Anyone who owns a PME would have heard that alarm at one stage or another. If the balance is not perfect or there is something dragging the mount stops and sounds a warning to let you know there is a problem.
This should also be borne in mind that the plungers in the plunger assembly need to be tensioned correctly. Software bisque have a PDF on this and anyone with a large scope on their PME needs to read te document.
Last night no matter what I did the mount kept stopping and sounding the alarm at intermittent times. Aside from the plunger adjustment, what other issues could be causing this? I need to check this out very thoroughly as I have the 12RC sitting on the mount now and I want to make sure I have covered all my bases. I checked all my cables externally and none were pulling.
I have checked inside the mount too to make sure no cables are pulling or getting caught. Nothing seemed at fault in there. Anyone have an image of the inside of the mount and where the cable ties are located which hold the through the mount cables of the mount itself?
Setting the plunger screw at 1/2 turn back from tight seems to have sorted the problem for now, but I am sure it will go off again in the future.
I have only had this scope on the mount once before and it worked ok, but I was not doing a pointing run or doing so many slews. Any tips from the PME owners? Have I missed something?
Seeing as you had trouble with your gearing it would seem most likely to be something to do with that adjustment. Its taken the heavier weight of the 12 inch to show it perhaps.
I haven't heard that alarm and the CDK17 is quite heavy.
I take it you are balanced and no guide scope on top?
I'd say you are on the right track. A post to PME support forum may be the go.
Make sure the balance knobs are functioning smoothly and correctly as well. Easy to do while you're in there checking the spring plungers.
That's shocking that you have to run your spring plungers only 1/2 turn backed off. That's very tight! So tight that I'd think it would cause binding. I hope you did a good job greasing the gears with Lubriplate. I have a comparatively light load (an EdgeHD 14 and stuff) and can run mine at 2-1/2 turns backed off.
Don't forget to check for binding through the mount cabling.
Oh, I think you already know all this stuff, but gosh, what else could possibly go wrong?
Seeing as you had trouble with your gearing it would seem most likely to be something to do with that adjustment. Its taken the heavier weight of the 12 inch to show it perhaps.
I haven't heard that alarm and the CDK17 is quite heavy.
I take it you are balanced and no guide scope on top?
I'd say you are on the right track. A post to PME support forum may be the go.
Greg.
The former issue was my thinking too. I figure the spring plungers were not set up properly when the mount had the new worm installed either.
Yes I am balanced and no guide scope either. Good point about the PME support forum.
Quote:
Originally Posted by frolinmod
Make sure the balance knobs are functioning smoothly and correctly as well. Easy to do while you're in there checking the spring plungers.
That's shocking that you have to run your spring plungers only 1/2 turn backed off. That's very tight! So tight that I'd think it would cause binding. I hope you did a good job greasing the gears with Lubriplate. I have a comparatively light load (an EdgeHD 14 and stuff) and can run mine at 2-1/2 turns backed off.
Don't forget to check for binding through the mount cabling.
Oh, I think you already know all this stuff, but gosh, what else could possibly go wrong?
Earnie the balance knobs are really smooth. I can back them off more but only went to 1/2 a turn back off from tight.
Yep lots of lubriplate, but it might be time for some more too.
Only place I did not check for binding in the mount was on the Dec shaft.
No problem about things going wrong. I have learnt from long experience that little problems help teach things that need to be learnt.
Quote:
Originally Posted by Peter Ward
The spring takes up the tension, and the manual recommends backing off 1/10th of a turn to prevent binding (yes, RTFM )
.... it also says 1 and a half turns will totally disengage the worm...hence not sure where that 2 and a half turn suggestion came from
I'd also be checking lubrication, and double checking balance.
Also simply turning the mount off for a hour...letting things cool...and re-homing can work wonders.
Thanks for chiming in Peter. Yeah I have RTFM a few times, but thought it was a knob tick or two.
I will check the balance again, but I am sure this is good. Mind you I went over that pretty late last night and could have missed just a fraction or two.
Maybe some more lube, though it did look alright when I had the inspection plate off last night. That said, double checking has everything to be gained.
Thanks guys for the suggestions. I'll get back to you when I find the culprit or I get stumped.
The balance knob typically needs to be backed off maybe half a turn by feel. When you have the covers over the worm blocks off in order to adjust the spring plungers, you can actually SEE rather than just feel how far to back off the balance knobs.
Ernie this is as I remember reading. I see also the confusion that I might have caused too. I was talking about the balance knob when I said I had it backed off to 1/2 a turn. I should have used the correct wording. The spring plungers do not appear to be in very far at all and may in fact be in the correct position. I will check though. Thanks for the link and exert from the PDF.
I had also forgotten about the speed settings though. I will adjust that too.
I have read elsewhere that lowering the slew speed rates can also help prevent a stall. I read that when I was looking at weight capabilities of the PME and CDK forum advised against using a PME for the CDK20 as it would stall unless slew rates were set very low.
The PME as does the PMX, standardly slews very quickly compared to other mounts I have used. So there is plenty of room to slow it down and still be good.
I had also forgotten about the speed settings though. I will adjust that too.
Oh yeah, right, speed settings. Good catch. For awhile I ran my mount at 100% speed and maximum acceleration. It sure runs like a bat outta hell with those settings. Didn't seem to affect accuracy any either. Sounds cool as all get out in operation as well, sort of like an assembly line robot. After awhile I returned to the factory default settings out of fear of possible long term consequences of which I may not be aware.
Not quite on topic but I must say I am impressed with the PMX slewing.
It races to the target and stops and doesn't seem to need to correct its position and its bang on. Impressive engineering.
One thing you have to be really careful of with the PMX - the gears will slip with moderate pressure.
Today I was merely polishing the drawtube of my scope and with only moderate pressure it skipped on the gears a little bit.
So if you take the camera off the scope to unpack you MUST lock the axis otherwise it may flip out of control and possibly wreck something.
This seems to be the downside of this new clutchless design. The gears must have some spring mechanism to engage them and they may be a tad too easy. On the positive if your mount ever did heaven forbid track into the pier then the gears would slip and no damage would be done.
One thing you have to be really careful of with the PMX - the gears will slip with moderate pressure.
Greg.
Greg,
I've heard others post that their mounts have skipped teeth when a little pressure is applied. SB posted "Adjusting the Paramount MX Cam Stop," in the download section. http://www.bisque.com/sc/media/p/55408.aspx According to the paper, "When properly adjusted, it does not allow the worm to separate from the gear." If I'm reading that correctly, it sounds like an adjustment might be in order.
Nick
I checked the spring plungers and these were ok, but one was a little further in. I have now shifted that out just a little to suit the other plunger which is correct.
The alarms still went off last night, but today I rechecked balance. I was only very slightly out of balance (I do mean slight too) and I have found that I need to be more than 1/10 turn from tight on the balance knob. It is about 1 full turn and a bit. Even then the alarm goes off. Maybe time to check electronics.
PA is now near excellent. 15 seconds on MA 25 seconds on ME, close enough for me.
Point is good too, but could do with more points. I had some trouble last night with pin point solving. Odd behaviour.
Working through this slowly, but would like some advice on the mount alarm stuff. Peter can you help please?
It seems like a very specific and possibly unusual fault.
Have you posted it on SB PME support forum? That way one of the Bisque brothers will answer.
An insect on your electronics board?? Or perhaps a sensor that has become faulty.
Greg.
Quote:
Originally Posted by Paul Haese
Just a bit of an update.
I checked the spring plungers and these were ok, but one was a little further in. I have now shifted that out just a little to suit the other plunger which is correct.
The alarms still went off last night, but today I rechecked balance. I was only very slightly out of balance (I do mean slight too) and I have found that I need to be more than 1/10 turn from tight on the balance knob. It is about 1 full turn and a bit. Even then the alarm goes off. Maybe time to check electronics.
PA is now near excellent. 15 seconds on MA 25 seconds on ME, close enough for me.
Point is good too, but could do with more points. I had some trouble last night with pin point solving. Odd behaviour.
Working through this slowly, but would like some advice on the mount alarm stuff. Peter can you help please?
Not yet Greg, but I reckon I will get it posted tonight.
No insects in there. I had a good look this morning for problems. It could be that I need to adjust the worm either to the left or right. Remember I put it dead center but that might not be optimum. I asked on the Bisque about that particular thing and got no reply. That was months ago.
I have now had a bit of a look at the data base and forum and this issue seems to crop up from time to time in various forms. Mostly related to either over tightening of the balance knob, incorrect balance or the cold being an issue. None of which in my case are relevant. I changed the scopes over last night at 1am and even the TSA is doing the same thing. Although I got it behave for several hours afterwards.
I have checked the wiring, I have regreased the entire RA (RA is the light flashing on the communications board and on the board inside the mount), and made sure nothing was too tight or out of balance.
I have posted on the forum and waiting on a reply from the Bisque boys or someone in the know there. The problem is largely intermittent as the mount can run with both scopes for long periods of time an not have the alarm sound and halt the mount.
It could be the boards, motor (not likely as it is stone cold after hours of slewing), but I am confident it is not the weight or balance. Reason being is that it did it without the worm being engaged and without any weight on the mount at all at least once last night. I will check the electric today and have checked for insect and rodent invasions and that came up with nothing.
If anyone has any ideas it would be appreciated. Having clear skies and not being able to image is a little frustrating I must say. No doubt it is a minor thing and just needs to be found.
)
