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Thread: SIMcheck power supply question

  1. #1

    Default SIMcheck power supply question

    I just got an original SIMcheck, with manual but without PSU.

    The manual says that it wants 9VDC, but doesn't indicate polarity.

    Would somebody who has one take a look see whether it's +ve or -ve center, please?

  2. Default

    Did you solve this problem? If yes, please, write details.

  3. #3
    Join Date
    Apr 2015
    Austin, Texas


    Most wall warts use center positive to avoid barrel connectors going BANG when touched to a grounded metal surface.

    But to be absolutely sure, you can just open the unit and do some continuity testing, if not just visual testing. The negative connection is going to be connected to a ground plane, at which point you know what positive is.

  4. #4
    Join Date
    Jan 2014
    Western North Carolina, USA


    Negative is not always ground. The best example is your own landline, if you have one, which is positive grounded -48vdc nominal.

    I have an Astronomical camera here with a 12vdc supply with positive grounded and on the outside of the barrell.

    Also, if neither is grounded, but the output is transformer isolated (either at 60hz input or at a few kilohertz in a switcher) then shorting either output to ground is safe. Just don't short the outputs together.
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  5. #5


    Quote Originally Posted by essay View Post
    Did you solve this problem? If yes, please, write details.
    Yes, I did, by giving the manufacturer a call and asking. While later models are positive center, the original SIMcheck uses a negative center.


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