nakbrooks

I've posted details of my solution for balancing the filter wheel in the tips and tricks section.

Interesting Dave. If my oscillations return I'll try that.

Ingenious solution George. My main OTA is heavy (70kg including imaging equipment) so I get fore and aft balance by moving the secondary OTA in its rings. As the secondary is light by comparison this gives me fine enough adjustment. My OTA is a classical cass so everything else hangs off the back end, not the side (in many respects easier to balance). My main issue is balancing the camera/filter assembly. Because I have a rotator, and because the heavy filter wheel is offset to one side of the camera, the balance changes as I rotate, even if the RA and DE axes stay put. Essentially I have to balance the camera/filter assembly independently of the rest of the equipment. The Proline has 4 bolt holes at each corner, only two of which are used to secure the filter wheel. The vacant pair are on the opposite side to the filter wheel. My plan is to have a strip of steel machined to bolt onto the camera using those bolt holes and threaded at the side with holes at 2cm intervals or so (to give me fore and aft adjustment), into which I can screw counterweights salvaged from my old Meade LX90. If this works I'll post photos. It will take a while though as I can't get the machining done locally to here. I'm also waiting for a further counterweight to arrive from ASA - at present I have a roll of spanners strapped around the counterweight arm as a temporary fix - doesn't look very elegant but it works! Nigel

Phillip Is there any way I can tell which USB is causing the ACC Device Error problem? There are 4 possibilities: 1. Cable from PC to mount Data socket on RA axis (this is a 3m Lindy USB2 cable - the ASA-supplied one was a bit too short). 2. Cable from PC to mount Hub socket on RA axis (also 3m Lindy). 3. Internal mount cabling connecting RA Hub socket and DE hub. 4. Cable from DE hub to socket on side of OTA for the SM2A controller (uses the ASA-supplied spiral cable). Obviously I can experiment with switching cables but as the problem is intermittent it would be good to know for sure which cable/socket is at fault. Both the Data and Hub RA sockets are connected directly to the PC - the only external hub is the ASA one built into the DE axis. Thanks Nigel

Thanks Phillip. Now that I have better balance and have retuned the oscillations have gone away. Nigel

Sorry Phillip - keep calling you Paul! I apologise. Nigel

Paul I think I have found the culprit - it is the FLI filter-wheel, which is heavy and off-centre. I am balanced in some orientations but not others. I used the rotator to maintain the filter-wheel's centre of gravity in the same position relative to the Axes while testing balance in numerous orientations. The maximum out-of-balance was 1 amp in each axis (most of the time it was less than 0.5 amps). I presume 1 amp is manageable? I will need to find a way of counter-weighting the filter wheel. As I have a rotator I will need to attach the counter-weights to the filter wheel itself, or the camera - I'll have to work out how to do that (they are a bit expensive to be drilling holes in !!). Regarding the readInt16 error, I am getting frequent, and apparently random, Device Error messages in ACC. These can usually be reset by clicking the message but recur every few minutes. Are these related to the readInt16 error? Are there any diagnostics I can run to find the cause of the Device Errors? Many thanks Nigel

Thanks Paul. A lot for me to chew over there. I agree it might be a balance issue. I'll try in different positions and see what I can do. Regarding USB, the camera USB is connected (to the DDM85 DE hub) but the camera power cable is disconnected (I wanted to discount trailing cables as a possible factor). Let me recheck balance and if there is still a problem we can maybe do a remote session. Thanks Nigel

At George's suggestion I repeated the test but doing a manual Homefind instead of an automated one. Basically it seemed to make no difference so I still have my problem (not being able to move the DE axis through its full range without Position Error). Here is what I did (times are given for ease of reference to the attached logs): I turned off all power to the mount and the computer, then powered up the mount (not the motors) and re-booted the computer before running this test. 08:43 Positioned mount manually at park position (RA horizontal, with OTA on West side and DE pointing approximately at Pole) 08:44 Start Autoslew 08:45 Start motors (does Autofind) 08:46 Stop motors 08:47 Move mount by hand to approximate Homefind position (RA stays horizontal, DE just south of zenith, OTA on West) 08:48 Restart motors 08:49 Do manual Homefind for RA (using menu Servo Setup/Homefind settings for Axis RA/Find Reference Mark). Reference Mark is found OK. 08:50 Do manual Homefind for DE (using menu Servo Setup/Homefind settings for Axis DE/Find Reference Mark). Reference Mark is found OK. 08:51 In Servo Setup I Save to Ini and exit. At this point RA is horizontal, with the OTA on the West side and DE is slightly North of Zenith. Autoslew coordinates are RA05h48m14.80s; DE +51deg11'59''. Siderial tracking is on. 08:56 Using the Autoslew Move-Controls, I try to replicate the problem by moving DE South, through zenith. Speed is the default 5.00deg/sec. SAME PROBLEM OCCURS: Slew stops with Position Error (autocleared) reported. I try again. Second Position Error, this time with "Clear Servoerror" warning. Autoslew coordinates are RA 05h48m17.43s; DE +41deg18'34''. 08:58 After clearing the Servoerror. I return the DE to the zenith then try and move DE south again at slower speed (0.94deg/sec). Almost immediately the same problem occurs: Slew stopped with Position Error (autocleared). I try again, with immediate Position Error with "Clear Servoerror" warning. Autoslew coordinates are now RA 05h48m20.36s; DE +51deg22'08'' (note that the errors occurred at different points). 09:01 After clearing the servo error I turn off the motors, manually move DE just south of the zenith, turn on the motors again and try an automated Homefind to see if it results in different coordinates. Both axes are found OK. Autoslew coordinates are RA 5h56m47.66s; DE +51deg33'50'' (somewhat different to the coordinates after the manual Homefind, above). 09:04 Just in case it now works I try again to move DE South past the zenith. Same problem. 09:05 I turn motors off and exit Autoslew. The Servo log is attached. Note the following: 1. The readInt16 error spotted by George is still present. 2. The magnetic angles found by Autofind are very different to those found yesterday (particularly Axis 1). 3. The manual Homefind corrected the magnetic angle by a very large amount for RA (339) - but it still ends up substantially different to yesterday. 4. Look at the very large position errors at 08:58:22.816 and 08:58:30.070 (relating to my second, slow-speed, DE slew attempt at 08:58). The position errors for the first, higher-speed, DE slew attempt at 08:56 were much lower. 5. My automated Homefind at 09:01 resulted in no change to the RA magnetic angle and only a -1 change to the DE magnetic angle. 6. Look at the very large (3386.05 arcsecs) position error at 09:04:47.619 (relating to my final DE slew attempt at 09:04). The message log is also attached. Just to repeat my environment details: I am running Autoslew version 5.1.1.6 with ACC. The mount is perfectly balanced according to the Autoslew Servo Setup balance utility (the red bars touch for both axes). I have run Fast Tuning and also High PerformanceTuning (which did not improve the Fast Tuning settings). I have not manually adjusted the settings provided by Auto Tuning. The DIP values set by Auto Tuning for DE are 2940, 134709, 19.8 for siderial speed; 850, 39000, 4.0 for both medium and full speed. For RA the DIP values are 2940, 18000,3.6 for siderial speed and 1322, 60000, 6.0 for both medium and full speed. Noise filter is on for both DE and RA and P is stuck to I for both axes. My limits are set at: 5.0 Min altitude above horizon; 90.0 how far I can go through the meridian (90 because I am using the equatorial pier so do not need to flip) with minimum flip distance kept at the default 3.8. Check Limits is turned on (I have tried with it turned off but this makes no difference). Flip Option is set to Prefer West. My location is correctly set. My PC platform is Windows 7 Pro SP1 32bit with all Microsoft updates applied as at 16 July (I have done no Windows updates since installing Autoslew to avoid causing problems). I am using the DDM85 Premium mount with the DDM85K equatorial pier. My payload (excluding counterweights) is about 80kg. There are no physical obstructions (cables, etc) that might be preventing free DE movement. At present I have not done a polar alignment, although the ASA equatorial pier is designed for my specific latitude and is aligned to within 1 or 2 deg of north, so I am aligned to within a degree or so in both axes and my problem is certainly not caused by misalignment. Any advice on where my problem may lie would be very welcome as at present I cannot move the DE axis south of the zenith with the OTA on the west side. Nigel ServoLog2.txt MessageLog2.txt

I have still not been able to resolve my problem (not being able to move the DE axis through its full range without Position Error). Here is what I did to replicate the problem (times are given for ease of reference to the attached logs): I recycled the power to the mount and also re-booted the computer before running this test. 13:54 Positioned mount manually at park position (RA horizontal, with OTA on West side and DE pointing approximately at Pole) 13:55 Start Autoslew 13:56 Start motors (does Autofind) 13:57 Stop motors 13:57 Move mount by hand to approximate Homefind position (RA stays horizontal, DE just south of zenith, OTA on West) 13:58 Restart motors 14:00 Do Homefind (finds both axes quickly) At this point RA is horizontal, with the OTA on the West side and DE is slightly North of Zenith. Autoslew coordinates are RA 10h52m24.75s; DE +51deg33'50''. Siderial tracking is on. 14:04 Using the Autoslew Move-Controls, I replicate the problem by moving DE South, through zenith. Speed is the default 5.00deg/sec. Slew stops with Position Error (autocleared) reported. I try again. Second Position Error, this time with "Clear Servoerror" warning. Autoslew coordinates are RA 10h54m30s; DE +41deg24'30''. 14:08 I clear the Servoerror. I return the DE to the zenith then try and move DE south again at slower speed (0.94deg/sec). Almost immediately the same problem occurs: Slew stopped with Position Error (autocleared). I try again, with immediate Position Error with "Clear Servoerror" warning. Autoslew coordinates are now RA 10h57m45s; DE +51deg09'25'' (note that the errors occurred at different points). 14:11 I clear the Servoerror; turn motors off and exit Autoslew. The Servo log is attached. Look at the very large position errors at 14:04:38.747 and 14:04:43.801 (relating to my two DE slew attempts at 14:04). The message log is also attached. I am running Autoslew version 5.1.1.6 with ACC. The mount is perfectly balanced according to the Autoslew Servo Setup balance utility (the red bars touch for both axes). I have run Fast Tuning and also High PerformanceTuning (which did not improve the Fast Tuning settings). I have not manually adjusted the settings provided by Auto Tuning. The DIP values set by Auto Tuning for DE are 2940, 134709, 19.8 for siderial speed; 850, 39000, 4.0 for both medium and full speed. For RA the DIP values are 2940, 18000,3.6 for siderial speed and 1322, 60000, 6.0 for both medium and full speed. Noise filter is on for both DE and RA and P is stuck to I for both axes. My limits are set at: 5.0 Min altitude above horizon; 90.0 how far I can go through the meridian (90 because I am using the equatorial pier so do not need to flip) with minimum flip distance kept at the default 3.8. Check Limits is turned on (I have tried with it turned off but this makes no difference). Flip Option is set to Prefer West. My location is correctly set. My PC platform is Windows 7 Pro SP1 32bit with all Microsoft updates applied as at 16 July (I have done no Windows updates since installing Autoslew to avoid causing problems). I am using the DDM85 Premium mount with the DDM85K equatorial pier. My payload (excluding counterweights) is about 80kg. There are no physical obstructions (cables, etc) that might be preventing free DE movement. At present I have not done a polar alignment, although the ASA equatorial pier is designed for my specific latitude and is aligned to within 2 deg of north, so I am aligned to within a degree or so in both axes and my problem is certainly not caused by misalignment. Any advice on where my problem may lie would be very welcome as at present I cannot move the DE axis south of the zenith with the OTA on the west side. Nigel ServoLog.txt MessageLog.txt

Thanks Robert. I'll be doing more work on my DE problem today. I suspect it is a balance and tuning issue.

Robert, how did you wire the FLI plug? It has 4 pins (2 positive and 2 ground). Did you use both the Galv supplies or did you connect both the FLI pairs in parallel to only one of the Galv supplies? I'd like to only use 1 of the Galv supplies if possible as I need the other for the camera on my secondary OTA. Thanks Nigel

Thanks Robert. That's the same as my power supply so sounds good.

Still can't sort this out. I've done multiple home finds (successful), I've auto tuned the servos and checked the balance, I've checked the limits (and also tried with limits off) but I still can't get the mount to rotate through the full DE range. I keep getting "Position Error" at more or less the same point. That point varies depending upon RA position and isn't consistent. Is there anything obvious I am missing?

Yes, that's what I did and it works (except I go via the POTH so I configure it in that first).

Frustrating day today. Thought I had the mount (DDM85 Pro) behaving well. Nicely balanced, tuning seemed fine and was able to move it fully in RA and DE using the Autoslew buttons and also via TheSkyX. So I loaded up the camera and filter wheel, did a new home find, auto tune and balance but then discovered I couldn't move the Dec axis past the zenith southwards without getting autoslew "position error" and the "clear servoerror" message every few degrees. Not sure what I've done. Only software change was the installation of MaximDL 5 and the FLI drivers for the camera and filter wheel. I'll sleep on it and try again tomorrow. Nigel

Is anyone using the Galv power socket to power an FLI Proline camera? I was going to make up a cable to do this but was put off a bit by a comment by FLI on the FLI Yahoo group that the supplied AC power adaptor for the Proline cameras "soft starts" and they strongly advise against hot plugging. I'm not sure whether the DDM85 Galv supply would provide a sufficiently soft start when powered on - I'd hate to damage my brand new PL16803! Thanks Nigel

Is anyone else using the ASA ROT3 rotator (on a classical Cass) with ASCOM control from TheSkyX (latest daily update)? When I try to setup the rotator (as an ASCOM device) under TheSkyX by choosing "ASCOM Rotator" and then selecting "Astrooptik Server Rotator" in the chooser I get the attached message when I try to configure the properties (in the chooser). Nigel

Yes I used auto tuning. I've now done a fine tuning and the problem seems to have gone away. I'll keep an eye on it. I'm doing the initial setup of the whole system (pier/mount/OTA/rotator/focuser/camera/filter wheel/dome) so there are a lot of variables I'm juggling (although I'm trying to do things in a logical sequence). It may or may not resurface.

Mine is about 80kg, excluding weights, although this is well within the 100kg+ capacity of the DDM85 Premium. Maybe it is normal behaviour. There is no oscillation at all when tracking.

Bernard What is the weight of your payload and what are your servo settings?

Is it normal for a DDM85 to oscillate visibly (about 1-2 arc min on a 2-3 second cycle) when the motors are running but tracking is off? No problems at all when tracking is on. Both axes are well balanced and have been tuned.

That's about 2.5 hours away. Might be worth you making the trip once I have everything up and running. I'm taking it slowly so it will be a few weeks at least.

Hi Bernard. Where are you - I'm in 65220.

Just mounted the 400mm Cass on the DDM85 Premium mount. Bit hairy with just myself, my 2 sons and my wife but got there safely in the end. I think I'll hire an engine hoist if I need to do it again though! Now to install all the back-end equipment and then to wrestle with the software. All good fun!