Hi,
need help hooking head unit up to psu to check if its still working,
can't figure out how to turn on the power supply.
thanks

AT or ATX power supply?

On Thu, 10 Feb 2005, Brett wrote:

Hi,
need help hooking head unit up to psu to check if its still working,
can't figure out how to turn on the power supply.
thanks

ATX

read somewhere if i connect a 12V bulb to the +5V and the Ground it should
work

"MZ" wrote in message
...
AT or ATX power supply?

On Thu, 10 Feb 2005, Brett wrote:

Hi,
need help hooking head unit up to psu to check if its still working,
can't figure out how to turn on the power supply.
thanks

In article ,
"Brett" wrote:

Hi,
need help hooking head unit up to psu to check if its still working,
can't figure out how to turn on the power supply.
thanks

That may or may not work. Switching power supplies are unstable by
nature so they don't handle some kinds of loads well. It would be
better to buy a 12V switching power supply made for hobby use. These
have current limiting rather than shutdown and they handle varying loads
fairly well. $50 will get you 11A continuous, $35 is good for 6A.

Here ya go buddy.
http://www.duxcw.com/faq/ps/ps4.htm

that'll show you how to turn it on, you just need to short two of the leads.


--hatebreeder

Kevin McMurtrie wrote:
In article ,
"Brett" wrote:


Hi,
need help hooking head unit up to psu to check if its still working,
can't figure out how to turn on the power supply.
thanks


That may or may not work. Switching power supplies are unstable by
nature so they don't handle some kinds of loads well. It would be
better to buy a 12V switching power supply made for hobby use. These
have current limiting rather than shutdown and they handle varying loads
fairly well. $50 will get you 11A continuous, $35 is good for 6A.

thanks for that...
guess the atx unit i got off my mate isn't working, can't get the fan going
he said he wasn't sure if this one was dead or not.


"anon" wrote in message
...
Here ya go buddy.
http://www.duxcw.com/faq/ps/ps4.htm

that'll show you how to turn it on, you just need to short two of the
leads.


--hatebreeder

Kevin McMurtrie wrote:
In article ,
"Brett" wrote:


Hi,
need help hooking head unit up to psu to check if its still working,
can't figure out how to turn on the power supply.
thanks


That may or may not work. Switching power supplies are unstable by
nature so they don't handle some kinds of loads well. It would be
better to buy a 12V switching power supply made for hobby use. These
have current limiting rather than shutdown and they handle varying loads
fairly well. $50 will get you 11A continuous, $35 is good for 6A.

Got the HU running which is great, is there any hope of using the PSU to
power the head unit and some speakers as well.

At 12V it says its max output is 18A

On Fri, 11 Feb 2005 13:16:53 +1100, "Brett"
wrote:

Got the HU running which is great, is there any hope of using the PSU to
power the head unit and some speakers as well.


What's the problem?

Just hookup the speakers to the HU's speakers' outs or if u have an
external amp, hook that up too.

U know u can only check for functionality. The speakers will most
likely sound different inside the car.

On Thu, 10 Feb 2005 18:52:19 -0800, bobb wrote:

On Fri, 11 Feb 2005 13:16:53 +1100, "Brett"
wrote:

Got the HU running which is great, is there any hope of using the PSU to
power the head unit and some speakers as well.


What's the problem?

Just hookup the speakers to the HU's speakers' outs or if u have an
external amp, hook that up too.

U know u can only check for functionality. The speakers will most
likely sound different inside the car.



Most computer power supplies won't turn on unless there's a big enough
current draw on them to activate them. If you connect a PC power
supply unit to a motherboard to test it, the PS usually won't even
turn on unless you have the CPU, memory, AND a video card installed in
the motherboard. You may also have to have a current draw on both the
+12V and +5V lines to get the PS to turn on.

I'd either hook up a light bulb or a power resistor to the +5V lines,
and connect the head unit to the +12V lines. That should be enough to
get the power supply to turn on. If you can get 18A out of the 12V
lines, that's over 200 Watts power capacity, which should be plenty,
even assuming a 50% efficiency for the head unit.

Scott Gardner

"Most computer power supplies won't turn on unless there's a big enough
current draw on them to activate them. If you connect a PC power
supply unit to a motherboard to test it, the PS usually won't even
turn on unless you have the CPU, memory, AND a video card installed in
the motherboard"

Where the hell did you come up with that ****??

A PC power supply will turn on regardless of how much power is being drawn
from it. You can start a computer with only the motherboard hooked up, it
just won't do much but it wil start.



"Scott Gardner" wrote in message
...
On Thu, 10 Feb 2005 18:52:19 -0800, bobb wrote:

On Fri, 11 Feb 2005 13:16:53 +1100, "Brett"
wrote:

Got the HU running which is great, is there any hope of using the PSU to
power the head unit and some speakers as well.


What's the problem?

Just hookup the speakers to the HU's speakers' outs or if u have an
external amp, hook that up too.

U know u can only check for functionality. The speakers will most
likely sound different inside the car.



Most computer power supplies won't turn on unless there's a big enough
current draw on them to activate them. If you connect a PC power
supply unit to a motherboard to test it, the PS usually won't even
turn on unless you have the CPU, memory, AND a video card installed in
the motherboard. You may also have to have a current draw on both the
+12V and +5V lines to get the PS to turn on.

I'd either hook up a light bulb or a power resistor to the +5V lines,
and connect the head unit to the +12V lines. That should be enough to
get the power supply to turn on. If you can get 18A out of the 12V
lines, that's over 200 Watts power capacity, which should be plenty,
even assuming a 50% efficiency for the head unit.

Scott Gardner

On Fri, 11 Feb 2005 16:17:27 +1300, "Sponge" wrote:

"Most computer power supplies won't turn on unless there's a big enough
current draw on them to activate them. If you connect a PC power
supply unit to a motherboard to test it, the PS usually won't even
turn on unless you have the CPU, memory, AND a video card installed in
the motherboard"

Where the hell did you come up with that ****??

A PC power supply will turn on regardless of how much power is being drawn
from it. You can start a computer with only the motherboard hooked up, it
just won't do much but it wil start.





I guess it's changed with the newer ATX power supplies - most of my
experience was with the older AT power supplies, which behaved as I
described. If you only connected up a motherboard without a video
card, or if you just connected a drive and nothing else, when you
pressed the power switch, the power supply fan woudn't spin, and it
wouldn't put out any power. With the ATX supplies, I guess the
turn-on signal lead from the PS and the feedback lead from the
motherboard allow the power supply to get started without a particular
load applied.

If he's got an ATX power supply that he wants to use without a
motherboard connected to it, there's a wire that he'll have to short
to ground to get the power supply to turn on. Here's a link to a page
describing the steps"

http://www.bluemax.net/techtips/ATXP...pplyWiring.htm

Scott Gardner

Ok, that link has some useful information about ATX PSU's but you are still
wrong about AT PSU's.

I have had many many AT PSU's not hooked up to any components and had them
power up when pushing the switch.


"Scott Gardner" wrote in message
...
On Fri, 11 Feb 2005 16:17:27 +1300, "Sponge" wrote:

"Most computer power supplies won't turn on unless there's a big enough
current draw on them to activate them. If you connect a PC power
supply unit to a motherboard to test it, the PS usually won't even
turn on unless you have the CPU, memory, AND a video card installed in
the motherboard"

Where the hell did you come up with that ****??

A PC power supply will turn on regardless of how much power is being
drawn
from it. You can start a computer with only the motherboard hooked up, it
just won't do much but it wil start.





I guess it's changed with the newer ATX power supplies - most of my
experience was with the older AT power supplies, which behaved as I
described. If you only connected up a motherboard without a video
card, or if you just connected a drive and nothing else, when you
pressed the power switch, the power supply fan woudn't spin, and it
wouldn't put out any power. With the ATX supplies, I guess the
turn-on signal lead from the PS and the feedback lead from the
motherboard allow the power supply to get started without a particular
load applied.

If he's got an ATX power supply that he wants to use without a
motherboard connected to it, there's a wire that he'll have to short
to ground to get the power supply to turn on. Here's a link to a page
describing the steps"


http://www.bluemax.net/techtips/ATXP...pplyWiring.htm

Scott Gardner

On Fri, 11 Feb 2005 17:33:52 +1300, "Sponge" wrote:

Ok, that link has some useful information about ATX PSU's but you are still
wrong about AT PSU's.

I have had many many AT PSU's not hooked up to any components and had them
power up when pushing the switch.




Maybe we used different brands of PSU's - I don't know. But I built a
bunch for myself, and I worked at a shop building PC's, and if I
didn't plug anything into the power supply, and I turned the switch
on, the fan wouldn't come on or anything. Same if I just connected a
motherboard, CPU, and RAM. No indicator lights on the PS or mobo, no
fan motion, nothing. Usually, I had to connect mobo, CPU, RAM, and at
least one ISA card before the power supply would light off.

I can't say that every power supply worked the same way, but I never
had an AT power supply that would even spin up the fan if I took it
out of the box, plugged it into the wall outlet, and pressed the power
button without connecting a load to it.

Google around on it - I'm not the only person to have noticed this.
Anway, since the ATX units don't behave this way, it's neither here
nor there for the original poster's application.

Scott Gardner

Every AT supply I've ever used has powered on with nothing attached.

"Scott Gardner" wrote in message
...
On Fri, 11 Feb 2005 17:33:52 +1300, "Sponge" wrote:

Ok, that link has some useful information about ATX PSU's but you are
still
wrong about AT PSU's.

I have had many many AT PSU's not hooked up to any components and had them
power up when pushing the switch.




Maybe we used different brands of PSU's - I don't know. But I built a
bunch for myself, and I worked at a shop building PC's, and if I
didn't plug anything into the power supply, and I turned the switch
on, the fan wouldn't come on or anything. Same if I just connected a
motherboard, CPU, and RAM. No indicator lights on the PS or mobo, no
fan motion, nothing. Usually, I had to connect mobo, CPU, RAM, and at
least one ISA card before the power supply would light off.

I can't say that every power supply worked the same way, but I never
had an AT power supply that would even spin up the fan if I took it
out of the box, plugged it into the wall outlet, and pressed the power
button without connecting a load to it.

Google around on it - I'm not the only person to have noticed this.
Anway, since the ATX units don't behave this way, it's neither here
nor there for the original poster's application.

Scott Gardner

In article ,
"Sponge" wrote:

"Most computer power supplies won't turn on unless there's a big enough
current draw on them to activate them. If you connect a PC power
supply unit to a motherboard to test it, the PS usually won't even
turn on unless you have the CPU, memory, AND a video card installed in
the motherboard"

Where the hell did you come up with that ****??

A PC power supply will turn on regardless of how much power is being drawn
from it. You can start a computer with only the motherboard hooked up, it
just won't do much but it wil start.

The deal is that some switching power supplies have multiple voltages
drawn off a single PWM (pulse-width-modulator) driving a multi-winding
transformer. One primary DC output is regulated via feedback to the PWM
while the secondary DC outputs are regulated using magnetic amplifiers.
The current available on the secondary outputs is proportional to the
current drawn on the primary output. With no load on the primary, the
PWM and transformer have almost no power flowing through them to drive
the secondary outputs.

In the case of smaller computer power supplies, +5VDC is the primary
that gives feedback to the PWM. It has to be loaded to make the
secondary 12V output work. Larger computer power supplies have multiple
circuits like 3.3V primary with 5V secondary and 12V primary with -12V
and -5V secondary. In that case you can draw +12V without needing to
load other outputs.

Speaking of multiple outputs, many computer power supplies do not have
overload protection on individual outputs. A dead short or exceeding
the total wattage limit will shut it down but drawing too much power on
a single line can cause it to burn out.

All of this mess is why it's better to buy a hobby grade power supply.

Well crap - maybe we just used weird power supplies where I worked.
If I hadn't found so many other references to the same thing on
Google, I'd think I was losing my mind. This was also back in 1990
and 1991, but I doubt power supplies changed much between then and
whenever ATX became the new standard.

Scott Gardner



On Thu, 10 Feb 2005 23:52:00 -0500, "MZ"
wrote:

Every AT supply I've ever used has powered on with nothing attached.

"Scott Gardner" wrote in message
.. .
On Fri, 11 Feb 2005 17:33:52 +1300, "Sponge" wrote:

Ok, that link has some useful information about ATX PSU's but you are
still
wrong about AT PSU's.

I have had many many AT PSU's not hooked up to any components and had them
power up when pushing the switch.




Maybe we used different brands of PSU's - I don't know. But I built a
bunch for myself, and I worked at a shop building PC's, and if I
didn't plug anything into the power supply, and I turned the switch
on, the fan wouldn't come on or anything. Same if I just connected a
motherboard, CPU, and RAM. No indicator lights on the PS or mobo, no
fan motion, nothing. Usually, I had to connect mobo, CPU, RAM, and at
least one ISA card before the power supply would light off.

I can't say that every power supply worked the same way, but I never
had an AT power supply that would even spin up the fan if I took it
out of the box, plugged it into the wall outlet, and pressed the power
button without connecting a load to it.

Google around on it - I'm not the only person to have noticed this.
Anway, since the ATX units don't behave this way, it's neither here
nor there for the original poster's application.

Scott Gardner

"Scott Gardner" wrote in message
...
Well crap - maybe we just used weird power supplies where I worked.
If I hadn't found so many other references to the same thing on
Google, I'd think I was losing my mind. This was also back in 1990
and 1991, but I doubt power supplies changed much between then and
whenever ATX became the new standard.

Scott Gardner




Scott,

That used to be the way, SMPS's blow up with no loading, big time! Newer
power supplies have built in loading to ensure reliability. Most new ones
will come up with no load, old ones will not. On the old ones it's just the
protection system keeping it from exploding.

I tend to believe this is because there are more and more amatuer builders
and sometimes forget to shut off the PSU assuming the software shut down has
done the trick. One then pulls the PS connection and the PSU goes back for
warranty replacement.

I like it, a few external components and you have a cheap bench supply,
especially for high current 5V stuff.

Chad

could you stop it from burning out by putting an in-line fuse in place?
since you can restrict how much current will be drawn?

got everything hooked up the head unit works, found out i'd left a cd in it
so thats where that one went.

On this ATX model all I had to do was ground the ps_on a green wire. For
some others sometimes they do need a load across the +5V, well that's what i
had read after some google searching.

Those hobby units are pretty expensive, and I was able to just get a spare
psu from old computer.

"Kevin McMurtrie" wrote in message
...
In article ,
"Sponge" wrote:

"Most computer power supplies won't turn on unless there's a big enough
current draw on them to activate them. If you connect a PC power
supply unit to a motherboard to test it, the PS usually won't even
turn on unless you have the CPU, memory, AND a video card installed in
the motherboard"

Where the hell did you come up with that ****??

A PC power supply will turn on regardless of how much power is being
drawn
from it. You can start a computer with only the motherboard hooked up,
it
just won't do much but it wil start.

The deal is that some switching power supplies have multiple voltages
drawn off a single PWM (pulse-width-modulator) driving a multi-winding
transformer. One primary DC output is regulated via feedback to the PWM
while the secondary DC outputs are regulated using magnetic amplifiers.
The current available on the secondary outputs is proportional to the
current drawn on the primary output. With no load on the primary, the
PWM and transformer have almost no power flowing through them to drive
the secondary outputs.

In the case of smaller computer power supplies, +5VDC is the primary
that gives feedback to the PWM. It has to be loaded to make the
secondary 12V output work. Larger computer power supplies have multiple
circuits like 3.3V primary with 5V secondary and 12V primary with -12V
and -5V secondary. In that case you can draw +12V without needing to
load other outputs.

Speaking of multiple outputs, many computer power supplies do not have
overload protection on individual outputs. A dead short or exceeding
the total wattage limit will shut it down but drawing too much power on
a single line can cause it to burn out.

All of this mess is why it's better to buy a hobby grade power supply.