STX16803 current surge?

Discussion in 'STX and STXL' started by blackdragon72, Jun 25, 2020.

  1. blackdragon72

    blackdragon72 Standard User

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    What is the max current 16803 may need?

    I want to power 16803 from 12V battery. The battery has 10A fuse, it is fine if powering up without USB connected, but it blows fuse as soon as USB is connected, or powering up with USB connected.

    Do you see any issue powering up 16803 with 12V deep cycle battery? And what fuse should be used?
     
  2. Colin Haig

    Colin Haig Staff Member

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    You've got a short in your wiring in all likelihood, or miswired the connector.
    The metal shield of the DIN connector is not connected directly to the 0V (negative lead). The camera 0V is not attached directly to it's case - there is RF filtering etc, and when you plug in the USB, you are shorting to ground.
    This can destroy the USB interface on the camera.
     
  3. blackdragon72

    blackdragon72 Standard User

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    Do STL11000 and 16803 work in the same way? I tried it on 11000 on it works fine.
    I am still not clear why it has issue only when the camera is connected to PC via USB. If there is wiring issue, shouldnt it fail same way without USB connected?
    The camera is still working fine when I use 16803 AC adapter.
     
  4. Doug

    Doug Staff Member

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    If there is a short between +12V power and the connector shell, the power supply will short out when the USB connector is plugged in because they share the case ground. The +12V shorts to the computer's case ground, which completes the loop.

    I suggest you take apart the 12V connector that goes into the camera, and check for a possible short to the shell.
     
  5. blackdragon72

    blackdragon72 Standard User

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    I will confirm, but I measured there was not short between Shell, 12V and 0V.

    Why 11000 does not have this issue? It works fine. I could connect and control camera.
     
  6. blackdragon72

    blackdragon72 Standard User

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    Or is it possible that some key components are turned on when USB is connected and create power surge? 10A fuse is probably marginal for 16803, but good enough for 16200 and 11000.
     
  7. Doug

    Doug Staff Member

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    Turning the camera on should not create a large surge - high power draw only happens when the cooler is ramped to full power.

    There could be a brief surge as the input capacitors charge up. You could try a slow-blow fuse to see if that is the cause.

    But the fact that it only happens when the USB is plugged in is suspicious, in terms of a short circuit. Is it possible that the short is intermittent? Perhaps it only shorts when you plug the connector into the camera.
     
  8. Colin Haig

    Colin Haig Staff Member

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    Check you don't have a short between the shield of the din plug and 12V. The STX and STL are designed differently.
     
  9. blackdragon72

    blackdragon72 Standard User

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    It also blows the fuse when powering up the camera with USB connected.
     
  10. blackdragon72

    blackdragon72 Standard User

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    How about STX vs STXL?
     
  11. Doug

    Doug Staff Member

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    It doesn't matter what order you do it in. It still shorts out.

    They are the same design.
     
  12. blackdragon72

    blackdragon72 Standard User

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    I am wondering if you have current measurement in each case, esp transient current surge.
     
  13. Doug

    Doug Staff Member

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    I don't have a measurement for you, but it will be insignificant. The total capacitance on the raw 12V input is only about 150 uF. The main switching regulator uses a soft-start function, and the cooler power is not turned on at power up.

    The fact that it blows the fuse when you plug in the USB after the 12V proves that this is not an inrush current problem. There's a short circuit.
     
  14. blackdragon72

    blackdragon72 Standard User

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    I checked and there is no short circuit in 12V power cable. Problem with USB on PC, or any other possible cause?
     
  15. Doug

    Doug Staff Member

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    Does the camera work with the power brick that came with it?
     
  16. blackdragon72

    blackdragon72 Standard User

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    Yes, it works fine.
     
  17. Colin Haig

    Colin Haig Staff Member

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    Two final thoughts:
    What happens if you remove the metal DIN plug shield from the connector you made - and just gently press the DIN pins (usually on a black plastic disc) into the camera?

    Have you checked you didn't accidentally get the pins flipped around? e.g. misread the orientation from socket vs plug numbering
    e.g. compare the +12V / 0V output from the standard AC power supply to the way you wired your cable.
     
  18. Doug

    Doug Staff Member

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    Exactly. There is clearly something wrong with the cable you built. Compare the voltages on the pins on the factory power supply to those on your cable.
     
  19. blackdragon72

    blackdragon72 Standard User

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    The cable works fine for 11000 so voltage is good. I also measured and confirmed.

    Is it possible for you to measure current surge? I am still think 10A might be just marginal for STX CCD.
     
  20. Doug

    Doug Staff Member

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    We don't have something that can measure it readily.

    The camera is rated at 12V, 10A. You need to use a fuse rated at least 20% higher than the maximum load.

    I'd go with a 15A fuse to be safe.
     

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