M2-ATX for auxiliary power supply

**Rick99TAWS6** · 04-24-2008, 10:30 AM

OK, I have got an extra M2-ATX sitting around and considering using it to supply 12V and 5V in the front of the car(puter in the trunk area) to power my screen, dvd/cd-rw usb drive and a usb powered hub - done some searching and just wanna make sure I got it right

Normal power connection to M2-ATX(12V battery, 12V ignition, and ground) then connect pin 14 from the ATX plug to ground, pin 10 for 12V +, pin 15 for 12V -(ground), pin 19 5V +, and pin 15 5V-(ground)

Now does it matter supply wise if I use only pin 19 to supply 5V+ to both the usb drive and hub or would it be better use pin 19 for the drive and 20 for the hub???

TIA
Rick

**ajscomp372** · 04-24-2008, 07:30 PM

Watch out, the ground of +12V is NOT -12V. That would actually be a voltage difference of 24V. Likewise, +5V to -5V would be a 10V difference. Ground of this power supply is earth (0V), so connect your grounds to those pins. As for the hub and drive, they probably use very little current compared to the max output of that pin, so you could probably connect those both to that one pin.

**Rick99TAWS6** · 04-25-2008, 08:49 AM

Thanks, do not think the 15 pin is -12V, I should have made that a little clearer in my post - now thinking I will use pin 17 as the 5V ground and 15 as 12V ground

Seen another post mentioning grounding pin 13 to 14, will I lose the startup/shutdown timings by doing that??

Dont really want to run a wire to hook pin 14 from the front to the puters pin 14, but then again I am getting ready to cover all of the cheap gm plastic(door panels have the infamous firebird cracks starting)................ gonna have to consider that if the grounding of 14 causes it to lost startup/shutdown capabilities

**ajscomp372** · 04-25-2008, 11:55 AM

If you take all of the jumpers off of the M2 ATX and ground pin 13 to pin 14, the M2 ATX will always be on. You might want to consider having your computer, or whatever is doing the startup/shutdown control switching a relay between pins 13 and 14. That way, when your computer comes on, the power supply for your screen and USB devices will come on as well.

**rijk** · 04-26-2008, 11:13 AM

If you use a second battery to power your m2 it will work.

I have an m2 as a standby on a second battery. But you need to connect the green with a black wire (J7), so the m2 thinks there is a mobo attached that wants power (a litle wire on the m2 will do this).
In this way you could even use the jumpers and have it turn on / off by a switched wire.

**Rick99TAWS6** · 04-26-2008, 12:44 PM

Thanks rijk - gonna give that I try, just what I was hoping to do............

**rijk** · 04-27-2008, 04:49 AM

The left is standard m2, the right one has the wire (pencel points towards it).

one thing to think about, the power is switched off at hardoff, not at soft off so jumper on position 1 is probebly what you want (hard off 45 sec).

**danielkh** · 05-07-2008, 02:31 PM

I'm about to do the same with an extra M2, but I don't understand something. If you are just going to run a hub, monitor, etc. with the extra M2, why couldn't you just short the 13 and 14 pin, then hook both main and ignition to the ignition only and accomplish the same things as a relay? Or might this cause issues during startup? Not sure I understand the reason for the "always hot" wire if it's not actually running a PC. Am I missing something?

**rijk** · 05-07-2008, 03:16 PM

Relay? Thats not part of my solution

Wel the problem is when you lose power to your hub, or other powerd usb-device while the mobo is not jet switched off, you can lose a couple of usb-devices. You also want the power on, when the mobo starts (usb). And yes, during start up you wil lose the power on your second m2.

My mobo is also wired to the remot of the alarm, so you wnat it to power on then. My experience is that the m2 only checks the power when starting up with jumper (installed) without the jumper no check. Mij dsx keeps checking the battery, so that one is hooked up to the main battery. The m2 witch i don't trust 100% is hooked up to the second battery.

**danielkh** · 05-07-2008, 06:52 PM

Still not sure it wouldn't work. I will be driving a d-link 7 port powered hub (type B usb, not that mini plug), but it is also non-powered (short distance, low power). The things it will be driving are the touchscreen usb (maybe), an Imon ultrabay, HD radio serial converted to usb, andrea mic, obdii, dvd (#1), and an external usb port that is normally "open". The M2 will be driving the hub, imon ultrabay, hd radio, and dvd.

After the computer starts (something like 3-4 seconds from S3 standby), the usb ports would become active and require greater power. But when the computer goes into standby and during standby, wouldn't the self powered part of the d-link be enough to maintain USB integrity since no data transfer or power draw is occuring?

What I am trying to do is separate the computer into 2 groups. The first group would be the computer itself, along with video, dvd (#2), sound, xm, wireless, bluetooth, gps, scanner, and amplifier control. The second group would be everything mentioned up front. Then a single gold plated 6' USB to connect the front to the back to put it all together.

Since the new computer will have 2 serial ports built in (first serial is used for amp control), the hd radio might move to group 1.