I am a postdoc working with the Dragonfly team, specifically, the broadband component. A handful of our cameras have started having issues with regulating their temperature (around 15 units), and we are wondering if we might be able to send some units in to you for troubleshooting/repair. For reference, most of our 48 cameras are STT-8300, and a handful are STF-8300. Please let me know if there is any additional info I can provide!
Hi Will, Always happy to help. Do you know what the ambient temperatures were vs cooler set point vs measured cooler temperature? (Am assuming this is also at altitude of around 2000 metres, which decreases the air density, and thus cooling is less efficient). Temperature regulation can be a problem if the camera's maximum Delta T has been exceeded. This may occur at high ambient temperature with a low cooler set point. (Apologies, you probably know this). The STT usually does better than the STF. e.g. STT delta T ~50C. So if ambient is +20C at night, the maximum cooler set point would be perhaps -25C to allow some headroom. (20 - -25 = 45C temperature difference). e.g. STF delta T ~30C. So at +20C, setpoint should not excced -10C otherwise the fan cannot get the heat out of the heatsink etc. e.g. Aluma CCD694 delta T about 50C. So before shipping something in for repair, I'd recommend looking at the FITS Header data (assuming your Dragonfly code captures the CCD temp, setpoint, and possibly the heatsink temperature and input voltage if available - not all cameras have all that). A bench test of the "problematic" cameras at NMSkies would be worthwhile - to check if it is dirt in the heatsink / fan, fan failure, or just maxxed-out Delta T. You can send me image data/dropbox it to chaig (at) diffractionlimited (dot) com. NMSkies was about 86F (30C) last time I checked... so it could be the cooling is maxxed out; the cameras may shut down the cooler to protect themselves; or the power supplies may not be providing enough juice. If genuinely there is a hardware issue, please get a list of the camera serial numbers together, and then we'll send you a link to RMA the equipment.
