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USB/Power concerns


Corpze

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Hi, i am having some strange behavior regarding USB and/or power.

 

First of all, i am having trouble with the DEC axis freezing during balancing and PID tuning, i have tried different Usb cables, active/regular cables, gold plated, both with and without USB-hub, same behavior envy time, so i wan´t to exclude the cable-issue.

-the worst case is when i am slewing at high speed in the dec-axis and having i freeze-up during the slew - it keeps slewing until Autoslew starts responding again, with near-crash experience, luckily, i am at the observatory and can stop the mount manually (holding the axis, stopping the camera/fw crashing in the pier) - I don´t know how good this is for the mount (can it cause hardware faults?) 

 

The second issue i am having (might be the cause to the freezes?) is that i am having is following;

I have connected the 12v power cable to the mount via a power-distribution box witch also the galv cable is connected to, this box is also connected to a voltage meter so i can see what voltage the power supply is distributing.

When i shut down the power to the mount, i can still read the voltage, witch is about 2.7 volts. The Usb cables are connected to the computer (the COM-cable directly to one of my computers USB ports and the mounts HUB-cable connected directly to another port on my computer, no hubs.

- Am i seeing the voltage of the connected USB- accessories? 

Is this normal?

Is there any current leaks?

 

The power cable to the mount is connected to the power box with the brown wire to 12v+ and the black to neg-

The galv cable is connected to the power box with brown and grey to 12v+ and the yellow/green and black to neg-

-should the green/yellow cable also be grounded to the pier?

 

I have uploaded a clip of the DEC axis freezing while balancing on youtube - 30sec in to the clip, you can see the freeze.

 

 

/Daniel

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I can't comment on the power supply part of your question but, in my experience, USB problems are caused either by poor cables (which you have discounted) or by software conflicts.

 

Have you changed any usb or virtual serial drivers recently?

 

Have you installed another usb device recently (or changed the drivers for any existing USB device)?

 

Was everything OK before you made the power supply changes? If so, does the problem go away if you revert to the standard power supplies?

 

Have you tried unplugging all other USB devices, just testing with the mount itself? Does that work?

 

Basically it is a matter of going back to the simplest possible configuration that works, then adding one component at a time until it stops working. This should identify the problem component.

 

Nigel

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I run a laptop (HP elitebook) via an adapter... Might try that anyway.

I have just tried what Nigel said, unplug everything, flush the comports in regedit, uninstalled old software and drivers, reboot and begun with only the mount.

I had a minor glitch when checking the balance, how ever, this could be a software hickup as well, the mount run back and forth for 10min with just that hickup.

Next up, PId under a good twenty minutes, running very well, nice curves and i started to add the fw, worked good and changed filters during PID as normal, next up, camera, as good as the fw.

Next to try is the USB_Focuser that i have huge problems with earlier this year... Will report back.

 

What i did changed was an Active, 7m long deltaco prime usb cable, to an regular 2m, that might be the problem as well (although the deltaco cable is brand new)

 

/Daniel

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USB cables over 5m always present problems. They loose information due to interference.

That may very well be the problem. Use them as short as possible. Repeaters sometimes work but not allways.

I use an Icron USB Ranger for long distances. Expensive but no problems with distances up to 100 meters... Ideal!

With a glasfibre connection you can even go till 500 meters. http://www.icron.com

 

Waldemar

Edited by Waldemar
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Well, i think a 5m cable is enough, so i will try that first, it looks like it was the cables after all, i have now completed a 40 star auto point grid with 40/40 succeeded plate solves, the polar error is now 4,5 arc minutes x 2,7 arc minutes, that will do for further tests.

I am how ever seeing very strange behavior when pointing north... already after 5sec exposure @ 700mm i see very long star trails, but in the south, i can´t see any trailing at all, and the pointing seems to be very off, even after a 40 star successful plate solve... I am using CdC, is there perhaps any other settings i am missing? J2000 etc.?

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Hi, Nice to hear you make progress.
I noticed the currency is a bit high for the DEC axis nearly 2A, I have about 1A, this is probably equipment dependent so it is probably normal. I helped a DDM60 user who had forgot to loosen the DEX axis lock screw, so double check it is not too tight.

 

About the USB cable length I have had the revers experience, I first run with a USB Ranger (fiber) and got sometime connection problems, switch then to 10m Deltaco cables, for the 2 mount connections, and the problems went away. The rest om my USB devices run through the USB Ranger.

/Christer

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Well, i assume it's all about eliminating things that can cause problems :)

 

I decided to do a second run with auto point, this time with auto slew reseted before syncing one star, and then go for a 40 star auto point.

When checking the pointing to several stars and bright messier objects, i got communication errors with the camera during download as well, so i threw away the second active deltaco usb-cable and run a standard 2m cable to the mount hub. Will test this more during the night! 

 

I double checked the clutches and they where both loosened up, what is normal power consumption with a DDM85? i cary such a small load that i had to mill down the 4,5kg weight to 2-ish kg... a 102mm APO with camera and fw is mounted at this point.

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Ok, the slewing/dec axis freeze problem seems to have been solved with the standard USB-cable, so far so good.
I accidentally made a 96 star sky model, it took a 40-ish minutes to complete but it was a good run, it achieved it without any problem at all, even the pictures pointing north was good, no trailing visible.

This plate solve didn't go well though, not a single picture solved

- Do i need to sync to a couple more stars before i begin with the auto point? Was the offset to high?

 

/Daniel

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I think you may be making pointing models with two many stars. Because you are still getting to know your mount and ironing out difficulties, it may be better to stick to small pointing models to begin with. If you spend some time getting polar alignment very good, then pointing models are much easier. Try 5 stars in each hemisphere to begin with.

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I also did a visual plate solve, got this log:
 

356 image stars found.
 (doing spiral search...)
 694 catalog stars found.
 The time limit for plate solving has expired.
 686 catalog stars found.
 The time limit for plate solving has expired.
 665 catalog stars found.
 Failed to solve plate, possibly due to input plate scale being too far off.
 
And these are the epoch settings for Autoslew and Cdc, these are right huh?
 
Skärmavbild 2015-09-27 kl. 10.19.51.png
 
Skärmavbild 2015-09-27 kl. 10.17.25.png
 
/Daniel
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Well, the first plate solve i did, with 40 stars, solved nice and fast (5minutes perhaps) , but that auto point was made with a manual four-star align before the auto point.

When i then applied that 40 star auto point, made the mistake to clear that initial four-star align, and then calculated the 40 star auto point.

 

I believe that might was the cause that my pointing was way off (5-ish degrees), hence my question of the epoch settings.
So i decided to do a completely new align, i Cleared all pointing settings in Autoslew, made a manual 1-star align in Autoslew, and then continued in sequence with the (way too big grid) 96 star auto point.

The auto point routine with all slews, obstacle limits and image acquisition with Maxim Dl 5 pro went very good.

But the plate solve was not, way too off i presume (see above log file)

 

- I think I need to do a larger initial align (4-5 star) before the auto point and then apply the new auto point on top of the initial align 

 

/Daniel

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Are you in a fixed observatory? I am not sure what you mean by ' a larger initial align'.

When I last set my system up (in a fixed observatory) I spent a long time getting the polar alignment very precise.

This was by using the approved 3 star in one hemisphere method.

When I had the polar alignment better than 1 arc minute I was able to slew to any star (without a pointing model) and it would be quite close to  the centre of the image.

Stars in the other hemisphere were a bit further from centre, but still on the image.

 

Then I checked Sequence to make sure I had the arcsec per pixel correct and the other parameters.

Then clear old configuration and run the autopoint.

 

George

Edited by GeorgeCarey
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Yes, the observatory is fixed, and according to the first align i did (4 stars) i am 0.9 x1.2 arc minutes polar aligned.

 

Well, according to the manual, you should do a manual align in Autoslew before making a auto point in Sequence? at least i have reading something regarding that, or should the auto point be able to align even with no star aligned or synched?

 

The settings in sequence is the same as when i did the 40-star auto point that pinpoint did solve.

 

As I understand, the mount should be pointing fairly good before making a auto point, the images is getting the mounts pointing coordinate in its fits header, which pinpoint is reading, and if that image is more than half a plate from the coordinates, it fails?

 

/Daniel

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The sequence I follow is:

 

Polar alignment:

 

Clear configuration

Start a 3 star model, one hemisphere only

Find the first star by hand. When it is found sync on it with CDC.

This tells Autoslew where you are pointing.

Start the new pointing model

Autoslew may ask about syncing the first star - I have done it already so just re centre the star perfectly.

Move to and re centre another 2 stars with approximately the same Dec.

Stop the pointing file and then calculate the polar error.

Centre a star due South with Dec about the same as my latitude (this is for a ddm60.)

Let Autoslew move the star away, and then re centre it with the mount adjustment screws.

Repeat this process until polar alignment is good.

 

Now the larger pointing model using Sequence:

 

Set up the parameters in Sequence.

Clear all old configurations.

Move to a star due south about 40 degrees above horizon.

Centre it and sync on it using CDC.

Tell Sequence to create the auto pointing file.

 

That is about it. If I have omitted an important step I hope someone will correct this.

Edited by GeorgeCarey
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