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  • Power supply question

    Had to put down my old HP printer yesterday.
    As I was preparing the cadaver for disposal I noticed the power supply is rated "32V, 2000ma" output.
    However, it doesn't specify whether that's AC or DC.

    I've never seen AC that low so does that mean the output is DC?
    Len

  • #2
    There are many AC P/S. lower than 32v, but the fact it is a printer with probably stepper motors, it would tend to be DC.
    Max.

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    • #3
      And speaking of that... there are guys who will salvage linear rails and stepper motors out of printers and reuse them. They aren't worth much, but for the guy with nothing they are priceless.
      *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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      • #4
        Originally posted by QSIMDO View Post
        I've never seen AC that low so does that mean the output is DC?
        Low on what, volts or amps? Not sure why either DC or AC couldn't be that low or lower 32V does sound like what might drive a stepper though
        Last edited by Mcgyver; 11-02-2017, 11:38 AM.
        in Toronto Ontario - where are you?

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        • #5
          Originally posted by QSIMDO View Post
          Had to put down my old HP printer yesterday.
          As I was preparing the cadaver for disposal I noticed the power supply is rated "32V, 2000ma" output.
          However, it doesn't specify whether that's AC or DC.

          I've never seen AC that low so does that mean the output is DC?
          Why not test it out? Surely you own a basic multimeter. Also the steppers can be worth a few bucks depending on their size.
          12x16" Delta 3d printer (Built from scratch)
          Logan 825 - work in progress
          My Blog - http://engineerd3d.ddns.net/
          Youtube Channel - https://www.youtube.com/channel/UCVY...view_as=public
          Instagram - https://www.instagram.com/engineerd3d/?hl=en

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          • #6
            It's DC, but with a pictorial symbol of a solid line above a broken line, rather than saying DC.

            No steppers; cheap brushed motors with printed encoder strips/wheels to run as servos.

            There will be a bunch of 400 series stainless ground rods in there.
            Paul Compton
            www.morini-mania.co.uk
            http://www.youtube.com/user/EVguru

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            • #7
              Originally posted by Mcgyver View Post
              32V does sound like what might drive a stepper though
              Quite possible, the power supply for a stepper motor can be ~6x the plate voltage of the stepper, the controller or drive maintains the stepper plate current throughout the rpm range where the inductive reactance increases with RPM.
              Max.

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              • #8
                99.9% sure that it is DC. There is almost zero use of AC in a device like a printer. The PC boards will need DC. The motors will very likely use DC. The print head will use DC. If the PS is AC, then each area of the machine would need it's own power supply with rectifiers, filters, and in some areas, regulators. By distributing one DC Voltage that is cut down to just using regulators in each area.
                Paul A.
                SE Texas

                And if you look REAL close at an analog signal,
                You will find that it has discrete steps.

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                • #9
                  P.S. I always save power supplies. Never know when they might come in handy. Even if I have to cut the plug off.
                  *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

                  Comment


                  • #10
                    Originally posted by EVguru View Post
                    It's DC, but with a pictorial symbol of a solid line above a broken line, rather than saying DC.

                    No steppers; cheap brushed motors with printed encoder strips/wheels to run as servos.

                    There will be a bunch of 400 series stainless ground rods in there.
                    Ahhh, the ancient Egyptian symbol for DC.
                    Oh, hell, I'll strip this to the bone!

                    Also, it's rated 2000ma so that's 2 amps, correct?
                    If I had a 36v motor at 0.8 amps would I fry it?
                    Last edited by QSIMDO; 11-02-2017, 04:00 PM.
                    Len

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                    • #11
                      Originally posted by QSIMDO View Post
                      Ahhh, the ancient Egyptian symbol for DC.
                      Oh, hell, I'll strip this to the bone!

                      Also, it's rated 2000ma so that's 2 amps, correct?
                      If I had a 36v motor at 0.8 amps would I fry it?
                      Nope. As long as the voltage is about right for the motor, which would be fine at 32 volts. The power supply will produce *up to* 2 amps at 32 volts, the motor will draw a bit less than 0.8 amps.

                      -js
                      There are no stupid questions. But there are lots of stupid answers. This is the internet.

                      Location: SF Bay Area

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                      • #12
                        Originally posted by QSIMDO View Post
                        Ahhh, the ancient Egyptian symbol for DC.
                        Oh, hell, I'll strip this to the bone!

                        Also, it's rated 2000ma so that's 2 amps, correct?
                        If I had a 36v motor at 0.8 amps would I fry it?
                        Motors "draw" current according to load, and have a minimum draw at no load. If 32V is OK, you are good.
                        CNC machines only go through the motions

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                        • #13
                          Great, thank you!
                          Len

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                          • #14
                            Originally posted by J Tiers View Post
                            Motors "draw" current according to load, and have a minimum draw at no load. If 32V is OK, you are good.
                            With the exception of stepper motors that draw the motor rated current constantly throughout the rpm/load range, even when stationary, at least with the proper drive.
                            Max.

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                            • #15
                              I seem to recall some drives cut current when not receiving signals.
                              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

                              Comment

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