STT 8300M Cooling Problem

Discussion in 'STT Series' started by William Clark, Dec 6, 2015.

  1. William Clark

    William Clark Standard User

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    My 8300M is getting harder and harder to cool. When I activate the cooler to -25 my normal setting it begins to cool and then shuts off. I have to wait until the power consumption drops to 30% or so and turn it on again, several times. In the past few nights it takes several attempts to cool to minus 25 and then once there it will stay cool for a few minutes or so and then shut off on its own. It is -4 degrees C a night here now and the STT now struggles to get to -25. The power level of the batteries running the system is optimal as they are brand new 12V gels. Any ideas, on what the issue might be? Thanks Bill
     
  2. Doug

    Doug Staff Member

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    Can you measure the voltage on your 12V battery input? It kinda sounds like it's drooping when the camera goes to full cooler power.

    Please try it with the power supply that came with the camera. That will indicate whether it's a power problem or a camera problem.
     
  3. giranda

    giranda Standard User

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    I am interested in this response I have been having the same issue with my STT-8300M. If the power ramps up to 100% for any period of time it shuts the cooling off. Then it shuts off occasionaly throughthe night. This will happen at temps 30-40 below ambient. I am running off of the power supply that came with the camera. It is interesting that this behavior only happens when I run the power through the mount using the through the mount cabling. I am using an Paramount MX+. The through the mount power cord is supposed to transmit up to 5A. I notice the STT draws 3.5 A, and its power supply is rated for 6.0 A. I have an FW8G filter wheel attached, but am not sure of its amperage draw.
     
  4. Doug

    Doug Staff Member

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    Check the voltage indicator LED, and make sure the voltage isn't dropping when you hit 100% cooler power. Despite what the manual says, the through-the-mount wiring may not be large enough gauge for full power. (I use my own cabling for that very reason.)
     
  5. giranda

    giranda Standard User

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    Very helpful, why didn't I think of that! The indicator is yellow when using the through mount cabling.

    I noticed the camera voltage indicator gets yellow, when the power draw is 100%, even if I am using the power supply original cable (and supply is plugged into my house electric). I this normal? Should I consider replacing the power supply? The cooling does not go off when connected like this even though the indicator gets yellow.

    What gauge wire do you use for your through the mount cable?
     
  6. Doug

    Doug Staff Member

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    My through the mount cabling is something like 12 or 14 gauge stranded. Nice and thick.

    If it's showing yellow all the time then maybe the main problem is the power supply.
     
  7. giranda

    giranda Standard User

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    It shows yellow when it gets to 100% power draw on the TE - should I order a replacement? Otherwise it is off.

    The through the mount cable shows yellow all the time (41% power draw).
     
  8. giranda

    giranda Standard User

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    Let me write a little more clearly. When connected directly to the power supply, the voltage indicator light gets yellow only when the TE is drawing 100% (or near 100%) power. When the TE power draw is lower, the voltage indicator light is blank (off). However, when the camera is connected via the through-the-mount cable the yellow light stays on all the time. So there is definitely a voltage loss when the stock through-the-mount cable is used.

    One other interesting fact. When I was out last, the camera would shut itself of about every 10 minutes or so (sort of randomly). I tried a few things, and found that if I switched to guiding photos every 2 seconds (from every 0.5 seconds) the camera would continue to work. When I switched back to every 0.5 seconds it would occasionally shut down in a random way as before. I went back to 2 second guiding, I was able to finish the night (about 5 hours) with no other incident. I was wondering could this also be a power issue?

    So, do you think I should order a new power supply? Thanks for your help.
     
  9. Doug

    Doug Staff Member

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    Well first I'd try running the camera without the through-the-mount cabling.
     
  10. giranda

    giranda Standard User

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    Sorry, I am not clear. I have been running the camera without the through-the mount cabling. In this case (where I am NOT using the through-the-mount cabling), the yellow low voltage indicator diode comes on when the TE power gets to 100%. Once it reaches temperature, and the power consumption starts to drop, the yellow voltage indicator light goes off. I seem to be able to collect images fine in this configuration (except the odd behavior mentioned above with the autoguiding, which was run NOT using the through-the-mount cabling)

    In the simplest form, my question is:

    Is it normal for the yellow low voltage indicator light to come on, when the TE power consumption is at 100%. If it is not normal, then I will purchase a new power supply.

    Thanks again for your multiple quick responses.
     
  11. Doug

    Doug Staff Member

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    Yellow means the voltage is below 11V, so it really should not turn on. Probably your best bet is to replace the power supply.
     
  12. giranda

    giranda Standard User

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    Doug,

    Thanks for the help. I have ordered a power supply. I will report back if it does not solve the problem.
     
  13. giranda

    giranda Standard User

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    I replaced the power supply, and the yellow low voltage indicator light does not go on as much. In addition, I can cool to -30C (approximately -47 from ambient) using the through-the-mount cable. So overall a success. The steady state power draw is about 61% under these conditions.

    When connected directly to the camera, the yellow indicator still comes on briefly when the TE power draw is ramped up, but does not stay on. When using the through-the-mount cabling, the yellow indicator light stays on whenever the TE power is higher than about 40 %. However, the cooling never shuts off like it did before.

    Re-reading the documentation, I noticed the STT has a built in voltage regulator. I was wondering if I could maintain the voltage better if I just used a more powerful DC power supply (my old one was 72 watt, and the new is 85). What if I just used a 120 watt supply?
     
  14. Doug

    Doug Staff Member

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    The power supply will indeed attempt to maintain 12VDC at its output. But that's not necessarily what will reach the camera.

    At the far end of the cable the voltage will depend on how much loss there is in the cable. That in turn will depend on how much current the camera draws (the cooler is the biggest draw, so higher cooler power means more voltage drop). It will also depend on how thick the wires are (thicker is better) and how long the cabling is (shorter is better).

    A larger power supply might have slightly better regulation at full power. But most of your loss is probably in the cabling.
     
  15. giranda

    giranda Standard User

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    Thanks again.
     

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