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Dell SX260 and SX270 power supply solution

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  • Dell SX260 and SX270 power supply solution

    Hi all,

    Since finishing my SX260 install last week I've had one or two people asking exactly how I wired up the power.
    Hopefully this thread will help anyone else similarly stuck:

    Firstly, I know that one or two people have wired their SX's directly to the battery, but I did not feel happy doing this at all.
    Frying a PC is a lot more expensive than putting in a regulated power supply...

    I used a DSX12VD DC-DC power supply, but that was complete overkill as I didn't use any of the fancy switching facilities it offered.
    Given a second chance I would use a DSX12V because it's probably cheaper

    This PSU is capable of handling 12A constant, 15A peak.
    The Dell pulls 7-8A constant, peaking to 12A on startup so the PSU is capable of running it no problem.

    Mine went in a project box with a fan like this (ignore the grey wire)

    OK, lets do the wiring at the PC end:

    Cut the cable between your old Dell AC PSU and the PC connector.
    I cut mine about 6" from the PSU to give me plenty of cable in the car.

    The SDSX12V will come with a 4-wire fly-lead connected to a molex connector.
    These wires are 2 x yellow (12V), 2 x black (Gnd).
    Solder the lead you’ve just cut to the ends of that like this:
    Red to one Yellow
    Brown to the other Yellow
    Black to Black
    White to Black
    Also, solder the screen to black.
    Fold the Green and Yellow wires back against the cable and tape them up.
    Tape each join up individually, then tape the whole lot together.

    That’s the PSU output to the PC taken care of, now lets look at the input to the PSU.

    Now you could wire the input straight to the battery – but how would you switch it on & off?
    Ever seen the size of a battery isolator switch? That’s the sort of thing you’d need to handle the current. So forget that.

    Parts you’ll need:
    15A or higher rated twin core cable (Red & Black?)– enough to reach from your PSU to the battery.
    A 15A fuse. (Yes, I know the PSU also has one, but we’re going to be running a cable from the battery into the cab so we’d better protect it at the battery end too.)
    A relay capable of handling 15A. I used a 30A one I happened to have lying around.
    Some lighter single core wire – enough to reach from the PSU to where you want your switch plus onwards to a 12V supply.
    A switch that you can mount in the dash or wherever you want it.
    A short length of cable for Gnd.

    I shouldn't need to tell you, but CONNECT THE BATTERY LAST!!

    Firstly, the heavy duty cable:
    PSU 12V IN to one leg of the relay main link using a short section of the heavy duty cable (Red).
    Connect the rest of the Red cable to the other side of the relay link. It can then go through the firewall into the engine bay.
    PSU Gnd can safely go all the way to the battery using the Black core of the same cable.

    Now the light cable:
    A short section from PSU Acc to one side of the relay switch.
    Another length of this cable can now go to your dash switch from the same relay pin.
    Then a short section to go from the other side of the dash switch to a 12V supply in the dash (the radio feed?).

    Lastly, the short length of earth cable from PSU Gnd to the remaining pin on the switch side of the relay.

    You should hopefully have something like this:

    OK, time for a test.
    Remember that old Dell AC PSU? Put a connector block on the remaining 6” of cable you left (you didn’t cut it too short did you?)
    Red and Brown – join together to form the 12V In.
    Black, White and Green ans screen – join together to give the Gnd.
    (Green needs to be joined to earth to fool the PSU into thinking there’s a PC on the end.)
    Tape the Yellow up or join it in to earth – it’s not used anywhere.

    Join the connector block to the heavy duty cable and it will simulate the car battery.
    Also wire the free end of the switch to the PSU 12V to feed the power there.
    No need to connect the PC yet – the DSX12V has an LED to tell if it’s giving power.
    When you flip the dash switch you should hear a click from the relay and the LED will go on.

    If all’s well, connect the PC and retest. The SX260 and 270’s have a function in the BIOS which switches the PC on when power is applied. Very handy.

    When you’re satisfied that all’s well, go ahead and fit the PSU into the car.

    If you haven’t already done so, now’s the time to fit the 15A fuse in the heavy duty Red cable fairly near the battery.
    If you put it somewhere accessible, it can also act as a valet switch when you leave your car at a garage etc.

    Hope all this helps someone.


    PS. Working of a relay for those that don't know:

    When power is applied to 12V (switch) it pulls the internal switch between Main 12V IN and Main 12V OUT closed, this making the full circuit to the PSU.
    The advantage of using this is that you only need a small switch as the current on that side of the relay is very small.


  • #2
    this is spectacular, thank you!


    • #3
      Is there any way I can connect DSX12V to dell sx260 as I dont have the power cable.

      Is there any way I can connect DSX12V to dell sx260 as I dont have the power cable.

      There are six inputs in the power connector, can i directly remove it and connect it to the DSX12V.

      Also how much does DSX12V costs?

      And btw, the explanation above is amazing.


      • #4
        Originally posted by justboomit View Post
        Is there any way I can connect DSX12V to dell sx260 as I dont have the power cable.

        There are six inputs in the power connector, can i directly remove it and connect it to the DSX12V.

        Also how much does DSX12V costs?

        And btw, the explanation above is amazing.
        How do you envisage connecting them without the connector? If you've opened up the Dell you'll see it'd be very difficult to wire in directly. It would also ruin the PC for future reuse.
        Your best bet is to get a PSU from Fleabay. About a tenner IIRC.

        As for the DSX12V, you need to email them:

        And thanks.


        • #5
          So wait, all you need is the dsx12v and the square plug that goes into the dell pc? You don't need the big power brick?


          • #6
            PM'd (and copied in below for all to benefit from if needed). But yes, that's right.

            Originally posted by MAZDABOY
            Hey man, I've read a lot of your posts about your car-pc. How well is it working out? I need some help if you could.
            I am going to use the following:
            panasonic 7" in-dash
            alpine cda-7995
            dell sx260 pc

            I'm looking into the dsx12v for a regulator right now, woudl that be everyhing I need? (if i changed mb's down teh line would this still work?)

            Does it come with startup/shutdown features?

            Basically, how I want things to work are. I want the pc to boot up after I start the car (on it's own & delayed for a few seconds). I want it to shut down after the key is removed. So if I turn off the car but leave the key on, the pc will stay on.
            Then I want to have a complete kill switch in my glove box to where if it's off the pc will not go on at all. (for short drives or just to turn the key on to play with a radio setting for a second or whatever)
            Where would the kill switch go, on teh relay? Ground side?
            Would the dsx12v suit all my needs? Also, how do you like the gps? I have the same antenna, where can I find the software?

            I really appreciate the help. I would like to order the power supply asap and try to get this whole project done in less than 2 weeks.
            Sounds like the DSX12VD would be better for you than the DSX12V to be honest.

            The 12V is a straight 12v-12v regulator whereas the 12VD has the startup and shutdown features you want. To get the startup and shutdown you will need to solder 2 small wires to the PC on/off switch so it can provide the pulses to the PSU.
            Check the grey wires in the first pic. They should go to the PC on/off switch but I decided not to use them.

            It'll be fine on other mobos too.

            If you want the supply to remain on with the key turned, remember to take the power for the relay from the cars Ign circuit rather than straight from the battery. The kill switch can go there too.
            The main 12v feed through the relay to the PSU can come straight from the battery (via a fuse obviously).

            So wire the power the same as the second pic above. The yellow feed to the relay would be from your Ign circuit.

            And the Carputer's still going great thanks. I settled on the cheapest commercial version of Centrafuse in the end because I already had Destinator to go with it. David's still got a few more things to do but hopefully there'll be an update with these enhancements in soon.

            GPS and wireless work great too apart from the GPS doesn't like coming back from hibernation all the time. That's mostly a Dell problem I think though - it's fine from a cold boot.


            • #7
              Originally posted by ivanmx6 View Post
              The SX260 and 270ís have a function in the BIOS which switches the PC on when power is applied. Very handy.
              What option in BIOS is it? I have 270n and don't remember seeing it.
              So, just to be clear - if power option in bios is set I won't have to run wires to the front panel power switch?

              Also, that GPS/hibernation issues seems to happen to me as well. Can't really find a solid answer for it though. I've seen people blame RoadRunner, Dell etc.
              There was a post few days ago (I can't find it) where soemone claimed that Xport fixed that issue for good. It didn't work for me.


              • #8
                It's a setting called AC Power Recovery Jay.

                As for the wires, you will need to run them if you want to power off the PC remotely.

                Dell themselves recognised the hibernation issue and posted a patch. Unfortunately it wasn't 100% successful.
                (I'm using XPort too)


                • #9
                  Originally posted by ivanmx6 View Post
                  It's a setting called AC Power Recovery Jay.
                  (I'm using XPort too)
                  Care to share configuration for Xport? I know it's very simple but I don't see any improvement while it's running.


                  • #10
                    GPS is physically on Com3 (USB) and I've got XPort mapped to mirror the signal on ports 5, 6 & 9. Set up as NMEA.

                    5 is for CF/Destinator, 6 is for GatsoHunter and 9 is spare at the moment, was used for RoadRunner front screen dials.


                    • #11
                      Something must've been corrupted with the one I was using.
                      Deleted the old one, re-downloaded it and all is good. No more hibernation problems


                      • #12

                        Great post, just what i need, however how did you power your screen, from live ignition or from the psu



                        • #13

                          I have a question, why did you use a relay when the psu acc can be connected to a switched power line from the car, doesn't this signal turn the psu on/off?



                          • #14
                            I think i've answered my own question, the relay is there to allow for isolation of the carpc via the kill switch, if i take the feed from the acc on the ignition AND use the startup/shutdown facilities it will turn on and off with the ignition, if i'm going on short journeys or just switching the ign on and off i can flick the switch to isolate the carpc.



                            • #15
                              hi Me again!

                              Decided to re-read this thread and saw the post re connecting the grey wire, can you confirm which pins you connected them to on the psu, was it G1 and G2 also if i use the advanced features when i remove the ignition switch, does the psu maintain power for a pre determined time (pot switch) then switch off the PC AND the feed to the PSU, i'm worried about battery draining.