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Thread: Strange M2 issue.

  1. #1
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    Strange M2 issue.

    I've got a weird issue with the M2. Just fitted all my parts together and wired it all up. Plugged in an external DC 12V supply. The red and white wires (J1 and J3) I connected together then to +ve and the black wire (J4) to -ve. J8 is connected to the MB switch. When I switch the supply on, all the fans start and then power off, then up then off. Then they'll run for a few seconds and then off again. If I remove the 4pin 12V supply (M2 - MB) the fans power and the system stays on. If I plug the 12V in again, it starts 'pulsing' again. I thought maybe the 12V supply from the M2 was faulty so connected it to the spare supply. Same thing. To make sure the MB was OK, I connected it to another PSU directly to the MB and it all works OK.

    Searching on here I've read that the on/off switch can be in the on position but if I leave that wire off and manually start the PC it still 'pulses' on/off.

    I know some people loathe the M2 and others like it. However, troubleshooting information for the M2 isn't easy to come by so I was wondering if there is anything else I can try.

  2. #2
    High Voltage blk02si's Avatar
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    What motherboard are you running?

    What is the amperage your external 12 volt DC supply is capable of running?
    Build Things, it keeps your brain busy.

    AutoPC v1 (Retired) - AutoPC v2 (in progress) - www.shocknet.us

  3. #3
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    J&W Minix Mini-itx AMD2 motherboard
    AMD Athlon™ 64 X2 Dual-Core 5200+ @65W TDP
    Silverstone NT07 super slimline CPU cooler
    M2-ATX 160W PSU
    1GB DDR2 SODIMM
    Western Digital Scorpio Blue SATA 320GB

    Power supply is 5amps and 12V DC. Haven't been able to find my multimeter so will buy one this morning and test outputs especially the on/off switch. I've even tried reversing the cable for the switch. I only have a few days left to return it so I need to get a wriggle on.

    If it was a constant on signal, surely the board would power up for more than a second before it turns off and then up again. What would happen if the wires to the 12V supply to the CPU were reversed? (The cable is an Ebay special.)

  4. #4
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    Quote Originally Posted by blk02si View Post
    What motherboard are you running?

    What is the amperage your external 12 volt DC supply is capable of running?
    Replied but don't know where the post went.

    Specs...

    J&W Minix Mini-itx AMD2 motherboard
    AMD Athlon™ 64 X2 Dual-Core 5200+ @65W TDP
    Silverstone NT07 super slimline CPU cooler
    M2-ATX 160W PSU
    1GB DDR2 SODIMM
    Western Digital Scorpio Blue SATA 320GB
    Windows 7
    Voom2 enclosure

    My first external was only running 11.4V so no wonder it wouldn't power up. Second external power source is 12V and 5A. I've tried an normal PSU and the computer works fine. Is there a tutorial on how to modify a normal external PSU to run the PC on the bench?

  5. #5
    Maximum Bitrate fixerofallthing's Avatar
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    Quote Originally Posted by tag141 View Post
    Replied but don't know where the post went.

    Specs...

    J&W Minix Mini-itx AMD2 motherboard
    AMD Athlon™ 64 X2 Dual-Core 5200+ @65W TDP
    Silverstone NT07 super slimline CPU cooler
    M2-ATX 160W PSU
    1GB DDR2 SODIMM
    Western Digital Scorpio Blue SATA 320GB
    Windows 7
    Voom2 enclosure

    My first external was only running 11.4V so no wonder it wouldn't power up. Second external power source is 12V and 5A. I've tried an normal PSU and the computer works fine. Is there a tutorial on how to modify a normal external PSU to run the PC on the bench?
    yes there is here
    The Car 2005 Scion xB

    The Truck 2004 GMC Canyon

  6. #6
    High Voltage blk02si's Avatar
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    You're external power source is the culprit. 12v x 5a is only 60 Watts, which is the max your external power can provide. I can tell by your specs your hardware wants more juice than that. The m2 can supply a total of 160W, so in theory your external power should at minimum provide 160W or 160/12v which equals 13.3 amps. In reality you should be able to get away with a 12v 10 amp source since your not going to be maxing out the M2.

    Since the car creates 14.4 volts when running, the total amperage to run a fully loaded M2 would be 160w/14.4v which equals 11.1 amps. Again this is a fictitious scenario, but math does not lie.

    Simply put: Your setup will not work because it does not follow ohms law.
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  7. #7
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    Quote Originally Posted by fixerofallthing View Post
    yes there is here
    Quote Originally Posted by blk02si View Post
    Simply put: Your setup will not work because it does not follow ohms law.
    Beers all round. Fixer, top link. Will give that go in the morning. blk, great explanation. Extremely simple to understand.

  8. #8
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    IT'S ALIVE!!!

    Seriously, thanks for the help and information.

  9. #9
    High Voltage blk02si's Avatar
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    No Problem, glad we could help. Nice to see you got it going, let us know how the rest of the project turns out
    Build Things, it keeps your brain busy.

    AutoPC v1 (Retired) - AutoPC v2 (in progress) - www.shocknet.us

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