# m4-atx start pulse not working



## Orion525iT (Mar 6, 2011)

I am kinda getting a bit frustrated with this thing. General lack of documentation and troubleshooting information is an issue. I did a search at mp3, and really didn't find a solution. 

So the psu seems to work. But I can only get the computer to start by jumping the power header on the motherboard. The psu is supposed to send a on pulse, but it doesn't work.

I have no idea how to trouble shoot it. I really don't know what it does or how the "pulse" works. I figured it was just a switch that closed for a moment just like a manual power button. But when I measured resistance from the power lead of the psu, it did not change during the pulse phase. Voltage across the same leads only changed microscopically.

Anybody trouble shoot these things?


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## audiovibe (Nov 16, 2007)

There should be a jumper wire that goes from the M4 to the motherboard. This is what will tell the motherboard to turn on. I cant remember what pins it plugs into but it will be on to 10 pin black socket next to the dip switches.


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## Orion525iT (Mar 6, 2011)

audiovibe said:


> There should be a jumper wire that goes from the M4 to the motherboard. This is what will tell the motherboard to turn on. I cant remember what pins it plugs into but it will be on to 10 pin black socket next to the dip switches.


I know. Not the issue, everything is connected properly.


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## diy.phil (May 23, 2011)

I briefly played with a few M2-ATX version for somebody's scary/prototype/driverless project. Since you mentioned it's wired correct including the power on-off header on the mainboard... check the voltage at the Ignition SW terminal (input connector). Be sure the voltage/signal here follows the key or start-button sequence. Also check the mode.... be sure it's P1, P2, P-something (not P0). I just saw the M4-ATX manual and there's also a JP1 factory reset that you may want to try. If all those are correct and it still doesn't work, maybe call for an RMA/swap. Good luck!


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## Orion525iT (Mar 6, 2011)

It will do something, in that the fans on the mb will twitch for half a second a the time that the psu is supposed to send the on pulse, but it never gets to post. I tried different p (x) settings, and it doesn't seem matter.


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## diy.phil (May 23, 2011)

Difficult to diagnose over the internet and may be a compatibility issue. Maybe ask the M4-ATX company how wide is the pulse to the switch/header. Also ask the mainboard company how wide a minimum this pulse/trigger needs to be (in case there is a compatibility issue between both of them here). 

But if the fan twitches for a moment it sounds like a power problem (or recheck the 4-wire 12V-ATX power, if any, for the processor is securely plugged in). Also unplug all peripherals/drives/boards to see if it posts (no power brownout at start, just a test boot with the basic mainboard, memory and processor/fan). But then again if you can manually switch/toggle it to start then maybe it shouldn't be this power problem.


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## BlueGhost (Jul 28, 2014)

I'm not sure about the M4, but on my M2 the polarity mattered on the power button jumper. One way it would hang and cause the pc start booting then power back off. When I flipped the jumper at the motherboard it would boot without any problems.


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## Orion525iT (Mar 6, 2011)

diy.phil said:


> Difficult to diagnose over the internet and may be a compatibility issue. Maybe ask the M4-ATX company how wide is the pulse to the switch/header. Also ask the mainboard company how wide a minimum this pulse/trigger needs to be (in case there is a compatibility issue between both of them here).
> 
> But if the fan twitches for a moment it sounds like a power problem (or recheck the 4-wire 12V-ATX power, if any, for the processor is securely plugged in). Also unplug all peripherals/drives/boards to see if it posts (no power brownout at start, just a test boot with the basic mainboard, memory and processor/fan). But then again if you can manually switch/toggle it to start then maybe it shouldn't be this power problem.


There are changes you can make that alters the pulse time and length. Fiddling with those did no good. It is also entirely possible that it is a bios issue too, that something is not set quite right there. It maybe a compatibility issue that cannot be remedied, I suppose. BTW I have since found that mini-box (the manufacturer) is notoriously bad about support. 

All peripherals are integrated, with a single SSD hard drive which pulls almost no current. Again, it works perfectly as normal power supply by using a start button. It even powers the usb ports in the off state, as the motherboard is designed to do. Heck, I am also powering my Minidsp 2x8 off of one of the 5v rails. So the power supply does as it should in all other ways, just not the on pulse. It does attempt the on pulse; there is a little led on the psu that blinks rapidly during this stage, but no post, just a quick twitch of the fans. 



BlueGhost said:


> I'm not sure about the M4, but on my M2 the polarity mattered on the power button jumper. One way it would hang and cause the pc start booting then power back off. When I flipped the jumper at the motherboard it would boot without any problems.


Pretty sure I tried it both ways. But I suppose its worth a shot again.


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