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Motherboard only start with Green/Black cable trick

Hi everyone,

I made a video to explain my issue , here :
----> Motherboard won't start with power button - only with Green and Black cable ATX trick <----

// Sorry in advance for my badly formulated english, will try to be short.

Ok here my problem :
- I recieve a PC (P4 on 478 socket) to reformat it becose it was really slow
- Just before formating it suddently shutdown
- After testing RAM, CPU ... etc I found that thhe MoBo itself was dead
- So I bought a new MoBo
- The I plug the ATX connector and push de power bouton (PWR_SW in F_Panel) I see the fans begin to spin and stop for 3 seconds and smell a light electronic burn with heat near the pins of PWR_SW (around F_Panel pins in fact)
- So I just realize that the original Power Suply (PSU) given bad voltage or somiting like that
- thus I change de PSU with a new one
- shorting pins of PWR_BTN make nothing ***
- only way to power up this MoBo is to short Green and Black cable fromt ATX connector
- The computer was formated and work really fine ...

... but if I leave Green/Black short I can't Shutdown, it restart after Windows is close

I can also start the MoBo by shorting Green/black for 3-4 seconds and release the short ... but is not user-frendly for someone that expect his computer start with power buuton in front panel

Someone know how can I deal with this problem ?

Shorting in other place the power button somewher ?

*** in fact randomly if I push successively the FontPanel Power Button sometimes it works to start but its very random...

Maybe a resitor, capacitor or mofset defect but which one ?

Also : When I push to Power Off it's working fine (from DOS/Windows) ACPI S3/S1 working to shutdown but not to power up.

Thanks in advance for genius who can help me.

Cheers
13 answers Last reply
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  1. pffff ... each time I post something on a forum I've never a reply ... Why ?
    Is it my english to bad to understand ?
    Or it thius just becose I searched first on Google and tried all what is possible ?

    Hope that my Green/Black Trick helps someone a day ...

    I tried to put a LED on the PWR_SW pins and then short the pin, it seem to work in less than 5 attempts.

    I'm sure that I can put a resistor or capacitor to 'emulate' PS_ON signal, but I'm not electrician so I dunno which value of component should I use.

    Thanks to read me.

    Cheers.
  2. The power switch is what's called a "soft" power switch. It doesn't really close a circuit - like you're doing with shorting the green/black, but does so only for a moment. This isn't a completely correct explanation, but is close. When Windows shuts down the computer, it sees the connection shorted and thinks it has lost power and follows the instructions in the BIOS for handling this situation - either stay off or restart - and it restarts.

    I think the problem with your PSU damaged the Power switch you have - or the switch was bad and that was the problem to begin with. I would try replacing the power switch - sounds like you may have a few extra parts laying around.

    The switch on the PSU is a real on/off switch, unlike the panel switch. You may be able to just control the computer using it, but not on all motherboards. I had one that would turn on automatically if shut down with PSU switch and another that would not.

    Hopes this helps somewhat. Problems with getting an answer may be the location of your question, you put it in Chipsets & BIOS. Your English is good - not perfect! - but likely far better than if I tried to write in your language!!!
  3. Thanks for replying :)

    The power switch is what's called a "soft" power switch. It doesn't really close a circuit - like you're doing with shorting the green/black, but does so only for a moment. This isn't a completely correct explanation, but is close. When Windows shuts down the computer, it sees the connection shorted and thinks it has lost power and follows the instructions in the BIOS for handling this situation - either stay off or restart - and it restarts.

    I think the problem with your PSU damaged the Power switch you have - or the switch was bad and that was the problem to begin with. I would try replacing the power switch - sounds like you may have a few extra parts laying around.

    But when trying I'm just shorting the PIN with metal piece (coin, screwdriver ...) but it the same with wired Front Panle Power Button
    The Mobo is on a wooden table and I allways shorts pin's to start-up a MoBo
    Do you think placing another Push Button will solve the issue ?

    I will try it on monday.

    Quote:

    The switch on the PSU is a real on/off switch, unlike the panel switch. You may be able to just control the computer using it, but not on all motherboards. I had one that would turn on automatically if shut down with PSU switch and another that would not.

    Hopes this helps somewhat. Problems with getting an answer may be the location of your question, you put it in Chipsets & BIOS. Your English is good - not perfect! - but likely far better than if I tried to write in your language!!!


    The computer is not for me but for a newbie who wants his computer fits on a furniture, and have no easy acces to the rear I/O switch.

    Thank you a lot.

    Cheers.
  4. oops, I putted my reply in your quotemsg :

    But when trying I'm just shorting the PIN with metal piece (coin, screwdriver ...) but it the same with wired Front Panle Power Button
    The Mobo is on a wooden table and I allways shorts pin's to start-up a MoBo
    Do you think placing another Push Button will solve the issue ?

    I will try it on monday.

    Quote:

    The switch on the PSU is a real on/off switch, unlike the panel switch. You may be able to just control the computer using it, but not on all motherboards. I had one that would turn on automatically if shut down with PSU switch and another that would not.

    Hopes this helps somewhat. Problems with getting an answer may be the location of your question, you put it in Chipsets & BIOS. Your English is good - not perfect! - but likely far better than if I tried to write in your language!!!


    The computer is not for me but for a newbie who wants his computer fits on a furniture, and have no easy acces to the rear I/O switch.

    Thank you a lot.

    Cheers.
  5. OK, I think I understand what you're doing now. I thought you were shorting the on/off switch's wires. You're actually shorting the wires from the PSU to the motherboard? The green and black wires there? Heck, no idea what that will do or what it will cause in terms of problems long-term.

    I'm going to ask someone here that knows power supplies and wiring well to look at this thread.
  6. Mongox said:
    OK, I think I understand what you're doing now. I thought you were shorting the on/off switch's wires. You're actually shorting the wires from the PSU to the motherboard? The green and black wires there? Heck, no idea what that will do or what it will cause in terms of problems long-term.

    I'm going to ask someone here that knows power supplies and wiring well to look at this thread.


    Great that you spend time on my case, I really appreciate.

    Yup, The First PSU (200W) burned the first MoBo (but I didn't know at this time that the problem was PSU
    I changed the MoBo with a brand new one but with the same PSU (200W) but the new MoBo need at least 300W (dunno if affect, normally it should be the PSU burn)
    The First PSU burned also the new MoBo but not entirely

    So now indeed, with a brand new PSU and my brand new burned MoBo I can use it by shorting cable Green and Black from the ATX connector. for about less 2 seconds (if I do it to fast fan's begin to spin and stops) It's working also if I stay shorting.

    But sometimes I can startup the MoBo shorting pin's PWR_BTN on the mainboard (where you put ussualy the wire for the front power button) but it's very random (5 to 10 times to push button or shorting pin's)

    I read I bit about the normal power-on (Soft-on) ignition sequence what I uderstand :
    Logic level is LOW -Output voltage is enabled (PS_ON pin)
    Logic level is HIGH -Output voltage is disabled (PS_ON pin)

    In fact the "signal" to Power On is only a variation of voltage in a specific time perdiod (in milisecond; ms)
    On stand by/computer off (pin open) it should be 3-5V , on power Soft-on (pin shorted/power button pressed) it should fall to 0.15V (or below 0.8V) in less than 22 ms if I'm not wrong.

    Probably an elecronical component (resistor, capacitor or FET) had hot and his value has changed

    I'm just wondering I it is possible either :
    - to repair this components (I m sure not in fact, it to small now, impossible to solder on the PCB MoBo)
    - reproduce to Power On "signal" (voltage variation in period) with an electronic component wierd on pin's or somewhere else on the MoBo.
    - solder Power Button wires somewhere else on the mobo (near a chip? on PCI pin ?
    - use a PCI device (if exist) where I can wire the power button
    - exploit Wake up RTC, PCI, to reproduce a Soft-on.
    - or other alternative for the End-User whom just have to push the front Power Button (who don't care what is in the box if it works "normally")

    The computer is for an old man so I don't will use the Power Switch on rear PSU

    I'll already tried to exploit ACPI technology in BIOS to enable key pressed on PS/2 or USB Keyboard/mouse but don't work too :fou:

    I have also bought an PCI Diagnostic POST card analyzer (1 €/$ on eBay) look like this :

    According to the LED's on it I have no trouble about current/voltage (+3, +5 , +12 etc...)
    And Post Code, accordin to the booklet, seem to be normal POST code.

    Normal Power Off (Soft-Off) works fine thru Windows (Start > Shutdown) and also by pressing button (or short pin) the "signal" in this way works to power off properly.

    It's only Soft-on that doesn't work.

    And again thanx
  7. Ok I found the document that explain the " PS_ON# Signal Characteristics "

    Page 26/27

    For reference

    Cheers
  8. Your knowledge is above mine in this area! I have asked someone with more experience to look over this thread and comment.

    Good luck and I hope you get it working well enough for the older man.
  9. To be sure I understand - you are doing this (screwdriver - lower picture) and the computer is not starting?
  10. bilbat said:
    To be sure I understand - you are doing this (screwdriver - lower picture) and the computer is not starting?
    http://img401.imageshack.us/img401/8053/0094h.jpg


    Yes I'm doing this and the computer doesn't start.

    ... but sometime's yes if I push power button (or using screwdriver to short pin's) 5-10 times successively randomly it starts.

    I can start also by shorting Green (PS_ON) and a Black (COM) cable from the ATX connector

    Cheers
  11. If a solid, consistent shorting of those two pins on the front panel connector does not cosistently start the board, I would RMA it, it is defective...

    http://www.gigabyte.com.tw/Support/ServiceCenter.aspx
  12. bilbat said:
    If a solid, consistent shorting of those two pins on the front panel connector does not cosistently start the board, I would RMA it, it is defective...

    http://www.gigabyte.com.tw/Support/ServiceCenter.aspx


    It's an ECS motherboard, and the PSU burned the MotherBoard (so it's my fault), this motherboard is discontinued from ECS.
    I bought this MoBo in second hand in a ghetto, the vendor show me it working, so I can't go back to him and say "Your MoBo doesn't work" becose it woked fine before I puted the first bad PSU

    Thanks for advice.
  13. Hi,

    To avoid misunderstanding I made a video to explain my problem :

    http://www.youtube.com/watch?v=nYb7UaWip8w


    Cheers
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