Power controller chip to turn on ATX
in [Home Built PC]
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From: Paul on 28 Oct 2009 14:09 Pennywise(a)DerryMaine.Gov wrote: > Al <bigal.nz(a)gmail.com> wrote: > >> Hi Guys, >> >> I have got a mobo here that is dead. I have done all the usual stuff >> like trying new PSU, bench testing etc. Its dead - as in no fans, no >> nothing when you hit PWR button - PSU doesnt even come on. >> >> I connected the ATX molex from the PSU and shorted Green (PWR ON) with >> GND on the molex and the PC came on. All seemed fine. >> >> I think there is a IC on the motherboard between the PWR BTN headers >>from the power on switch and the ATX header on the mobo that tells PSU >> to start up. > > Or the power supply, > http://www.pcguide.com/ref/power/sup/funcPowerGood-c.html > > Monitor the Gray wire (+5V & +3.3V is ok). > > -Also- > > You short purple (not Green, Green is the wrong wire). > You can get official wire colors, from the Intel specifications stored on the formfactors.org site. http://web.archive.org/web/20030424061333/http://www.formfactors.org/developer/specs/atx/ATX_ATX12V_PS_1_1.pdf (page 27) http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf (page 30) http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf (page 37) PS_ON#, the signal you ground to start an ATX power supply, is green. The purple colored wire is listed as "+5VSB" and you don't want to short that. It is a power output, not a control signal. ******* To drive PS_ON#, doesn't take a massive driver. The specs above, list a sinking current requirement of 1.6ma. In cases where there is a problem, it could be causes by the power supply being out of spec on that parameter. On the reference motherboard schematics I have here, some of the driving solutions could handle a lot more current than that, so whoever the designer was, they didn't take chances. Paul
From: chuckcar on 28 Oct 2009 18:00 Al <bigal.nz(a)gmail.com> wrote in news:6346b7b5-100b-4b30-b545-e8135f3436e5(a)m3g2000pri.googlegroups.com: > Hi Guys, > > I have got a mobo here that is dead. I have done all the usual stuff > like trying new PSU, bench testing etc. Its dead - as in no fans, no > nothing when you hit PWR button - PSU doesnt even come on. > > I connected the ATX molex from the PSU and shorted Green (PWR ON) with > GND on the molex and the PC came on. All seemed fine. > > I think there is a IC on the motherboard between the PWR BTN headers > from the power on switch and the ATX header on the mobo that tells PSU > to start up. > > I am trying to find this IC. > > I have attached a image of the mobo with some of the IC's that seem > possible labelled. > > http://www.badcaps.net/forum/attachment.php?attachmentid=12082 > > Interested to know if anyone knows which IC controls the PSU and tells > it to turn on? Someone else suggested this function was handled on the > CPU since P4, but I am not sure about that. > You *have* taken out all RAM and replace the CPU to test it right? If so, either replace capacitors or chuck it. -- (setq (chuck nil) car(chuck) )
From: Franc Zabkar on 28 Oct 2009 22:20 On Tue, 27 Oct 2009 01:03:07 -0700 (PDT), Al <bigal.nz(a)gmail.com> put finger to keyboard and composed: >Interested to know if anyone knows which IC controls the PSU and tells >it to turn on? Use a multimeter on the diode range to buzz the PCB. Connect one probe to the PS_ON pin in the ATX connector and connect a large sized square of aluminium foil to the other probe. Then press the foil against whole ICs, or whole sections of the PCB, until you get continuity. Not my idea - I think I first saw it at sci.electronics.repair. - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: Franc Zabkar on 28 Oct 2009 22:39
On Tue, 27 Oct 2009 11:33:18 -0700 (PDT), Al <bigal.nz(a)gmail.com> put finger to keyboard and composed: >Paul, > >Thanks for the very detailed replay.My bad for not remembering bad >caps wouldnt allow you to view the image. > >Here is the image: http://img101.imageshack.us/img101/4540/dsc04544a.jpg > >The motherboard is a Elite group L4S5MG/651 + V5.01 > >In addition to the other components: > >GS 78L05N (just aboce molex, 3 pin volt regulator) That's probably supplying a noise free +5V rail to the onboard sound chip ... for electret microphone biasing. >NEC K3296 MoSFET 2SK3296 >STLAB LD1117 (volatage regulator) I suspect this linear regulator may be reducing the +5VSB voltage to +3.3VSB. If you measure the voltages at the on/off header, I suspect you will find +3.3VSB rather than +5VSB. >But the one that seemed most likely was the RT9237 MULTIPHASE DC/ >DCCONTROLLER FOR CPU PWR SUPPLY > >This help any? > >And for those suggetsing bin it, yes I can do that, but there is no >learning in that! > >-Al Good on you! - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |