M2-atx Override Switch

**funkyphil** · 05-01-2008, 05:11 PM

Need Help understanding how to override my PSU so I can turn off my IGN and still keep my pc running. I have searched and seen a few drawings but I am not very good at understanding how it all reads. My thinkings are this,

1. one wire from the switch to the IGN of the psu IGN
2. other wire from the switch to the "always on power"

Does this seem some what correct? Or am I way off?

I have attached my version of a diagram, feel free to laugh as well! I am far from an artist! Hope if any it gives you some kind of Idea of what i am thinking.

Thanks alot Phil

**2k1Toaster** · 05-01-2008, 06:17 PM

Yup, just like that.

Of course if you get an ON-OFF-ON switch, then if you leave the switch in the middle, the PC will not turn on with the ignition, good for when you just need to roll your windows up or something./

**funkyphil** · 05-01-2008, 06:29 PM

cool thanks alot, could you help explain how I would wire the three pos switch? where does the thrid wire from the switch go? sorry don't mean to sound dumb just not sure and don't want to burn out either my psu or mb.

Thanks alot 2k1toaster! You are the man!

**2k1Toaster** · 05-01-2008, 06:36 PM

ON --- Constant +12v
OFF -- To IGN of M2-ATX
ON --- Switched +12v

**funkyphil** · 05-01-2008, 06:45 PM

2k1toaster

could you have a look at this picture, they are saying there is an optional on/off switch is this switch the same as what I am trying to do? Is it built into the psu already? Or is this for something different?

Again many thanks
Phil

**2k1Toaster** · 05-01-2008, 07:16 PM

That is not actually and "on/off switch". It is a momentary pushbutton (like you would find on your computer case) for manual control that way.

If the M2 is on (regardless of computer state) then the momentary button on J9 will turn the computer on and off depending on how it is setup in windows (sleep/wake, hibernate/resume, full on/full off) as well as the M2's automatic on and off from the PIC timers.

The switch that you described in the beginning goes to control the M2. Has nothing to do with the PC. If the M2 sees no power on the IGN line, it never wakes up, meaning the computer doesnt get power/wake up. If the M2 sees the car's switched 12v (default wiring), then the M2 is on when the car is on, and M2 is off when the car is off. This then is passed to the computer which becomes on when the car is on and off when the car is off. If the M2 gets constant 12v, then the M2 is always on. So the computer will turn on automatically with the M2 when you wire it in the car, and will stay on until the battery dies. The computer will be sent 1 startup pulse when you connect the M2 to the car's wiring, and will never be told to shutoff.

So the best method is use a switch. That way you can select these modes when you want.

Need to roll up the windows? Then flip the switch to the centre so the M2 gets no juice on the IGN line. Then turn on the car roll up the windows. Computer never boots.

Need to get gas, and passenger wants to keep using the PC? Then flip the switch to constant +12v. When you turn the car off, the M2 has no idea you did since it now gets 12v no matter what until the battery dies. But usually a fill up takes less time than to drain your battery unless you drive a Daewoo and are stupid enough to put in a dual Xeon setup or something.

So for normal operation leave it on the ignition area, and the M2 goes the way it was meant to.

**greenman100** · 05-01-2008, 07:35 PM

Originally Posted by funkyphil

Need Help understanding how to override my PSU so I can turn off my IGN and still keep my pc running. I have searched and seen a few drawings but I am not very good at understanding how it all reads. My thinkings are this,

1. one wire from the switch to the IGN of the psu IGN
2. other wire from the switch to the "always on power"

Does this seem some what correct? Or am I way off?

I have attached my version of a diagram, feel free to laugh as well! I am far from an artist! Hope if any it gives you some kind of Idea of what i am thinking.

Thanks alot Phil

your diagram needs a diode after the "IGN" to keep your switch from backfeeding all your other electronics

**2k1Toaster** · 05-01-2008, 07:37 PM

Originally Posted by greenman100

your diagram needs a diode after the "IGN" to keep your switch from backfeeding all your other electronics

if you do it like you wired it.

I thought you had a 3rd wire going from the switch.

If you do it the way I have explained above, you dont need the diode. Just dont feed constant 12v into your switched.

**funkyphil** · 05-01-2008, 10:51 PM

hey guys, can someone be a pal and draw me up a pretty dumbbed down version of how I need to do this? Kinda like the one I drew, cus now we are talking about adding a diode and I don't know where to install that. Or yet even better what kind of diode to even buy. Is there a diode size i need to keep this wiring safe?

Thanks again for all your help, and 2K1Toaster thank you so much for all your time, and replys. Means alot and many thanks to you and everyone who has helpped!

Phil