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.
-- bkw On Feb 12, 2018 3:02 PM, "megarat" <mega...@yahoo.com> 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, > CAM >