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MarkS

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  1. This may or may not be much help, but I have been using a DDM60 in mobile systems for some years, and I evolved by trial and error a start up procedure which guarantees a clean start up. I transferred the procedure to my DDM85A rollabout system and it also works every time. An important feature is that once everything is connected together, the mount power is turned on BEFORE the computer power is turned on. This always seemed to guarantee clean a start up, whereas failure to do this could cause problems....... I never found out why, and I just did what worked. Mark
  2. Hi Stephan, I don't have a TCF-s focuser, but I use a FLI Atlas with Sequence. You need to find by experiment how Sequence interprets the number of steps in mm. With the Atlas, I found that Sequence 'thinks' 1000 steps is 1mm. In fact 1000 steps of the Atlas is 0.083mm. I then had to enter appropriate Coarse and fine AF steps in Sequence settings. These were 24mm and 12mm respectively. The actual movements of focus are 2mm and 1mm. These amounts gave good AF results. Also, because the Atlas is so slow, I had to increase the focuser time-out to 100sec to prevent overflow error messages. I also increased the Maximum Way from Startpoint to 10mm. (ie actual 0.83mm). You will need to find the right numbers for your focuser - but I hope this helps as a guide. Mark
  3. With a heavy load, balance is very critical on both axes, particularly RA. The total load (OTA plus camera etc) should not exceed 28 kg for the DDM60. Overloading these mounts must be avoided!!! Read the recent discussion on balancing - I think it's the 'DDM85 position crash'. It is definitely a case of near enough is NOT good enough! Balance is critical. Tuning the motor parameters is well covered in the manuals. Always worth a read, even if one knows what one is doing, but I suggest you don't try to push the PID numbers too hard - the system will tell you that you have gone too far by going into oscillation. I'm not sure, but I suspect that very high PID settings may exacerbate motor current increases over time. Relaxation slews at intervals during a run is good practice. I'm not sure what you mean when you say that the problem mostly occurs close to the horizon. Why would you image there? If you try to send the mount too close the lowest altitude limit, it will get into trouble. In any case, for good imaging it is best to limit altitude to above 40 degrees or so. I set the limit in Autoslew to 25 degrees, but never image below 40 degrees. Hope this helps. Mark
  4. Recently I had to go through commissioning a new laptop. I thought I knew what I was doing as I had been using two ASA systems for years. It turned out that I had forgotten about some critical but simple steps, and after the mount heading off for the wrong hemisphere and refusing do what it was told, I gave up and called Wolfgang at ASA for a Teamviewer session. He sorted it in about 2 minutes - much to my shame! The basic problem was, that in spite of having all the software and program data properly installed, it is critical that you 'Set new Homeposition' after having done the Homefind and then pointing the scope at the zenith or some star. This may or may not be your problem, but the erratic behaviour points something of this sort. Others may have better ideas, but in any case it won't hurt go through the manual and check that the fundamental first set-up steps have been followed. Only then should you start looking for subtlties🙂 Mark
  5. Try setting park1 as your horizontal OTA position, and set Park2 to the zenith Mark
  6. You could leave Park1 at the zenith, as it is useful for testing, and use Park2 as your parking position. Mark
  7. PS: Read the thread on DDM85 position error crashes. Cheers, Mark
  8. What load is the mount carrying? These currents look high to me on both axes. My DDM 85A carries an OTA and camera with a total weight of about 28kg - which is a relatively light load. Current on the DE axis is usually below 0.3A, and on the RA axis usually below 1.2A. The currents are dependent on load, however I do not know what the current vs. load curve is. Mark
  9. I have an ASA 0.73 Reducer, and its dimensions are exactly as per the ASA drawing. Are you sure what you have is an ASA reducer? Mark
  10. Robert, I definitely get best long term performance if I finalise RA balance by running the system for an hour or so on each side of the meridian, and adjusting counterweights until I get the most equal current draw over time on each side. I find that in the Southern Hemisphere the optimum current occurs when the counterweight slightly favours the East side. See my above post also. Mark
  11. I did not want to suggest bearing problems until you tried everything else. I hope you can resolve the problem even if it means the mount must go back to ASA. I can understand your frustration with lockdowns - here we have a 5km limit on travel, so I have not been able to get to either of my sites for 3 months.....they are not remotely operated Mark
  12. It is very unlikely from my experience that small DE imbalance will cause RA tracking failure. Your Clservo log shows that the Axis 2 currents generally remain <2amps. You could probably refine the DE balance - concentrate on the OTA horizontal position. Your on-site assistants need to realise how critical the balance is. Adjusting DE balance by moving the OTA is tedious and tricky. 1mm can make a significant difference. RA Balance definitely needs refining. It also needs very fine adjustments to the counterweight position. My procedure - which is not done remotely - is to use the Balance Tool with the counter weight bar pointing east and then west. The best position of the counterweight is different for each side. I set it between the two positions, and then let the mount track for a long time. I have a 0-5amp digital ammeter in the 12V power line to the mount, and I watch and record the current over time. If the current starts to run away, I move the counterweight accordingly. I then do the same on the other side of the meridian. This enables me to refine the counterweight position better than the Balance Tool does In my case the final optimum favours the east side (I'm in the Southern Hemisphere) slightly. In regards to 'relaxing' the mount, there are two important issues. Firstly, it is vital not to set the tuning parameters too tight (PID numbers too high). I have found it better to set the tuning manually. Generally the heavier the load, the tighter the tuning needs to be. But I would always try to set the lowest tuning numbers I can while still obtaining good tracking for up to 15 minute subs. The load on my DDM85 is approximately 29kg, whereas your is at least 42 or so (OTA + FW + Camera + bits and pieces) so I don't require as tight tuning as you. But I suggest you experiment with lower numbers. (Incidentally, the sensitivity slider on my set-up is 1 degree for both axes.) There is another important setting, particularly for heavy loads. In Sequence you can program periodic 'Stick/Slip' slews, which are designed to relieve excess current build-up during long runs. You can program intervals between the slews and the distance in degrees for the slew. Then during the run every,say 40min, the mount will slew 5 degrees, or whatever you set, and back again. I include the routine on both my DDM mounts, one which is relatively heavily loaded (DDM60), and the other, (DDM85) which is lightly loaded. If you are not using Sequence, I strongly advise you to program such a feature into your routine. Mark
  13. The log shows that every instance of a position error is associated with the RA motor current increasing to 5Amps. In normal slewing or tracking this level of current should not be reached by either motor. It also appears from the error log that the slew to -38.2 degrees stops at ~-42. This raises several questions: 1. Is the mount running into an obstruction during the slew? Are there trailing wires which could snag? (this may seem a silly question, but it has happened before) 2. Does this behaviour occur at other positions? 3. Does it ever happen while tracking, or only during a slew? Current running away during a slew is most likely due to an obstruction. The logs support this possibility, as the mount seems unable to get past -42 degrees when it is trying to get to -38. This sudden behaviour occurring during a slew is almost certainly not due to imbalance unless that imbalance is seriously high. RA current running away during a long tracking period is usually due to imbalance, but it happens gradually until the mount mistracks. This can occur even if the balance is only a little off. With a heavy payload this type of failure is more likely than if the mount is not heavily loaded. Check that the payload is within the mount specification. The problem is unlikely to be software. If you have not already done so, I suggest you test the system during the day by slewing and tracking at varying positions and obtaining Clservo logs for the whole time you are doing the tests. You need to see what the logs show when the system is working properly as well as when it fails. Do you have a camera in the observatory so you can see what the system is doing? Hope this helps
  14. MarkS

    Fan speed

    Mike, The Moravian camera fans are internally connected to the 12V power supply in the camera. That is, they are NOT externally controlable. The camera must run on FIXED 12V. It should never be connected via the ASA fan port, which is intended to run telescope fans only. Mark
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