AOX fan on/ fan off option

Discussion in 'Guiding and Adaptive Optics - StarChaser and AO' started by Dave, Sep 30, 2017.

  1. Dave

    Dave Standard User

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    There is an option in TSX camera add on to turn the fan off during guiding supposedly to decrease vibration. However isn't the fan necessary for proper thermoregulation of the camera and doesn't this affect cooling? Or perhaps I don't understand the fan's function. Is it safe to leave it off for extended periods?
    Thanks
    Dave
     
  2. Colin Haig

    Colin Haig Staff Member

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    Depends on which camera you have, and how solid your mounting of the cameras is, etc.
    SBIG cameras generally have really good fans with low vibration, so it's usually a non-issue, I just leave mine on.
    Many cameras also have thermal protection - if you tell it to turn off the fan, and it gets hot, it will either turn on the fan, or cut back the cooler.
    Some cameras are stupid, and will heat up to the point where the cooler stops functioning (it can't maintain a temperature difference). I've never heard of a failure, but suppose its possible.
    If you run with the fan off, the CCD will warm up to a certain point - there will be an equilibrium reached because the hot side of the peltier cooler can't get rid of the heat fast enough - that's why the big heatsink fins and fan.
    My recommendation: Leave the fan on, and work on improving your mechanicals, PEC, guiding first. Its usually worse than any fan vibration.
     
  3. Wannaberocker

    Wannaberocker Cyanogen Customer

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    Dave..............I actually had to replace my fans on my STT-8300, I was chasing what I thought was a guiding error and could not pin down where it was coming from until I noticed the stars were elongated no mater what the exposure length was I was using. Then I shut the fans off and the elongation disappeared completely, so yes these fans can most definitely vibrate to the point of actually being worse than any polar alignment error or PEC error. I bought my replacement fans from DigiKey.com as per Tim. The replacement fans were ball bearings instead of the stock bushing type fans that are placed in these from factory. I could actually feel my entire scope vibrate at the opposite end using both fans made it even worse as the oscillations were so bad you could hear them actually harmonizing in and out of key lol. Cheers!
     
    Last edited: Oct 14, 2017
  4. Dave

    Dave Standard User

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    Interesting. Thanks for the info!
    Dave
     
  5. Doug

    Doug Staff Member

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    FYI the bushing fans typically have lower vibration than the ball bearing fans. A failing fan bearing will of course cause abnormal vibration.
     

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