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minimum suitable voltage for a 5140?

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    minimum suitable voltage for a 5140?

    hi!

    I've acquired a 5140 in bad shape and missing the battery/power supply.

    I've cleaned it up as best i can and I'd like to power it with what I have here. Yes, I've ordered a NOS (hopefully!) 15v 5140 power supply that'll be here in a couple weeks.

    So!

    * can I run it without the batteries installed?
    * what's the minimum voltage I can supply it and have the thing come up?

    I tried a regulated 12v 5A supply but it will just beep once with the boot-up beep, then go dead. I'm guessing power-good isn't very good

    thanks!

    #2
    Originally posted by erikarn View Post
    * what's the minimum voltage I can supply it and have the thing come up?
    That information is in the 5140's technical reference.
    See also, post #4 of the thread at [here].

    Comment


      #3
      It will run without the batteries installed, but it'll be annoying because it'll lose its setup information and make a fuss out of it if you unplug it.

      If you happen to have the original battery pack and are planning to re-cell it please take a lot of pictures of what's inside and what the polarity of the contacts are. I don't have a pack at all; it's been on my list to try making a simple taped-up substitute after I can find suitable thermal fuses to keep it from going nuclear if something goes wrong with charging, but I don't think the service manual has the polarity of the connector documented.
      My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

      Comment


        #4
        Originally posted by modem7 View Post
        That information is in the 5140's technical reference.
        See also, post #4 of the thread at [here].
        Hi,

        Well, mine doesn't really do very much at a regulated 12v or 13.8v.

        Does anyone have schematics? I can see 12/5v power on the power edge connector, but I'm at a loss right now figuring up if the right bits of the board are receiving power and how the power sequencing works.


        -a

        Comment


          #5
          ok, i lie - it's a busted power switch. delicately poking it so it does its momentary thing works.

          now, the display is busted. time to figure that out.

          thanks!


          -

          Comment


            #6
            Originally posted by Eudimorphodon View Post
            It will run without the batteries installed, but it'll be annoying because it'll lose its setup information and make a fuss out of it if you unplug it.

            If you happen to have the original battery pack and are planning to re-cell it please take a lot of pictures of what's inside and what the polarity of the contacts are. I don't have a pack at all; it's been on my list to try making a simple taped-up substitute after I can find suitable thermal fuses to keep it from going nuclear if something goes wrong with charging, but I don't think the service manual has the polarity of the connector documented.
            I don't have the battery pack but i can just go measure the battery pack voltage for you when charging. That'll tell you what it needs to be for wiring.

            I mean, I have some 90C thermal fuses for other reasons but they're likely too high for the NiCDs. My bet is it needs to be something lower like 50C.

            Comment


              #7
              And my 5140 works fine save a dead screen, and replacement 640x200 LCDs from that era are like $300 a pop minimum. So, I may have to go learn Verilog and make a bloody scan converter to VGA. The timing is a bit oddball, 50Hz refresh rate @ 640x200. I'm hoping that doubling it to 640x400 and adding the needed padding for VGA will fall within spec of le olde LCD monitors so i don't need to do it a /frame/ at a time...

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