Micro P4ATX 200W (3 Screw SFX)
Switching Power Supply

AC INPUT: 115/230 Vac~ 8/4A
60/50Hz
DC OUTPUT :

COLOR : BROWN RED WHITE YELLOW BLUE PURPLE BLACK
GREEN ORANGE
DC : +3.3V +5V -5V +12V -12V
+5V-SB COM PS-ON PW-OK
OUTPUT : 11.5/18.7A 16/13A 0.3A 11A 0.3A
2.0A RETURN REMOTE P.G.

(3.3V and 5V Max Output 120W, Peak Surge Max Output 208W)

Hello all,
I'm having some trouble turning the above label power supply on. I.E. I'd
like it to run outside of the computer.
I'll be using this power supply to run a CNC engraver. The motors are
three(3) 6vdc unipolar.
I read elsewhere that I have to supply a small load across one of the red
and com leads.
Such as an old cdrom or 25ohm resistor. I really don't want to use the cdrom
drive as it will increase the weight of
my unit and I'm sure one of you guys are quite capable of creating a load
that would be necessary to make this work.

The site below and accompanying text is the controller unit that drives the
motors
http://www.stepper3.com/index.htm?31.htm&1
(S3ROC) Stepper3 Rev OC - 3 Axis 3 Amp Unipolar Stepper Motor Driver



I do have an older style AT box that will come on with the switch, but it
seems to power down as soon as my three motors are running in unison. The
fella at the site indicated below used 10ohm/10watt power resistors. How
exactly he set them up is beyond me. He called them power limiters. I was
assuming that the current draw from three motors running simultaneously
(6vdc unipolar) would cause the power supply to shut down???????

http://www.theworkshop.ca/metcastmac...FoamMill13.htm

Any help or a crude schematic would be extremely helpful.

Peace
Neil

Some switching power supplies require a load. Some do not.
Minimum load is a design function that is also defined in
specifications provided by that power supply manufacturer.

Without a 3.5 digit multimeter, then you must have plenty of
time to waste. Otherwise get that multimeter. Begin by
measuring voltages on purple and green wires - relative to
ground - black wire.

Most switching power supplies will at least do something
even without a load. Get the meter.

Neil Jackson wrote:
I've tried that, and nothing seems to be happening. I'm tinkering
a little more. I also read something about a tester with a
60w/6ohm resistor connected between ??purple/orange???
Thank you for the response.
Neil

Find the Saint Louis switcher article on the web.

Has all the details on using an ATX PS stand alone.

5 ohm 10 watt resister between the red and black output wires to load the 5
volt section

Hugh
"w_tom" wrote in message
...
Some switching power supplies require a load. Some do not.
Minimum load is a design function that is also defined in
specifications provided by that power supply manufacturer.

Without a 3.5 digit multimeter, then you must have plenty of
time to waste. Otherwise get that multimeter. Begin by
measuring voltages on purple and green wires - relative to
ground - black wire.

Most switching power supplies will at least do something
even without a load. Get the meter.

Neil Jackson wrote:
I've tried that, and nothing seems to be happening. I'm tinkering
a little more. I also read something about a tester with a
60w/6ohm resistor connected between ??purple/orange???
Thank you for the response.
Neil

"w_tom" wrote in message
...
Some switching power supplies require a load. Some do not.
Minimum load is a design function that is also defined in
specifications provided by that power supply manufacturer.

Without a 3.5 digit multimeter, then you must have plenty of
time to waste. Otherwise get that multimeter. Begin by
measuring voltages on purple and green wires - relative to
ground - black wire.

Most switching power supplies will at least do something
even without a load. Get the meter.

Neil Jackson wrote:
I've tried that, and nothing seems to be happening. I'm tinkering
a little more. I also read something about a tester with a
60w/6ohm resistor connected between ??purple/orange???
Thank you for the response.
Neil

"Paul Landregan" writes:

are you linking the green wire to ground to activate the PSU? You have
marked it PS-ON?
On my supply this allows me to run anything outside the case.

But do make sure there is an adequate load on the +5 V - an amp or so
should do it (e.g., 5 ohm, 5 W resistor).

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
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contact me, please use the Feedback Form at repairfaq.org. Thanks.

"Neil Jackson" writes:

I do have a meter, When I stopped working last night. I wasn't getting any
reading whatsoever across anything but the main power plug.
I dug up the box it came in, and the box indicates that green is for comm.,
and the unit itself indicate that this is PS-ON.
Do I have to have a load as well as a switched connection?

There should be a reading of a few V between PS-On and ground (green and
black on the mainboard connector. If you don't have this, the internal
fuse has blown or there is some other problem inside the supply.

If there is voltage there, then connecting PS-ON to ground should turn it on.

But make sure you have a load on the +5. At the very least, it may not
work. I've seen them blow up as well without a load.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.

If power supply is plugged in and not powered on, then +5
volts must appear on purple wire. Purple wire would appear
between gray and yellow wires - second wire in from end of
connector.

Purple wire provides voltage to motherboard logic circuits
so that those logic circuits can tell power supply when to
power on and off. No voltage on purple wire means power
supply is internally defective.

No load is required. Only some supplies require a minimal
load on 3.3, 5, or 12 volts - function unique to each power
supply's design. Some supplies are unstable at near zero
load. Power supply without load will not be damaged. But no
voltage on that purple wire means nothing will work.

Neil Jackson wrote:
I do have a meter, When I stopped working last night. I wasn't
getting any reading whatsoever across anything but the main power
plug.
I dug up the box it came in, and the box indicates that green is
for comm., and the unit itself indicate that this is PS-ON.
Do I have to have a load as well as a switched connection?

Thank you
Neil

w_tom writes:

No load is required. Only some supplies require a minimal
load on 3.3, 5, or 12 volts - function unique to each power
supply's design. Some supplies are unstable at near zero
load. Power supply without load will not be damaged. But no
voltage on that purple wire means nothing will work.

I wouldn't be absolutely positive of the bit about no damage being done
if there is no load. I've seen them blow up, though I do not know
for sure that there weren't other problems.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

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contact me, please use the Feedback Form at repairfaq.org. Thanks.

w_tom writes:

If any power supply blows up with or without a load, then
power supply was defective by design. Too many 'cost
controllers' pretend to be computer experts. Therefore many
power supplies are missing essential functions - and even self
destruct.

BTW, every PC power supply must not be damaged even when all
output voltages are shorted together. That is not just a
defacto standard. It is required by specification. Spec even
states how big the shorting wire must be. Shorting a power
supply output will not damage any acceptable power supply.
'No load' will not damage any acceptable power supply. But
too many supplies are purchased only on one specification -
price. 'No specifications' is a common symptom of power
supply failure.

One can always dream. I've seen power supplies from supposedly reputable
well known companies blow up under conditions that were not so extreme.
Even if they are claimed to be short circuit protected, there may be
intermediate levels of overload where bad things happen.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.

Are you sure that the input power is set for 117 v rather than 230 v?

Neil Jackson wrote:

Micro P4ATX 200W (3 Screw SFX)
Switching Power Supply

AC INPUT: 115/230 Vac~ 8/4A

Thank you for all the input guys.
I still need to figure out why the fella had to install current limiters?

Thanks again

Neil
"Mike Berger" wrote in message
...
Are you sure that the input power is set for 117 v rather than 230 v?

Neil Jackson wrote:

Micro P4ATX 200W (3 Screw SFX)
Switching Power Supply

AC INPUT: 115/230 Vac~ 8/4A