Can I diagnose mount issues with software?

[RugbyRene (Rene)]

Hi all,

Last night I had one of those nights where nothing went right. I had mount issues (AZEQ6) where it wouldn’t align (plate solve) properly and got Dec errors during guiding calibration.

When I could get guiding working the total RMS was never below 1.5-2 and this was with proper balancing and a dialled in polar alignment.

Before I pay for a service on my mount, I wanted to see if I could diagnose the mount myself and was wondering if there’s any software out there that could run some tests and provide a report. I know PHD2 does something like this but was hoping there was something that provided a comprehensive set of test results.

Cheers

Rene

[multiweb (Marc)]

I recommend Pempro.

[Atmos (Colin)]

It’s not of any help but I’m convinced China sends their mounts out with Gremlins. Most nights my EQ6 would work fine, sometimes very good but other nights it refused to cooperate

I’m not aware of any program that does what you’re looking for but my suggestion would be to leave it for a night or two, Lee the gremlins have their fun and then it’ll go back to normal

[ChrisV (Chris)]

I think it should have been better than that last night in Sydney. Around midnight my (modified) CGEM was doing 0.6 arcsec rms, but I had a really nice guide star.

Maybe if you used PhD log viewer to put up what your guiding looked like. And maybe if you also put up the calibration. There's enough people around who could advise.

Edit: I had some bad Dec issues last month and gave up. Later noticed the puck on the mount head was loose. Extreme idiot factor

[peter_4059 (Peter)]

You can collect an unguided log from phd2 and do fft analysis in phdlog viewer. This will give you a report of tracking error frequency and amplitude. By working this out you can home in on the source of tracking errors.

[The_bluester (Paul)]

One thing to note, balancing an AZEQ6 is not as simple as it might be, due to the design of the clutches. If you balance the Dec in the way that is normally suggested it might still be out of balance.

If you balance it by rotating the RA til the counterweight shaft is horizontal and then release the Dec clutch, the clutches will stick, you need to rotate the RA until the head is counterweights high. I just re tried it with my kit (Orion Atlas, but same same) with it deliberately camera heavy, done the "Right" way it just sits there, move the RA an hour further and the camera heads for the floor.

It is just a pity there is no way to do the same thing on the RA axis.

[RugbyRene (Rene)]

Originally Posted by multiweb

I recommend Pempro.

Thanks. This looks like what I'm after but it's Windows only? I'm running my software on a RPI with INDI, not ASCOM. Is there something similar that runs on Linux?

Rene

[RugbyRene (Rene)]

Originally Posted by The_bluester

One thing to note, balancing an AZEQ6 is not as simple as it might be, due to the design of the clutches. If you balance the Dec in the way that is normally suggested it might still be out of balance.

If you balance it by rotating the RA til the counterweight shaft is horizontal and then release the Dec clutch, the clutches will stick, you need to rotate the RA until the head is counterweights high. I just re tried it with my kit (Orion Atlas, but same same) with it deliberately camera heavy, done the "Right" way it just sits there, move the RA an hour further and the camera heads for the floor.

It is just a pity there is no way to do the same thing on the RA axis.

Yeah I balanced the mount by moving RA till is was horizontal. I have noticed the clutches do stick. They don't feel all that smooth.

I'll try what you suggested.

Cheers

Rene

[RugbyRene (Rene)]

Originally Posted by ChrisV

I think it should have been better than that last night in Sydney. Around midnight my (modified) CGEM was doing 0.6 arcsec rms, but I had a really nice guide star.

Maybe if you used PhD log viewer to put up what your guiding looked like. And maybe if you also put up the calibration. There's enough people around who could advise.

Edit: I had some bad Dec issues last month and gave up. Later noticed the puck on the mount head was loose. Extreme idiot factor

Yeah I never get good guiding. Always up around an RMS of 2. Which is why I suspect there's something up with the mount.

[peter_4059 (Peter)]

Here's an example of the FFT plot for my EQ8. The X axis is period and the Y is amplitude. The peak at 200 is the worm period - ie 198 seconds for one rotation of the worm for the EQ8. The other smaller peaks are other elements of the drive system. You can use tools like the SKF bearing calculator to work out if the issue is worm bearing related or something else. In my EQ8 there is a 0.4" peak at 48.8 seconds. This is 4x the worm fundamental which probably points to Inner Race or Rolling Element defect. I've previously had a peak at 10s which turned out to be the meshing of the belt drive between the stepper and the worm. Tightening the belt tension fixed this. For comparison I've also included the pempro report for the same data.

[JA]

Hello RR,

Power Supply issues may be an issue with mount performance. Questions to ask yourself: Are you using the standard power supply? Is it functioning correctly (output voltage (and current if you are able to measure it)) whilst tracking and also slewing? Can you try an alternate power supply, perhaps borrow one to test?

Other diagnostic questions/procedures which may lead you to a solution: Are the clutches Ok? Does the problem get better or worse with payload or any of the changes suggested? Try other USB cables to guide cam. Another guide cam? etc...


Best
JA

[The_bluester (Paul)]

Originally Posted by RugbyRene

Yeah I balanced the mount by moving RA till is was horizontal. I have noticed the clutches do stick. They don't feel all that smooth.

I'll try what you suggested.

Cheers

Rene

It is part of the design, which is quite different to an EQ6. The AZEQ clutches work by pulling the axis shaft through a needle roller bearing and the clutch is a disc in between the ring gear and the body of the axis housing (Either axis). When the clutch is released the ring gear can rotate freely on the shaft/in the housing, and when you do up the clutch it essentially becomes a single part with the housing.

The upshot is that if for instance you set the RA with the counterweights straight down, the weight of your gear and the counterweights are pressing on the clutch, keeping it somewhat engaged, if you rotate the RA to a "counterweights up" position all that weight is helping to slide the Dec shaft through the bearing and disengage the clutch. The issue could probably be designed out with springs and bearings to force the clutch parts apart, but the mount would cost a lot more!