Resolved AllSky-340C dome heater not working

Discussion in 'Specialty Cameras SG-4, AllSky, ST-I' started by Mark Marfoglia, Dec 8, 2018.

  1. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    I am running version 1.0.37.0 on a Windows 8 machine. I have been careful to run it only at night in the summer, but run it full time in the (Canadian) winter.

    Lately I noticed that my dome heater is not working as it no longer melts the snow and barely clears a small “hole” in the center. I cycled the camera connection and 12V feed but no change.

    The control software indicates that it is active but the results show otherwise. Is there any software fix I can try or do I have to send it for repair.

    Here is an image taken at -6C.
     

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    Last edited: Dec 10, 2018
  2. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    Tim,

    As the winter progresses, I will have less and less ability to access this camera as I need to erect scaffolding to get to it. I would like your response soon if possible.

    Thanks,
    Mark
     
  3. Colin Haig

    Colin Haig Staff Member

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    Mark, did you check the +12V feeding the camera is good, e.g. with a voltmeter while the heater is on?
    If the power supply is good, then another thing to check is the power connection to the camera.
    Sometimes the power connectors get a bit of crud/surface corrosion/dirt/moisture in there.
    It might be worth pulling the power cord out, using a tiny bit of contact cleaner spray on the plug, and wiggle the connector a bit as you put it back in.
    Am not sure if silicone dielectric is a good idea on those things or not, but I use on some other outdoor observatory connections.
    And am fed up with grey skies here in southern Ontario...
     
  4. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    Colin,

    Is there no forum that you don’t monitor? Don’t get me wrong, I appreciate the advice.

    The power supply is working on the observatory end, but I guess I no choice but to get up there and check the connection, which requires a scaffold to do safety. You are right it probably is the connection. It’s just so inaccessible. A lesson for those planing an observatory.

    I have DETOXIT. However, I am hesitant to use it because it desolved the glue in my Planewave connectors in the past and they came apart. I thought I was doing preventive maintenance and ended up with a problem. Planewave gave me the replacements and only charged me the shipping which was very good of them, but the interruption was not fun. That stuff is quite strong so I am careful how much I use now.

    The weather is terrible here as well. When I started this hobby 10 years ago, my first revelation was that nobody told me how hard it was to get clear skies in Quebec. I have learned the hard way, but stubbornly keep at it...

    Mark
     
  5. Doug

    Doug Staff Member

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    Mark,

    Try cleaning the contacts. If that does not work then it may have to come back to the shop for inspection / repair.

    Doug
     
  6. Colin Haig

    Colin Haig Staff Member

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  7. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    Colin,

    Thanks for the link as I have been looking for a product that can fly with me and they make a pen.

    My bad, that’s DEOXIT not DETOXIT, and it is supposed to be ok for plastics. However, the glue the cements the connector together dissolved.

    I will report back once I can get at it on the top of the 18’ pole.

    Mark
     
  8. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    Doug,

    I accessed the camera and the moisture is inside the dome. The contacts appear to be clean and the 12V is good. I will use some DEOXIT to clean the contacts but I have to get that moisture out.

    Is it advisable that I open it up to dry it out?

    Mark
     
  9. Doug

    Doug Staff Member

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    Probably a good idea. It is simple to remove the dome - just remove the screws holding the retention bracket.
     
  10. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    Doug,

    I opened it up and cleaned everything.

    I removed the black plate as well to get at the chip on top. It has a wire lead so I thought it was the heater. I connected it up and powered on the heater to test it. The chip did not heat up really, but there seems to be heat coming from below. Is the heater inside the casing? Is the chip a sensor instead?

    I would like to test it to see if it has to be sent in.

    Thanks,
    Mark
     
  11. Doug

    Doug Staff Member

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    Could you send me a pic of the "chip"?
     
  12. Doug

    Doug Staff Member

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    Oh, and make absolutely sure the heater is enabled in the software...
     
  13. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    For sure the heater is on. I have made a sketch instead. It is a small chip at the camera base. Any clue what this is?

    I noted that 2 screws on one side of the 4 screws that hold down the top plate were not tight, and that water had entered between on that side. Water cannot of course go uphill (ie up the sloped base plate), but it is not sealed. No rubber, no grease. I am wondering if I can use plumbers grease to seal there or if it is made to "breath"?

    I left the scaffold up for now. I regret having put it so high (it's actually at 21'). Access is a problem. It is working fine now and has stayed clear for 2 days, of rain mostly, heater always on.
     

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  14. Colin

    Colin Cyanogen Customer

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    Hi Mark,

    Yes, the chip you have described is the heater for the black base plate. It is designed to warm up the plate several degrees to dissipate and evaporate any moisture inside the dome. The bottom of the chip has a silver coloured metal plate screwed to the black base plate which transmits the heat. You will not feel a large amount of heat from the chip itself, but if the plate is warming up, the heater is working. For reference, I tested a unit in the lab and the black base plate reached ~32degC measured with an IR temperature gun while indoors at an ambient temperature of ~22degC. Please make sure that the heater chip is tightened snug, if it is loose it will not transmit heat properly.

    The AllSky-340 is not designed to be air sealed in the dome. In fact, there are vent holes in the bottom of the dome enclosure that will allow moisture to escape.
    The four screws holding the top plate down should be snug, it is possible that excessive moisture was entering the dome if 2 of the screws were loose. We do not use any grease or rubber seals on this junction.
    There is however a rubber o-ring seal for the clear dome, as this junction is horizontal (not sloped like the 4-screw plate).

    As you have reported that the unit is currently operating correctly, albeit in rain and not snow, it is possible that cleaning the heater contacts improved the heat output.
    Please keep us posted on the performance when the snow returns!

    Kindly,
    Colin Wolfson
     
    Last edited: Dec 21, 2018
  15. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    Colin,

    The moisture is less than before, but it did accumulate again inside the dome. I have opened it up and will leave the dry inside for several days to see if that helps. It has been nothing but precipitation here for months.

    I think the heater is working as it slowly melted away the snow that fell on top within about 5hrs of it falling.

    I did notice that the sloped portion between the plates was completely wet again. I can’t help but feel that when it is warm the moisture gets in from there and then freezes on the dome when the temperature drops.

    Clear skies,
    Mark
     

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  16. Colin

    Colin Cyanogen Customer

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    Hi Mark,

    Indeed there does appear to be moisture in between the plates. I would suggest trying a thin layer of waterproof silicone grease on the mating surfaces.

    Colin
     
  17. Mark Marfoglia

    Mark Marfoglia Cyanogen Customer

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    Colin,

    I did 4 days ago and it has held up to a substantial freezing rain storm already, with no new moisture inside the dome.

    I note however that when we get freezing rain/ ice pellets that accumulate on the dome, it can take a few days for it to clear fully. Now that I know what the heater looks like (relatively small) I assume that this is normal because of the sheer volume of ice to clear. In hindsight, I should not have placed it 21’ up.

    I guess this item is resolved. Thanks for your help.
     

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