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 mpegbox.com 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
http://www.mpegbox.com/products.html
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.
YMMV.
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.
Regards,
Ken
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.
Cheers.
Is there any way I can connect DSX12V to dell sx260 as I dont have the power cable.
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