Power controller chip to turn on ATX

[Al]

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.

Thanks


-Al

RT9237 : http://www.alldatasheet.com/view.jsp?Searchword=RT9237
93705CF : http://www.ic2ic.com/search.jsp?sSe...3705CF&prefix=9
952001AF : http://www.alldatasheet.com/view.js...chword=952001AF
2N03L : http://www.alldatasheet.com/view.jsp?Searchword=2N03L08
LD117 : http://www.st.com/stonline/products...fo/ld1117_1.htm
RT9602 : http://www.alldatasheet.com/view.jsp?Searchword=RT9602

 

[david]

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.

Thanks


-Al

I would check first that you have the power button wired correctly.

 

[Grinder]

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.

If you short the power button pins on the motherboard's front panel
header, will it start up?

I'm sorry I can't be more specific about where those pins are as I don't
know what motherboard you have. (I don't have a badcaps.net login.) If
you identify the motherboard, I can give you a more specific answer.

 

[Desk Rabbit]

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.

Assumming you can identify the chip, and assuming you can safely
unsolder it without breaking the board and assuming you can solder the
new one in without breaking it or the board, I'd suggest a new mother board.

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

Give us a login and we will be able to view that.

 

[Paul]

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.

Thanks


-Al

RT9237 : http://www.alldatasheet.com/view.jsp?Searchword=RT9237
93705CF : http://www.ic2ic.com/search.jsp?sSe...3705CF&prefix=9
952001AF : http://www.alldatasheet.com/view.js...chword=952001AF
2N03L : http://www.alldatasheet.com/view.jsp?Searchword=2N03L08
LD117 : http://www.st.com/stonline/products...fo/ld1117_1.htm
RT9602 : http://www.alldatasheet.com/view.jsp?Searchword=RT9602

Any chance of posting the badcaps image, on one of the free image hosting
sites ?

In terms of your notion of figuring it all out, based on a picture,
that isn't likely to happen.

I have three reference schematics here, and they all implement that
function in a different manner.

First off all, there is a whole chain of logic associated with that
function. It includes the Southbridge (Wake on USB keyboard, Wake on
scheduled RTC time, Wake on PME from PCI bus), the SuperI/O
(Wake on Ring on serial port, Wake on PS/2 keyboard keypress), plus
some external jelly bean logic. Those chips contribute reasons why
the power should be switched on.

One schematic, uses a 2N3904 transistor as the interface to pin 14
on the 20 pin ATX power connector. The interface is open collector
logic, so a transistor can be used as the driver.

Another one, uses a Fairchild 14 pin TTL logic chip, with open
collector output drive, to control the signal on pin 14.

The third schematic uses a custom chip, with no data available,
to drive the signal directly.

So even if you do post a picture of the motherboard, and the
resolution of the picture is high enough to read all the chips,
it still may not be possible to guess at the method. Chips don't
have to be placed in proximity to the driven thing. So you
won't necessarily see the "guilty party" sitting right next
to the 20 pin connector. There is no requirement in a layout,
that a driving chip be placed right next to the load. It
could be all the way across the motherboard, on the other
side of the board.

Paul

 

[Al]

Any chance of posting the badcaps image, on one of the free image hosting
sites ?

In terms of your notion of figuring it all out, based on a picture,
that isn't likely to happen.

I have three reference schematics here, and they all implement that
function in a different manner.

First off all, there is a whole chain of logic associated with that
function. It includes the Southbridge (Wake on USB keyboard, Wake on
scheduled RTC time, Wake on PME from PCI bus), the SuperI/O
(Wake on Ring on serial port, Wake on PS/2 keyboard keypress), plus
some external jelly bean logic. Those chips contribute reasons why
the power should be switched on.

One schematic, uses a 2N3904 transistor as the interface to pin 14
on the 20 pin ATX power connector. The interface is open collector
logic, so a transistor can be used as the driver.

Another one, uses a Fairchild 14 pin TTL logic chip, with open
collector output drive, to control the signal on pin 14.

The third schematic uses a custom chip, with no data available,
to drive the signal directly.

So even if you do post a picture of the motherboard, and the
resolution of the picture is high enough to read all the chips,
it still may not be possible to guess at the method. Chips don't
have to be placed in proximity to the driven thing. So you
won't necessarily see the "guilty party" sitting right next
to the 20 pin connector. There is no requirement in a layout,
that a driving chip be placed right next to the load. It
could be all the way across the motherboard, on the other
side of the board.

    Paul

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)
NEC K3296 MoSFET
STLAB LD1117 (volatage regulator)

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

 

[Al]

Dried out electrolytic capacitors in the RAM/CPU voltage regulation
circuit. Toss the ****ing mobo in the trash or send it to be
re-capped.

Yeah, thats been suggested. There are no signs of bulding or venting.

I took one of them off (they are OST brand) and checked it with my ESR
meter. It had ESR of 0.02 so prob stll good and was pretty close to
itrs rated 470uf (it was at about 5300uf).

I know that to be sure I really need to test them all, Not sure if
this would cause my symptom tho?

-Al

 

[Al]

If you short the power button pins on the motherboard's front panel
header, will it start up?

I'm sorry I can't be more specific about where those pins are as I don't
know what motherboard you have.  (I don't have a badcaps.net login.)  If
you identify the motherboard, I can give you a more specific answer.

Yep good suggestion and yes I have done that.

 

[Grinder]

Yep good suggestion and yes I have done that.

Did the PC startup? I guess it must not have if you still consider the
motherboard to have a problem.

If there is a chip that is bad, as you've suggested, it's unlikely that
you'll be able to affect a repair. Since you've tried another power
supply already, it's getting near to the point where you have to cut
your losses.

 

[Pennywise]

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).

"Why the computer/fan does not turn on after flipping the power
supply's switch to the ON position?
ATX power supplies differ from AT power supplies in several important
regards. Major among these is that ATX supplies depend on logic
circuits on the motherboard to turn it on. Once the power switch is
flipped, the power switch on the ATX power supply (some ATX power
supplies do not even have such a switch), the ATX power supply sends a
5V 720MA current to the motherboard through pin 9 on the power
connector. That current is for WOL (Wake-up On Lan) and power on
circuits. A power-on jumper on the motherboard connects to the
pushbutton located in front of ATX case. When the pushbutton is
pressed, it sends a signal to the motherboard, which in turn notifies
the ATX power supply to turn on full power. The location of the
power-on jumper on the motherboard is manufacture dependent. One needs
to read the motherboard manual to locate that jumper. At any event, do
not try to manually jump-start the power supply without attaching the
motherboard. The power supply is expecting certain sensing circuit
feedback to regulate the output voltage, manually starting it without
attaching it to the motherboard could cause damage to the power
supply."

http://www.bluemax.net/techtips/ATXPowerSupplyWiring/ATXPowerSupplyWiring.htm
I have always linked this page, it appears to be no more.

It was a very good site on ATX power supplies, I have the web pages of
interest if you want them.

I have a digital DC voltage display with two clips on long wires, just
made for something like this. I was given two of them, each had
instructions to wire them for different functions - I went with DC
voltage.
- very nice to have handy to monitor voltages.-
--

You've got three months to grab what you need.
http://torrentfreak.com/the-pirate-bay-ordered-to-delete-torrents-091022/
And
http://gizmodo.com/5387909/hulus-glorious-free-days-are-officially-numbered

 

[Paul]

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/20030424...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

 

[chuckcar]

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.

 

[Franc Zabkar]

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

 

[Franc Zabkar]

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