot heavier. However, I never saw the oscillating issue both you and Greg have seen. Hopefully Greg's unbalanced idea will work though it does go counter to SB's advice with these mounts.
Have you tried unguided + Protrack as a diagnostic? It would seem that you ought to be able to go at least 5 min or so if you have a good model and accurate PA, though I guess this also depends on your FL...But, surely a few minutes. If not then perhaps something else is wrong, like PE not sufficiently corrected. Have you measured it recently? What does a guiding log look like if not making any guiding corrections? Is it wavy? Ray's idea makes sense because I doubt that a quickly changing PE could be corrected with .2 max moves + 10 sec guide exposures. But, .5 sec exposures or so probably would keep up with PE.
Anyway, just a few random thoughts.
Peter
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Peter, I have not tried unguided seriously. There have been a couple of times the clouds have got in the way and upon reacquisition the star has been close to the line if the last corrections was to bring it back to the centre line.
PE only done a couple of months ago and this problem was around long before that. It proved helpful to reducing the problem. See my comments below about Greg's suggestion.
Quote:
Originally Posted by gregbradley
What may be happening here Peter is the too balanced and not loaded to the east if there is a bit of looseness in the gears causes the autoguider to correct one way then correct back the other way. Like the guider is correcting the corrections.
That would make sense why constricting the guiding down with min/max works. Only some of the corrections are getting through with a max move of .2. So if the mount wanted to do a 1.0 correction its only letting a .2 correction or perhaps none at all (not sure if it lets up .2 through or rejects anything over .2 completely). So the oscillations then are more muted.
A loose popped up cam pin I think can increase gear looseness.
Greg.
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There might be a possibility that the worm gear is not seated properly. When the gear is engaged it seems well locked off but there seems to be the tiniest of movements. However, that might just be the depth of the worm in gear not being quite right. When I changed the worm gear I thought I had everything seated well but it might just be a very small fraction out of place. I will check this just to make sure. It's a remote possibility but worth checking anyway.
It could also be the cam pin and I will check this at the same time.
The belt I think is the correct tension but it will be checked at the same time.
There is one other possibility and that might be the PMX cannot support the load and it might be time to change over the PME to the dome and put the PMX into the roll off roof so that is carrying the FSQ only. I would not have thought this would be a problem but it might part of the issue. It is a drastic step to undertake.
In any event I will need to eliminate all possible contingencies and whatever remains will be the likely cause. Another bug hunt.
