M2-ATX Power Switch Problems

**cobase** · 02-01-2008, 04:56 PM

I haven't reinstalled mine yet. When I mailed it to them, the J8 resistance was 0 Ohm, and when I got it back, it's Open. So far, so good. How do I check which way it's supposed to be plugged in?
Is one of the pins on the motherboard shorted to ground, and the other +5V or so?
How do I know which is the grounded one on the M2?

**cobase** · 02-05-2008, 11:10 AM

Ok, so figuring out which pin on the motherboard is the right one is easy. Both pins are small resistances to ground (one is 6 Ohm, the other 9 Ohm), but only one (call it "signal") boots the computer when its shorted to chassis. The other does nothing, so call it "ground." Fine, good.

Now, on the M2-ATX, the connector on the cable is asymmetric: the bottom J8 pin goes to RED, the top pin to BLACK. Otherwise the pins are identical: Both are 3 Ohms to ground in forward bias and Open to ground in reverse (e.g. a diode), and Open to each other in both directions. So I assume the top J8 pin (RED wire) goes to the signal pin on the motherboard, and the other J8 pin (bottom, black wire) goes to the ground pin on the motherboard. I think only this way makes sense though I'd like some confirmation from mini-box or someone else who knows more than I do.

I mean I could hook the thing up, turn on the 12V to the ACC signal and watch what the M2-ATX J8 pins do with a voltmeter... but that's such a pain to set up

I guess I'll do it anyway just to be dead-certian.

**Syx** · 02-08-2008, 08:15 AM

Hey cobase, did you get everything sorted out in the end?

**cobase** · 02-08-2008, 06:53 PM

Uh... yes, for a few glorious minutes before I put the case cover on wrong and shorted out the M2-ATX, fried it and killed the motherboard.
Ah, the smell of fried circuitry in the morning.
Second M2-ATX on its way.... ou$h.

**nobb** · 02-08-2008, 10:14 PM

What pins did you short on the M2-ATX which caused your motherboard to fry? All these stories of M2-ATXs killing motherboards makes me feel nervous...

**Syx** · 02-09-2008, 07:03 PM

That's unfortunate! Fingers crossed for the next one

**cobase** · 02-09-2008, 10:47 PM

Originally Posted by nobb

What pins did you short on the M2-ATX which caused your motherboard to fry? All these stories of M2-ATXs killing motherboards makes me feel nervous...

No, this wasn't a delicate short, this was a 6" long blade of metal pushed and slid against the surface of the board, shorting many components along its path. Kind of like saying I accidentally dropped a sledgehammer on it.

My bad.

**wwiifanatic** · 03-12-2008, 02:32 AM

Mine appears to have the same problem....

Voltage on J8 is constant, motherboard turns on...turns right back off after a few seconds.

**Doogle** · 10-20-2008, 08:55 AM

I'm beginning to think my M2-ATX is causing the problems with my carPC too. it works fine when plugged into a normal PC ATX power supply indoors but when I put it in the car it will boot fine once or twice and then will say there is no HDD installed and then wont boot at all!
Though it could also be the motherboard on it's way out too as it's done it's fair share of sparking and smoldering while plugging in or removing USB cables!!

**Syx** · 10-20-2008, 01:20 PM

My second one gave up on me after a few months, for seemingly no reason at all it refused to operate. I think the device is a little bit temperamental!