The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?

Catch 22?

John Hewitt, Malaga, Spain
*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

wrote:
The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?

Catch 22?

Because the power supply is never really completely off, but supplies
standby power to the motherboard.

wrote:
The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?

Catch 22?

John Hewitt, Malaga, Spain
*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from
http://www.SecureIX.com ***

Through a logic switching ic.

Or are you saying although the power switch is off at the back of the
supply you can still power up the pc via the front case ON button?
If so then it shouldn't be possible.

--
Sir Benjamin Middlethwaite

Grumps wrote:
wrote:
The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?

Catch 22?

Because the power supply is never really completely off, but supplies
standby power to the motherboard.

Not when the 240v switch on power supply itself is in the off position.

--
Sir Benjamin Middlethwaite

wrote:
The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?


Because the button is connected to the power supply via the
motherboard. The power supply is always in standby unless you hit turn
off the incoming mains.

MBQ

In article ,
wrote:
The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?

Catch 22?

You don't need (electrical) power to turn power on - just the means of making
a connection.

--
John Cartmell john@ followed by finnybank.com 0845 006 8822
Qercus magazine FAX +44 (0)8700-519-527 www.finnybank.com
Qercus - the best guide to RISC OS computing

On Wed, 22 Mar 2006 11:04:21 +0100, wrote:

The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?

Catch 22?

There is a permanent 5v line going to the motherboard which is used to
power a circuit that monitors the push button. When the button is
pressed it sends a signal to the psu that tells it to power up
completely.

sponix

The message
from contains these words:

Thanks for the info. Would that 5volt line feeding the MBoard, be
fused? Maybe that's why I can't turn the PC ON.

Is the PSU switched on? Some have a little switch on the back panel.

--
Skipweasel
Pay no attention to the man behind the curtain.

wrote:

Thanks for the info. Would that 5volt line feeding the MBoard, be
fused? Maybe that's why I can't turn the PC ON.

Not usually fused IME. If you are sure the PSU is on (some have a
physical mains input switch on the back), check the power switch is
working correctly (should be a push to make switch). If that is OK (or
even if not) you ought to be able to get the board to power up by
shorting the power on pins on the MB. Note some boards require a working
processor to be fitted before they will power up.

If that does not work then you either have a dead PSU or motherboard.
You can test the PSU by disconnecting the MB connector (leave a CD ROM
drive or something connected because this type of PSU will not run
without any load) and use a small wire to short the green wire on the
ATX connector to one of the adjacent black ones. That should cause the
PSU to come on. If it does not then replace the PSU, if it does then
replace the motherboard.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John. Thank you for the info, and the direction. Followed thru with
your guide and found, that the PSU fired up on shorting green to Blk
wires.
Hmm. Re-connected PSU to the mboard and damned, but it started again.
So I have an intermittent somewhere most likely the power connector to
the mboard - I'd surmise?
Thanks again.

On Wed, 22 Mar 2006 15:01:15 +0000, John Rumm
wrote:

wrote:

Thanks for the info. Would that 5volt line feeding the MBoard, be
fused? Maybe that's why I can't turn the PC ON.

Not usually fused IME. If you are sure the PSU is on (some have a
physical mains input switch on the back), check the power switch is
working correctly (should be a push to make switch). If that is OK (or
even if not) you ought to be able to get the board to power up by
shorting the power on pins on the MB. Note some boards require a working
processor to be fitted before they will power up.

If that does not work then you either have a dead PSU or motherboard.
You can test the PSU by disconnecting the MB connector (leave a CD ROM
drive or something connected because this type of PSU will not run
without any load) and use a small wire to short the green wire on the
ATX connector to one of the adjacent black ones. That should cause the
PSU to come on. If it does not then replace the PSU, if it does then
replace the motherboard.

John Hewitt, Malaga, Spain
*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

In message , The3rd
Earl Of Derby writes
Grumps wrote:
wrote:
The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?

Catch 22?

Because the power supply is never really completely off, but supplies
standby power to the motherboard.

Not when the 240v switch on power supply itself is in the off position.

Well, DUH !

--
geoff

wrote:
John. Thank you for the info, and the direction. Followed thru with
your guide and found, that the PSU fired up on shorting green to Blk
wires.
Hmm. Re-connected PSU to the mboard and damned, but it started again.
So I have an intermittent somewhere most likely the power connector to
the mboard - I'd surmise?
Thanks again.

On Wed, 22 Mar 2006 15:01:15 +0000, John Rumm
wrote:

wrote:

Thanks for the info. Would that 5volt line feeding the MBoard, be
fused? Maybe that's why I can't turn the PC ON.

Not usually fused IME. If you are sure the PSU is on (some have a
physical mains input switch on the back), check the power switch is
working correctly (should be a push to make switch). If that is OK
(or even if not) you ought to be able to get the board to power up by
shorting the power on pins on the MB. Note some boards require a
working processor to be fitted before they will power up.

If that does not work then you either have a dead PSU or motherboard.
You can test the PSU by disconnecting the MB connector (leave a CD
ROM drive or something connected because this type of PSU will not
run without any load) and use a small wire to short the green wire
on the ATX connector to one of the adjacent black ones. That should
cause the PSU to come on. If it does not then replace the PSU, if it
does then replace the motherboard.

John Hewitt, Malaga, Spain
*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from
http://www.SecureIX.com ***

Faulty PTS(push to make switch)

--
Sir Benjamin Middlethwaite

On Wed, 22 Mar 2006 18:58:56 +0100, wrote:

John. Thank you for the info, and the direction. Followed thru with
your guide and found, that the PSU fired up on shorting green to Blk
wires.
Hmm. Re-connected PSU to the mboard and damned, but it started again.
So I have an intermittent somewhere most likely the power connector to
the mboard - I'd surmise?
Thanks again.
SNIP

Not seen previous posts, but my pSU fired up similarly but pc not,
replaced cmos battery -------- all fine now!

PC power supplies are notoriously unreliable - they are usually the
first thing that goes. However at £20 to £30 even from Maplin that's
a tolerable replacement.

Rob