Useing AT switcher as bench supply.

S

Scott Wiper

Guest
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use the 12
volts with the switcher going into shut down. I have modded one with molex
connectors on the back for inserting power clips and banana plugs for my
solderless board.

If I take the power good to ground will this work like a ATX switcher where
the green is is taken to ground for PS_ON?

--
My cat Tigger says every morning...
"Before my morning coffee... I might as well be a dog!"
To contact follow the link below. JavaScript Must be enabled
http://www.travel-net.com/~selen3701/email.htm
 
You do realize that switching psu tend to explode if they are left
without loads on the outputs, right?

- Tim -



In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use the 12
volts with the switcher going into shut down. I have modded one with molex
connectors on the back for inserting power clips and banana plugs for my
solderless board.

If I take the power good to ground will this work like a ATX switcher where
the green is is taken to ground for PS_ON?
Click to expand...
 
Behold, Tim signalled from keyed 4-1000A filament:

You do realize that switching psu tend to explode if they are left
without loads on the outputs, right?

- Tim -
Click to expand...
Eh?

I've been using an XT switcher for a 12V/5V bench supply for years :-/

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca
 
On most supplies you need the resistor, it's there for loading, not for
turning on the supply. A switcher of that type needs a load to function
properly, leaving it out will likely result in the switcher not turning
on, or turning itself off. Some will even be damaged. TTYL

On Tue, 13 Jul 2004 19:22:42 +0000, Tim wrote:

You do realize that switching psu tend to explode if they are left without
loads on the outputs, right?

- Tim -



In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use
the 12 volts with the switcher going into shut down. I have modded one
with molex connectors on the back for inserting power clips and banana
plugs for my solderless board.

If I take the power good to ground will this work like a ATX switcher
where the green is is taken to ground for PS_ON?
Click to expand...
 
While theoretically true, almost all PC power supplies will not "explode",
and to say so is fear mongering, at best.

Most PC power supplies will simply shut down (or not start up). Some
better supplies have internal loading so that no external load is required.

I usually plug in an old hard drive as a load, has worked every time. TTYL

On Tue, 13 Jul 2004 19:22:42 +0000, Tim wrote:

You do realize that switching psu tend to explode if they are left without
loads on the outputs, right?

- Tim -



In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use
the 12 volts with the switcher going into shut down. I have modded one
with molex connectors on the back for inserting power clips and banana
plugs for my solderless board.

If I take the power good to ground will this work like a ATX switcher
where the green is is taken to ground for PS_ON?
Click to expand...
 
"Tim" <tim@tim.tim> wrote in message
news:MPG.1b5e0e95e4863e6798969c@allnews.nbnet.nb.ca...
You do realize that switching psu tend to explode if they are left
without loads on the outputs, right?

- Tim -

Damn, you told him! We wanted to see if we could get an Ottawan winning the
Click to expand...
Darwin Awards ;)

In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use
the 12
volts with the switcher going into shut down. I have modded one with
molex
connectors on the back for inserting power clips and banana plugs for my
solderless board.

If I take the power good to ground will this work like a ATX switcher
where
the green is is taken to ground for PS_ON?
Click to expand...
 
"Mjolinor" <mjolinor@hotmail.com> wrote in message
news:5BYIc.292$Av5.149@newsfe6-win.ntli.net...
"Scott Wiper" <nobody@devnull.spamcop.met> wrote in message
news:ZdWIc.25329$vO1.139286@nnrp1.uunet.ca...
Click to expand...

AFAIK Power good on an AT supply is an output to tell the Mboard that the
power supply is stable, not an input. If you have no output it is because
there is no load probably.

You need to google.
Click to expand...

I will google this one out. AT switchers need a load connected to them ATX
switchers will switch on when there when a load is detected. I think is to
prevent output caps from bursting.

I will use a old poor quailty ATX switcher with a SPST switch a 1K resistor
and a green LED to ground for power on. I also Modded that one with molex
connectors. I put the extra wires out for that.
 
"Scott Wiper" <nobody@devnull.spamcop.met> wrote in message
news:ZdWIc.25329$vO1.139286@nnrp1.uunet.ca...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use the
12
volts with the switcher going into shut down. I have modded one with molex
connectors on the back for inserting power clips and banana plugs for my
solderless board.

If I take the power good to ground will this work like a ATX switcher
where
the green is is taken to ground for PS_ON?
Click to expand...
AFAIK Power good on an AT supply is an output to tell the Mboard that the
power supply is stable, not an input. If you have no output it is because
there is no load probably.

You need to google.
 
Tim wrote:

You do realize that switching psu tend to explode if they are left
without loads on the outputs, right?

- Tim -
Click to expand...
I've seen electrolytic caps explode when subjected to overvoltage.

But power supplies for PCs, for as long as I can remember, have had
overvoltage shutdown that prevents them from doing anything except shut
down.


In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...

Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use the 12
volts with the switcher going into shut down. I have modded one with molex
connectors on the back for inserting power clips and banana plugs for my
solderless board.

If I take the power good to ground will this work like a ATX switcher where
the green is is taken to ground for PS_ON?
Click to expand...
 
I have the scars to prove it. Some switching psu will take off with no
load, and the freq will exceed spec and bang! they go ballistic.

Been there, done that.



In article <pan.2004.07.13.20.39.09.524715@yahoo.com>, repatch42
@yahoo.com says...
While theoretically true, almost all PC power supplies will not "explode",
and to say so is fear mongering, at best.

Most PC power supplies will simply shut down (or not start up). Some
better supplies have internal loading so that no external load is required.

I usually plug in an old hard drive as a load, has worked every time. TTYL

On Tue, 13 Jul 2004 19:22:42 +0000, Tim wrote:

You do realize that switching psu tend to explode if they are left without
loads on the outputs, right?

- Tim -



In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use
the 12 volts with the switcher going into shut down. I have modded one
with molex connectors on the back for inserting power clips and banana
plugs for my solderless board.

If I take the power good to ground will this work like a ATX switcher
where the green is is taken to ground for PS_ON?
Click to expand...
 
Then it was a VERY poor design and it's scary it was ever in a PC. I can't
believe it would have passed the safety standards in most countries. TTYL

On Wed, 14 Jul 2004 00:44:14 +0000, Tim wrote:

I have the scars to prove it. Some switching psu will take off with no
load, and the freq will exceed spec and bang! they go ballistic.

Been there, done that.



In article <pan.2004.07.13.20.39.09.524715@yahoo.com>, repatch42
@yahoo.com says...
While theoretically true, almost all PC power supplies will not
"explode", and to say so is fear mongering, at best.

Most PC power supplies will simply shut down (or not start up). Some
better supplies have internal loading so that no external load is
required.

I usually plug in an old hard drive as a load, has worked every time.
TTYL

On Tue, 13 Jul 2004 19:22:42 +0000, Tim wrote:

You do realize that switching psu tend to explode if they are left
without loads on the outputs, right?

- Tim -



In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with
out useing a 1R 50watt resistor on the five volt line so I could just
use the 12 volts with the switcher going into shut down. I have
modded one with molex connectors on the back for inserting power
clips and banana plugs for my solderless board.

If I take the power good to ground will this work like a ATX switcher
where the green is is taken to ground for PS_ON?
Click to expand...
 
On Wed, 14 Jul 2004 00:44:14 GMT, Tim <tim@tim.tim> wrote:

I have the scars to prove it. Some switching psu will take off with no
load, and the freq will exceed spec and bang! they go ballistic.

Been there, done that.
Click to expand...
A common switcher CAN do this, but a CSA approved, or UL approved in
the US of A computer power supply MUST protect itself from this. They
all have overvoltage and over current shut-down..
One thing that makes them kinda nice for bench supplies.
In article <pan.2004.07.13.20.39.09.524715@yahoo.com>, repatch42
@yahoo.com says...
While theoretically true, almost all PC power supplies will not "explode",
and to say so is fear mongering, at best.

Most PC power supplies will simply shut down (or not start up). Some
better supplies have internal loading so that no external load is required.

I usually plug in an old hard drive as a load, has worked every time. TTYL

On Tue, 13 Jul 2004 19:22:42 +0000, Tim wrote:

You do realize that switching psu tend to explode if they are left without
loads on the outputs, right?

- Tim -



In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with out
useing a 1R 50watt resistor on the five volt line so I could just use
the 12 volts with the switcher going into shut down. I have modded one
with molex connectors on the back for inserting power clips and banana
plugs for my solderless board.

If I take the power good to ground will this work like a ATX switcher
where the green is is taken to ground for PS_ON?
Click to expand...
 
Nothing stopping you from trying it.
<nospam.clare.nce@snyder.on.ca> wrote in message
news:g949f0ts31sem4dnkenut4hnofkn2qlnj0@4ax.com...
On Wed, 14 Jul 2004 00:44:14 GMT, Tim <tim@tim.tim> wrote:

I have the scars to prove it. Some switching psu will take off with no
load, and the freq will exceed spec and bang! they go ballistic.

Been there, done that.

A common switcher CAN do this, but a CSA approved, or UL approved in
the US of A computer power supply MUST protect itself from this. They
all have overvoltage and over current shut-down..
One thing that makes them kinda nice for bench supplies.



In article <pan.2004.07.13.20.39.09.524715@yahoo.com>, repatch42
@yahoo.com says...
While theoretically true, almost all PC power supplies will not
"explode",
and to say so is fear mongering, at best.

Most PC power supplies will simply shut down (or not start up). Some
better supplies have internal loading so that no external load is
required.

I usually plug in an old hard drive as a load, has worked every time.
TTYL

On Tue, 13 Jul 2004 19:22:42 +0000, Tim wrote:

You do realize that switching psu tend to explode if they are left
without
loads on the outputs, right?

- Tim -



In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...
Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on with
out
useing a 1R 50watt resistor on the five volt line so I could just
use
the 12 volts with the switcher going into shut down. I have modded
one
with molex connectors on the back for inserting power clips and
banana
plugs for my solderless board.

If I take the power good to ground will this work like a ATX
switcher
where the green is is taken to ground for PS_ON?
Click to expand...
 
Tim wrote:

I have the scars to prove it. Some switching psu will take off with
no load, and the freq will exceed spec and bang! they go ballistic.

Been there, done that.
Click to expand...
I've seen 12V equipment lift off the bench when connected to a 28VDC
power supply; so yeah, those electrolytic caps can be quite destructive
when they let go. I've also seen the insides of equipment afterwards,
where the shreds of the 'lytic are stuck all over the rest of the
components on the PC board. So I can relate to the shrapnel that you've
experienced. But all the PSes that I've seen have a crowbar OVP circuit
that just shorts the output to ground with a SCR when the overvoltage is
encountered.

In article <pan.2004.07.13.20.39.09.524715@yahoo.com>, repatch42
@yahoo.com says...

While theoretically true, almost all PC power supplies will not
"explode", and to say so is fear mongering, at best.

Most PC power supplies will simply shut down (or not start up).
Some better supplies have internal loading so that no external load
is required.

I usually plug in an old hard drive as a load, has worked every
time. TTYL

On Tue, 13 Jul 2004 19:22:42 +0000, Tim wrote:

You do realize that switching psu tend to explode if they are
left without loads on the outputs, right?

- Tim -

In article <ZdWIc.25329$vO1.139286@nnrp1.uunet.ca>,
nobody@devnull.spamcop.met says...

Their is a white wire that is labelled power good.

I would like to trick this supply into thinking it is fully on
with out useing a 1R 50watt resistor on the five volt line so I
could just use the 12 volts with the switcher going into shut
down. I have modded one with molex connectors on the back for
inserting power clips and banana plugs for my solderless board.
If I take the power good to ground will this work like a ATX
switcher where the green is is taken to ground for PS_ON?
Click to expand...
 
"repatch" <repatch42@yahoo.com> wrote in message
news:pan.2004.07.13.20.35.50.751622@yahoo.com
On most supplies you need the resistor, it's there for loading, not
for turning on the supply. A switcher of that type needs a load to
function properly, leaving it out will likely result in the switcher
not turning
on, or turning itself off. Some will even be damaged. TTYL
Click to expand...
Or (just to add another to the list of possibilities) it just won't
regulate accurately. That could also affect regulation of the 12V
output.
 
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