Fan vibration

Discussion in 'STX and STXL' started by CraigNZ, Mar 26, 2017.

  1. CraigNZ

    CraigNZ Cyanogen Customer

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    I have an STXL-6303e that has developed over the last few weeks a considerable fan vibration, to the extent that the autoguider shows a wavy line instead of a round star. If I turn off the fan (in software) the vibration stops and the star is round again.

    For now, I am temporarily using the software to turn off the fan during imaging, but I'm not sure if this will cause over- heating problems for the camera. It seems to hold temp (at -5C) well enough, but not sure if this is advisable for a long term solution.

    I removed the fan for cleaning and inspection and noticed it is somewhat isolated from its case using felt strips but they are not enough. I don't see any damage to the blades and they are now spotless after cleaning, but it still vibrates, so I suspect a bearing is gone. Is there any other solution recommended or do I need to get a replacement fan?

    Craig
     
  2. CraigNZ

    CraigNZ Cyanogen Customer

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    I noticed in a separate thread that CCDOPS does have a feature for controlling the fan speed. I normally use SkyX for all my camera control, and it only lets me turn the fan on/off. I installed CCDOPS and sure enough, I was able to set the fan speed to 30% which took out all the noticeable vibration. I could exit CCDOPS with the fan speed intact, but as soon as I used SkyX to connect to the camera, the fan speed returned to full speed. Is there any way to either a) have SkyX set the fan speed, or b) keep the fan speed intact when using CCDOPS/SkyX? Ascom driver maybe?

    Craig
     
  3. Doug

    Doug Staff Member

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    CCDOPS and MaxIm DL can control the fan speed. I would check with Software Bisque about TheSkyX - they may have a setting somewhere. It's probably defaulting to the "Auto" setting right now.

    It sounds like the fan may have developed a bad bearing. I would recommend replacement.
     
  4. CraigNZ

    CraigNZ Cyanogen Customer

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    Thanks Doug, I will do that.
     
  5. blackdragon72

    blackdragon72 Standard User

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    Doug,

    Has this been fixed in either firmware update or some other form?

    I think this is exact problem I have been struggling. I got almost up-down elongated stars across the FOV and you confirmed CCD has no tilt.

    Is the setting lost only after power is off? ie, can I set it in CCDOps and then switch another program to retain the setting?
     
  6. blackdragon72

    blackdragon72 Standard User

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    I checked SGPro does not have fan speed option.
     
  7. Doug

    Doug Staff Member

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    Yes if you set it in another program such as CCDOPS, then when you switch programs it should stay as set.

    (Assuming that other program doesn't change the setting when you connect... but if they don't have the setting in their user interface, it's rather unlikely that they will send the command.)
     
  8. Mike Hambrick

    Mike Hambrick Cyanogen Customer

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    Hi Craig and Doug.
    I hope you don't mind if I jump into this discussion because I have had a similar experience with my STXL16200. I had been noticing that the fan on my camera would kick into high speed from time to time causing a very noticeable vibration in the whole imaging train. I watched what was going on when this was happening and observed that the fan speed increased when the temperature controller output stayed above about 78% for a period of time. Once the output dropped below 78% for a minute or so the fan speed would drop back to normal.
    When you say that we can control the fan speed with CCDOps or Maxim DL how does this work ? Does it only allow you to set a constant output ? I would really like to be able to put a clamp on the temperature controller output so that it can never exceed a certain percentage. In my case I would set this clamp at 75% to make sure that the fan never jumps into high speed. Doing this might mean that it will take a little longer for the camera to cool down but this would mainly only be when I am starting up.
     
  9. Doug

    Doug Staff Member

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    The fan has an auto mode, or you can set it manually to a certain percent speed. Expose tab Options menu Camera Settings.
     
  10. blackdragon72

    blackdragon72 Standard User

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    Doug,

    What is the impact on setting fan speed too small? Is it going to cause any potential damage to the sensor? And what is the rule of thumb of setting fan speed?
     
  11. Doug

    Doug Staff Member

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    The main impact is that you won't achieve the same level of cooling with less air flow. I don't have a rule of thumb - you just have to experiment. I would use the highest speed that doesn't cause vibration. Also be aware that if there are any mechanical resonances in your telescope an intermediate speed might possibly be worse.

    There is no danger to the sensor itself. The camera firmware is supposed to protect the electronics against overheating. Of course as a general rule I don't recommend solely relying on firmware safety systems, because you never know what could happen. If the fans aren't running the cooler should be turned off.

    (The undervoltage protection for the cooler power supply is done in hardware - that's why you have to cycle power if it triggers. The temperature sensors require the processor to read them, so they have to be monitored by the firmware.)
     
  12. blackdragon72

    blackdragon72 Standard User

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    How do I know if "undervoltage protection" has been triggered?
     
  13. Doug

    Doug Staff Member

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    Don't worry about that - the cooler would simply shut down. It would only happen if the power brick failed or you used inadequate extension cables. My point was that the camera's overheat protection is a mixture of hardware and software functions.

    Since the heat sink over-temperature protection is a software function, I recommend being more cautious. It's extremely unlikely to fail, but just in case you should always turn off the cooler if you turn off the fans. As an engineer I'm paranoid about such things. ;)
     
  14. blackdragon72

    blackdragon72 Standard User

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    Stars looked great if I turned of cooling and fan (but image is very noisy so hard to tell). With 30% fan speed, fan seemed quiet but stars did not look good, no significant improvement comparing to auto speed. This was tested on AP1100 mount.

    So I think it is a real issue for STXL CCD family (you can not get a better mount than 1100 for mobile setup). What are the options to fix it? Is there any other low noise fans out there?
     
  15. blackdragon72

    blackdragon72 Standard User

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    And for this type of problem, you should put it in a sticky Q&A thread, for anyone has similar issue can find it quickly.
     
  16. Doug

    Doug Staff Member

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    That doesn't make a lot of sense to me. No one else is reporting major problems with fan vibrations. I use an AP mount and no issues whatsoever.

    Can you post a photo of your rig?
     
  17. Doug

    Doug Staff Member

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    We've been looking into this further. The fan is mounted with a "shock absorber" material, which could be a factor in this. Is the fan loose inside its housing?
     
  18. blackdragon72

    blackdragon72 Standard User

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    I dont have picture of my setup in front of me. I will post later. It is FSQ106ED+FT focuser+16200 on AP1100.

    Do you have instruction how to open the case and check fan sitting?
     
  19. Doug

    Doug Staff Member

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    Just undo the four screws on the fan housing. The fan should be firmly held in place by the foam.
     
  20. blackdragon72

    blackdragon72 Standard User

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    Doug,

    Are you talking about 4 black screws, or silver screws?

    I removed 4 black ones and fan just came off, nothing to hold it.

    When I power on the CCD, I can easily feel the vibration when touching filter wheel (ie, I know fan is running by touching), it is not obvious when touching telescope focuser. But I am not sure whether this is issue.
     

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