Archived from groups: alt.comp.periphs.mainboard.tyan (
More info?)
"roger haugen" <npatriot@online.no> wrote:
>trick it with the green and any black on the biggest plug
It takes more than that. At least the 5VDC bus must have a
minimum load, and on large 400W+ power supplies that may be as
high as 5 to 10 Amps, which is not trivial. While once upon a
time it was possible to test a power supply by simply connecting
a hard disk to provide a load, that is no longer true.
Essentially, there is little point in a Rube Goldberg lashup to
see if the fan makes noise. It doesn't. Regardless, here's a
the proceedure for testing ATX power supplies. This assumes a
20-pin plug (the colors would be the same, but see below for a
24-pin plug pinout).
1) Plug AC in.
2) Measure pin 9 (Purple wire). Should show about 5.0 vdc.
3) Measure pin 14 (Green wire). Should show some voltage
between 3.5 and 5 vdc. The exact voltage is not critical.
4) Unplug AC.
5) Put a load across the 5 vdc line. With a small supply you
can do this using an old disk drive, cdrom, or a resistor.
With large supplies it may require a load of 5 to 10 Amps
(A 1 Ohm resistor would draw 5 Amps. The power rating would
need to be at least 2 times the power to be dissipated.)
6) Jumper pin 14 (Green wire) to ground (any Black wire).
7) Plug AC in.
8) A. The fan should run.
B. All voltages should measure close to their
nominal values (Note that -5v and -12v may be
very poorly regulated).
Note that pin 14 is the PS-ON signal line, which is normally
wired to the on/off switching circuit on the motherboard. It
has a 1000 ohm pull-up resistor connected (internal to the PSU)
to the +5v Standby line, and if there is no other connection it
should probably read close to 5 volts. That voltage will cause
the power supply to be "off". The nominal switching point for
PS-ON is 0.8vdc, and standard operating voltages are less than
0.4 volts for "on" and more than 3.5 volts for "off".
Here is a list of leads on a 20 pin connector,
PIN COLOR NAME DESCRIPTION
------------------------------------
1 Orange +3.3V Power, +3.3V
2 Orange +3.3V Power, +3.3V
3 Black GND Ground
4 Red +5V Power, +5V
5 Black GND Ground
6 Red +5V Power, +5V
7 Black GND Ground
8 Gray PWR-OK Power OK
9 Purple +5V VSB +5V VSB
10 Yellow +12V Power, +12V
11 Orange +3.3V Power, +3.3V
12 Blue -12V Power, -12V
13 Black GND Ground
14 Green PS-ON PS Remote on/off
15 Black GND Ground
16 Black GND Ground
17 Black GND Ground
18 White -5V Power, -5V
19 Red +5V Power, +5V
20 Red +5V Power, +5V
And this is a list of leads on a 24 pin connector,
PIN COLOR NAME DESCRIPTION
------------------------------------
1 Orange +3.3V Power, +3.3V
2 Orange +3.3V Power, +3.3V
3 Black GND Ground
4 Red +5V Power, +5V
5 Black GND Ground
6 Red +5V Power, +5V
7 Black GND Ground
8 Gray PWR-OK Power OK
9 Purple +5V VSB +5V VSB
10 Yellow +12V Power, +12V
11 Yellow +12V Power, +12V
12 Orange +3.3V Power, +3.3V
13 Orange +3.3V Power, +3.3V
14 Blue -12V Power, -12V
15 Black GND Ground
16 Green PS-ON PS Remote on/off
17 Black GND Ground
18 Black GND Ground
19 Black GND Ground
20 White -5V Power, -5V
21 Red +5V Power, +5V
22 Red +5V Power, +5V
23 Red +5V Power, +5V
24 Black GND Ground
The -5 VDC line may not exist.
The +5 VSB supply is Standby Power, which supplys parts of the
motherboard which are always powered up (to allow options like
"wake-on ..." to work).
The PWR-OK line is at ~5 VDC if the AC input and the +5V and
+12V lines are within specifications. If either the +5V or the
+12V line falls to below the specified voltage tolerance or if
AC is lost for more than one power cycle interval, then PWR-OK,
will drop to ~0 VDC. (If it helps any, if AC is lost, PWR-OK is
supposed to drop at least 1 ms before the +5V and +12V lines go
below specified voltage tolerances!)
>"dr ratt" <spamsum1else@zen.co.uk> wrote:
>> "Eric" <say.no@spam.now> wrote:
>> > >
>> > > I just got a new Antec 550 and wanted to hear how loud it was so I
>> > > plugged it in, turned it on and it didnt come on. I dont have anything
>> > > hooked to it yet. I just wanted to hear it first. Is it okay? Does it
>> > > neesd to be plugged into a motherboard first?
>> > >
>> > > Just checking to make sure I didnt get a bad PS.
>> > >
>> > > Thanks!
>> >
>> > PC Power & Cooling sells a power supply tester which plugs into the ATX connector
>> >
http://www.pcpowerandcooling.com/products/cooling/tester/index.htm
>> >
>> > I've never used this unit so I can't provide any further information.
>> >
>> > Eric
>>
>> yes it needs plugging in as it's not supposed to come on until the button on
>> the case front is pressed. there is a way to fool the psu that it is plugged
>> in but you shouldn't mess with that if you don't understand what you're
>> doing. just plug it in. you'll find it fairly unobtrusive in use.
--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@barrow.com