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Polarity Lesson: $200. HA Education: Priceless.

Posted by IVB on May 16, 2006

Here’s hoping I didn’t just spend $200 teaching myself about polarity, or more specifically, about what happens when you roll the dice.

My security camera server setup was going ludicrously smoothly. The server build and kodicom card install took all of an hour. That should have been my first clue. I finally unpacked the security camera and universal power adapter got from Tech-home months ago, looked at it, realized the documentation didn’t state what the polarity should be on the power adapter. Spent some time googling, couldn’t figure it out, so I figured, what-the-heck, i’m not going to figure this out via osmosis, so I may as well try one.

Got it all plugged in, no image on the screen. Hmmm. Wonder what it could be. I jiggled all the wires, no love.

I then looked over at the wallwart, and said to myself “Hey – why isn’t that green LED indicating power on anymore?”. I took it out of the wall.

Oh my was it hot. Real hot. Really really hot. Not burning hot, but hot. Much hotter than power supplies are supposed to be. Did I mention it was hot?

Hey – reversing polarity may not be a good idea…

Anyhow, Radio Shack is closed now, but I’ll swing by tomorrow and pick up another universal power supply.

And hope like heck that I only fried the $25 power supply, and not the $140 security camera.


4 Responses to “Polarity Lesson: $200. HA Education: Priceless.”

  1. Jay said

    If the PS was hot, that means the current draw was greater than it should have been (maybe a short circuit)? Maybe (if you are lucky) a reverse polarity crowbar circuit that shunts the current to ground.
    When you state that the camera didn’t state the polarity of the PS, I’m having a hard time understanding. Does this PS just power the camera? Is the wallwart DC or AC out? What’s the power rating listed on the wallwart? Maybe pictures of the camera leads would help?


  2. IVB said

    Thanks for reading about my lament, and any thoughts or education you can give me. God knows I need it.

    The power supply is a universal type, with a variety of connection adapters that come with it. It didn’t come with the camera, rather was sold seperately. It has a variety of voltage settings, from 3V-12V DC. The camera calls for 12V DC, so that’s what I set it to.

    What I didn’t understand until last night was that the DC connector could either be center positive or center negative. And, the camera didn’t state which one, and being the idiot that I am I forgot that DC stands for “Direct Current”, which really means you care heavily about the pos vs neg, so I went ahead and tried one.

    On the token upside, I did just get notified by the retailer I got it from (tech-home.com) that the camera is center positive. With any luck, the current did get sent to ground and my camera is still operable.

    I’ll take pictures tonight and post.

  3. Jay said

    Double check the the current requirement of the camera with the rated output of the transformer. 12V @ (X)A is what you will see stamped into the plastic on the universal transformer.

    On the camera/device itself, you should see a stamping in the plastic near the DC connector that would signify the polarity too. The standard is center positive (think RCA and COAX connectors), but for some reason, Japanese manufacturers tend to be the opposite.


  4. IVB said

    Thanks for the tips. I’m currently out of town, but will make sure to check it upon my return.

    I’ll be sure to post pics of the setup once i’ve got it up & running.

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