How do polarity and amperage work on a barrel DC jack?

Wayne February 20, 2015
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Polarity on the power plug for the ScaleoView T17-1 monitors . I want to know what the polarity on the DC power input plug is.

Specifically, I’d like to know the polarities (+ or -) of both the outside ring and the inner pin on a barrel DC jack.

Also I have found an adapter that is 19 volts and 4.5 amps, but the monitor is 19v and 2.6 amps. I have been told that that a increase of 0.5 amps won’t damage the monitor but an almost 2 amp increase will damage monitor. Is this right?

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  1. Oron J
    February 21, 2015 at 12:07 pm

    As Jan says, most Fujitsu products have the (+) on the central pin, but I can't find any definitive statement or picture regarding your particular monitor, sorry.

    As for power, any power supply with 19V and 2.6A or more would be fine and would not damage your monitor (even 20A, as mentioned by Jan would be OK, although it would probably be huge and waste electricity!).

    I've done a quick search, and you can get PSUs for this monitor on Amazon and eBay. This may be your safest bet.

  2. Jan F.
    February 20, 2015 at 10:42 pm

    Since these plugs are not standardized and may vary even from model to model of the same vendor the polarity should be (generally is) printed on the label of the power adapter. I believe Fujitsu usually uses positive polarity so the inner side of the plug respectively the pin of the socket would be positive and the outer negative.

    No, it should not damage your monitor.
    The important part for the DC adapter is the voltage. If the voltage provided is too low your device will not work or not work properly. If the voltage is too high your device will most likely be damaged.
    The current however is "on demand" or "pulled". If your monitor is in standby it will pull a fraction of those 2.6 amps wherein when it is operating it will use op to those 2.6 ampere. Don't get me wrong - you should probably not hook up a 19V / 20A adapter to your device but whether it has 2.6, 3 or 4.5 amps shouldn't make much of a difference as long as it can provide at least those 2.6 ampere.

  3. ha14
    February 20, 2015 at 9:09 pm