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what would change the GND of my m2-atx to +12v???

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  • what would change the GND of my m2-atx to +12v???

    This is what i get for tryin to clean up my wiring mess!!!

    i hooked my m2 back up the same way it was wired previously in my car and for some reason its shorting because the ground is reporting +12v!!! i tested this by hooking up my multimeter... each wire acts as normal except the ground (on J4 as its supposed to be). What the heck gives???
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  • #2
    well as probable as it sounds, a short.

    Make sure you didnt have a blonde moment somewhere and cross the wires. Also is the ground constant 12v, or switched?`
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    • #3
      How are you measuring that the ground is +12V? Measurements are from a reference point, which is usually the ground. Your ground is +12V above what point?
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      Gen 2: Pentium M 1.6GHz - ITX - 2006
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      Gen 4: (coming soon: Core2 Duo - 3.5" SBC - 2009)
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      • #4
        Make sure the M2-atx is not sitting on a metal surface, the solder underneath it will cause it to short.

        I blew my fuse doing that

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        • #5
          Originally posted by 2k1Toaster View Post
          well as probable as it sounds, a short.

          Make sure you didnt have a blonde moment somewhere and cross the wires. Also is the ground constant 12v, or switched?`
          no i never crossed the wires once. And the ground is constant 12v... as long as either of the other two pins (constant and remote) are receiving 12v the ground reports 12v.

          Originally posted by psyrex View Post
          How are you measuring that the ground is +12V? Measurements are from a reference point, which is usually the ground. Your ground is +12V above what point?
          when i say +12V i mean 12 volts, not 0 volts, not -12v like when u reverse polarity on the multimeter. I hook the positive side of the meter to the GROUND pin on the m2 and the negative side to the battery ground... the meter goes up to 12volts.

          Originally posted by dom00 View Post
          Make sure the M2-atx is not sitting on a metal surface, the solder underneath it will cause it to short.

          I blew my fuse doing that

          i never had that problem in my last case but the new case isnt constructed out of metal so that wouldnt be the problem. My fuse never blew when i attempted to connect the wires as they should be... there was just an electric charge at the connection point of the constant wire to the m2. No pops or smoke came from the unit itself
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          • #6
            If you're not blowing any fuses or releasing magic smoke then check for continuity between the M2 ground point and your ground test point. With an open circuit, the voltage drop across your high impedance meter would match the supply voltage.
            2004 4runner

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            • #7
              two potential answers

              1) you have a defective unit (either shipped that way or you broke it)

              2) you did not measure the voltage correctly
              TruckinMP3
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              • #8
                Another possibility: Your M2 ground isn't actually connected to the ground of the battery. There might be a disconnect somewhere.
                Gen 1: Pentium 3 1GHz - ATX - 2005
                Gen 2: Pentium M 1.6GHz - ITX - 2006
                Gen 3: Pentium M 2.0GHz - 5.25" SBC - 2007
                Gen 4: (coming soon: Core2 Duo - 3.5" SBC - 2009)
                ...it never ends

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                • #9
                  Originally posted by rando View Post
                  If you're not blowing any fuses or releasing magic smoke then check for continuity between the M2 ground point and your ground test point. With an open circuit, the voltage drop across your high impedance meter would match the supply voltage.

                  I'll have to try that when i get home.

                  Originally posted by TruckinMP3 View Post
                  two potential answers

                  1) you have a defective unit (either shipped that way or you broke it)

                  2) you did not measure the voltage correctly.
                  I know i've tested the voltage correctly... i've been doin car audio installs for 12 years. The unit might have been damaged somehow but i dunno how.. its been installed for over a year and working fine, then i just took it out over the weekend.. reinstalled it the same way it was before just a different case and boom.. problems. I also have an opus POL and a carnetix 5v and both of those work fine.

                  Originally posted by psyrex View Post
                  Another possibility: Your M2 ground isn't actually connected to the ground of the battery. There might be a disconnect somewhere.
                  its definitely connected to the ground of the battery.. i took my auxilary battery out of the car and did a simple test hooking up only the three wires needed to power the psu... constant and remote were connected to +, then i tried to connect ground to - but same prob i had in the car... BZZZZZZZ as if its wired incorrectly. I guess the psu is just fried... damn shame!
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                  • #10
                    Send it back to get fixed.

                    Maybe warranty maybe not. That is the next step.
                    TruckinMP3
                    D201GLY2, DC-DC power, 3.5 inch SATA

                    Yes, you should search... and Yes, It has been covered before!

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                    • #11
                      It definately sounds like you fried a chip then. When a regulator blows, it may sometimes just spew out what it is being fed. Not regulating. So basically a short circuit inside one of your chips. Any of them look burnt, or when you run it get really really hot?
                      Fusion Brain Version 6 Released!
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                      30 Digital Outputs -- Directly drive a relay
                      15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
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                      • #12
                        Originally posted by Sonicxtacy02 View Post
                        its definitely connected to the ground of the battery.. i took my auxilary battery out of the car and did a simple test hooking up only the three wires needed to power the psu... constant and remote were connected to +, then i tried to connect ground to - but same prob i had in the car... BZZZZZZZ as if its wired incorrectly. I guess the psu is just fried... damn shame!
                        Sounds like the PSU has a problem but something about this scenario is still troubling. If in the direct connect scenario above, the M2 ground point is measuring at the supply voltage, then you'd be dropping 12 volts over the ground wire. Assuming it's on the order of 1/10th of an ohm you'd be dumping 120A plus through that circuit. Unless you're using very large gauge wire, the wire itself should get fairly hot and release some smoke. Moreover the short-circuit path on the M2 itself should immediately begin smoking. Also, the act of connecting this circuit would cause a fairly sizeable spark (and likely shock).
                        2004 4runner

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                        • #13
                          Maybe I'm just stuck in a rut, but I'm still confused at the ground part. You're saying there's a 12V drop from the ground of the M2 to the ground of the battery, and there's wires connecting it the whole way? Meaning there's a 12V drop over just wires? That kinda raises alarms in my head.

                          wires mean low resistance. 12volts over low resistance is high amperage, high power. If there's no current running from a 12v drop, then there's high resistance, like a break in the wires? Am I just off base here?

                          edit: typed too long, beat by rando.
                          Gen 1: Pentium 3 1GHz - ATX - 2005
                          Gen 2: Pentium M 1.6GHz - ITX - 2006
                          Gen 3: Pentium M 2.0GHz - 5.25" SBC - 2007
                          Gen 4: (coming soon: Core2 Duo - 3.5" SBC - 2009)
                          ...it never ends

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