Electrical interference in images

[neilallison]

Hey guys

I have a very frustrating problem which has manifested itself during the last couple of outings with my scope - electrical interference in the images.
I think I've narrowed it down to interference from the motors in the mount (or one of them at least).
I have a SkyWatcher NEQ6 Pro and whenever the scope is parked and the motors are not tracking, the images are fine. As soon as I slew to an object and take an image, the interference lines are there. Park the scope up again and the images are fine again :(

Has anybody else encountered this?

I am looking to replace the motors to see if that fixes the issue. I can't find where to get the motors from though. Any ideas?

Thanks and Best Regards
Neil

[pluto]

What type of camera is it?
I've never had this issue with any of my cameras on my EQ6.

[neilallison]

It's an Orion Deep Space Imager Pro II Single shot colour.
I'm pretty sure it's not the camera as I only get interference when the motors are tracking. When it's parked and the motors aren't running, it's perfect.

[pluto]

Weird!

Do you have access to another camera you could use near the mount just to see if it's affected too?

Could you post an example image to show the interference pattern?

Does the pattern change when you slew the mount at different speeds?


A bit of Googling found this thread on EQ6 steppers:
http://www.astronomyforum.net/telescope-mounts-forum/95029-stepper-motor-replacement-parts-eq5-heq5-eq6-pro-atlas-sirius-telescope-mounts.html

[neilallison]

It doesn't affect the guide camera (Orion Starshoot autoguider). I don't have another imaging camera I can use.
The interference isn't when it's slewing, it's after it's slewed to an objecxt and is tracking.
See attached images. You won't see any stars in the images as I took these this afternoon with the scope set up in my study. It shows the interference very clearly though :(

[ZeroID]

Cable RF interference ? Have you tried shielding or replacing the camera cable ?
DC lead to mount to close to cable ?
You could also try ensuring the mount is earthed.

[neilallison]

I have tried another camera USB cable. Same effect.
This is something that has only recently started happening.

I am going to disconnect every cable possible and if the problem disappears, then I will start to add things back in one by one.

[graham.hobart]

I had similar with a GSTAR EX video camera and it was RF interference from the power lead onto the USB cable. Isolating the two types of cables away from each other helped my issue.
It was a pain though because you want all the cables to run together to help with cable snagging.
Hope you find the culprit.
Graham

[neilallison]

Yeah I've had all the cables running together for a long while now with no issues :(

[Garbz]

Motors create all sorts of nasty noise, replacement motors really shouldn't have that much of an effect in that regard. In any case it's unlikely to be the motors and more likely to be the controller board drawing down loads of current every time the motor makes a step. The trick is stopping the noise affecting other devices.

One thing to check would be the performance of your 12V powersupply itself. Try running the thing of a brand new 12V battery and see if you still have issues. Poor output regulation of powersupplies can cause other loads which suddenly draw current (like steppers) to create voltage dips for all the other devices to enjoy.

If the noise is high frequency then ferrite beads which clip on to the power lead like this http://forum.flitetest.com/attachment.php?attachmentid=8262&d=1361046410 may be the answer. Not sure about your mount but the 12V power cable for my mount and the power cable for my battery both came with those clip on beads already.

Then there's a possibility that the camera itself has had a regulator fail which is passing voltage to the output. Not much you can do about that one other than send it back unfortunately. Know anyone with an EQ6 you can try the camera on?

[alpal]

3 tests I can think of:

(1) I would try using a separate new battery just for the EQ6 mount
so that there are no earth loops or current drops.

(2) I would also not use a mobile phone near the mount.
Try making a call near the mount & see if it interferes while downloading the picture.

(3) You could also try a different camera cable.


Remember - you can test all this inside your own house before your next imaging session.

[neilallison]

Hey guys.

I've tried several power sources. The power source out in the field is normally 2 x deep cycle batteries in parallel. However, I've also tried 2 different power packs as well. No change.
As far as the mobile phone is concerned, I never make calls when I'm out in the field. I'm with Vodafone so the opportunity to make a call would be nice sometimes !!!
I've tried several different USB cables using different ports on the HiTecAstro hub. The interference stays with the imaging camera.

I've already fitted ferrite beads to all the cables (power and USB).

My latest tests today included unplugging all the un-necessary devices (focuser, heaters, rear fan etc) and just leaving the mount and camera plugged in. I also separated the cables from each other. The interference was still there.

In desperation, I removed the cover from the control board on the mount and unplugged the RA motor then powered the mount on and slewed to an object.. Guess what..... No interference. So I plugged the RA motor back in and unplugged the DEC motor. Interference back again.

This has led me to believe that the issue is with the RA motor. I'm now trying to figure out where to get a motor from :(

[Poita]

From memory the motors are a cheap clone of this motor
http://au.mouser.com/ProductDetail/Applied-Motion/HT17-073/?qs=IDj0/mHVFfYwrk4WOKk7Gg==

Though I would get that verified before dropping the $$

[stevous67]

Hope you can work it out Neil, sounds like you may be close to the solution. Good luck.

Steve

[neilallison]

Bugger :(

Replaced the RA motor. Interference is still there. I had a closer look at the board though and one of the capacitors seems to be bulging on top and also appears to have a hairline crack on top too whereas the rest of them are flat. I've never seen one like that before so I'm guessing it has developed a fault.
A quick trip to JayCar tomorrow and I still might make it out in the field this weekend !!

Incidentally, I got one of the hi-torque motors from AusXMods (http://www.ausxmods.com.au) for the princely sum of $20 so not too worried about replacing a perfectly good motor. The new one sounds so much better too so I might replace the DEC one too !!

Watch this space !!!!!

[alpal]

That's good - replace all the caps.

[neilallison]

Ok. I'm officially out of ideas now.
Replaced the capacitor and the interference is still there albeit not as bad.

I probably need to try a completely different board on the mount.
If anybody has an NEQ6 Pro which is not in use that I can borrow the control board from for a couple of hours, please raise your hand :(

[neilallison]

The problem has been found :)

The control board is buggered. I swapped it out for another one with a fellow member of the ASV and the interference was gone. Many thanks Paul Litchen for your assistance.

Now I just need to source a replacement board now.

[neilallison]

The problem was not the control board - it was the camera.

However, it's all fixed !!

I contacted Orion who told me it couldn't be fixed (even without looking at it !!!).
They wouldn't supply me with a wiring diagram nor would they tell me who the manufacturer was so I could maybe get a wiring diagram from them.
Orion were less than helpful. Probably in the hope I'd buy a new camera from them. When I get another camera (or any other equipment for that matter), I will make sure that it's not Orion. Their customer service is disgusting.

Anyhoo, I digress.
I took the camera apart and found that one of the chips looked a little cooked. So I posted a message on the Orion DSI Yahoo group in the hope that somebody could tell me what type of chip it was and I got a result.
I managed to find one on eBay (US$20) and Theo from Gama Electronics (http://www.gamaelectronics.com.au) fitted it for me last night. The camera is now as good as new again (despite not being fixable according to Orion).

Theo, you are a legend. Love our work.