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Thread: Help with USB Hub power issue

  1. #1
    Newbie millc5's Avatar
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    Help with USB Hub power issue

    All,
    I am going crazy trying to figure this out. I have an Opus POL 5v 15W supply to a usb hub. This is fed from ACC line. When I kill ACC the computre stays on for 10 minutes or so due to my DSSC which I installed as well. The problem is when the ACC gets killed, the power to the hub is cut, but then the computer feeds 5v through the USB cable, to the hub, and back through my ACC circuit. This causes my AMP and other items to stay on, and I can not exit and lock the car.

    I have tried cutting the USB + line @ cpu, not go, devices do not work on hub. I have tried relay energized by ACC, no go, stays latched due ot 5v on load...Please Help.

    Thanks,
    Rick

  2. #2
    Maximum Bitrate DeltaFX's Avatar
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    Ahem...Are you saying the 5v from your puter enters the hub, then exits the hub back to your POL, then is transform back into 12v (a POL is reversible ?) to your ACC ? Gnh ???

    I do firmly believe there's a serious flaw in the Physic involded the way you describe your problem.

  3. #3
    Newbie millc5's Avatar
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    DeltaFX,
    Not exactly, it allows the 5V back into my ACC circuit thru the POL and the Hub, which is enough on my AMPs ACC in to keep it on since it already has 12v constant.

    This was very surprising to me, both the hub and the POL seem to allow the current to travel back through thier respective circuits.

    When I unplug the USB cable from the PC at the hub, the amp turns off.

    Thanks for the reply.

  4. #4
    FLAC
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    power the 5v rails remote turn on from the 12v rail of the PCs power supply. That way it turns on when the PC turns on and turns off after the PC

  5. #5
    Newbie millc5's Avatar
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    Will
    That would work, but does not solve my problem. I need the AMP, etc. off when I shut the car off, the PC will stay on until uSDC20D timer expires. If I use the PC to power the curcuit, it will still stay on until the uSD20D cuts power to my inverter.

    here is a small diagram:
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  6. #6
    Variable Bitrate StrataG's Avatar
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    Are you using the accessory lead as both power and remote turn on? If so that is your problem. If you are only putting the accessory line into the remote on, it should not be feeding back. If it is going into your power line then you will get the behavior you describe. Outside of wiring things properly (i.e. wire from battery->power input, accessory->remote on), you would need to use a diode to prevent the electrical flow out from the POL from the power input side.

    Also are you sure your LCD takes 5V? Most that I've ever seen have 12V inputs.

  7. #7
    Newbie millc5's Avatar
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    StrataG,
    Thanks for the catch, its not my LCD, its my usb DVD drive on the POL 5v with the HUB. I also updated my drawing, the AMP I have is 5.1 and has remote and ACC inputs. I have RMT running from the uSDC20D and ACC direct from my ACC circuit. As I mentioned, when I unplug the USB cable from the hub after cars is turned off, my amp shuts down so I know the source of the power is the PCs usb cable.

    Thanks

  8. #8
    Variable Bitrate StrataG's Avatar
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    First off, your dvd drive and usb hub are most certainly overdriving your POL. They are meant to handle 3A, and each of those devices require about that much. I'm suprised you're not having trouble booting up as well.

    As far as your wiring, please describe what is wired to what (specifically input wires) on the POL. I have a feeling you have your accessory line wired to both the remote and power wires on the POL as that is how it appears in the diagram.

  9. #9
    FLAC
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    and why arent you powering the +5v off of the computers 5v rail?

  10. #10
    Newbie millc5's Avatar
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    Quote Originally Posted by Will Albers
    and why arent you powering the +5v off of the computers 5v rail?
    After some research here I thought the POL would be better since its at the dash, the PC is in the trunk. That would not matter in this situation however.

    Some one recommended a rectifier diode at the usb hub power in from the POL. Do you think this would work? (Diode type 1n5401)

    Name:  carpcdiag-diode.JPG
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