Yes the center pin is negative. Same is true for most of the related
accessories like the tape drives ctr-41, ctr-80, ccr-81, ccr-82, ccr-83,
the tpdd & tpdd2 disk drives, trp-100 printer, etc. They all take 6vdc,
center negative, same 5.5x2.1mm barrel plug.


On Feb 12, 2018 3:02 PM, "megarat" <> wrote:

> Greetings again, folks.  Thanks for the feedback you gave me about digital
> audio recorders, it was very helpful.  I hope you don't mind another
> hopefully quick question.
> Some time ago I built an off-board power supply that could power my M100
> with 4 D-cell batteries by connecting them to the AC adaptor port.  (An
> idea suggested on this list.)  I had never actually tested it, and in
> hindsight, I'm not sure if I got the polarity correct when I wired the
> battery pack to the barrel connector.
> According to one of my documents, the official Tandy AC adaptor is listed
> as "center-negative" or "center-minus".  Does this mean that the terminal
> in the middle of the barrel should be wired to the negative wire on the
> battery pack?
> And to further indulge my curiosity, what would happen if I tried to use
> such a D-cell-based power supply if the polarity were reversed?
> Thanks again,

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