Sign in with
Sign up | Sign in
Your question

ground or -DC

Tags:
Last response: in Home Audio
Share
May 8, 2005 5:52:56 AM

Archived from groups: rec.audio.tech (More info?)

I am trying to wire a 24 vdc PSU to an audix 35102 module. The below
link lists the pinouts but I am not quite sure what to do since it
says wire 0 vu to ground. I have a 3 prong AC chord going to the PSU.
The PSU has a + and - for DC. I am thinking I should run the ground of
AC to the chassis which the PSU is in ( theys are in sepparate boxes.
But how do I wire the Modules labeling of 0v and ground? Do I take the
AC ground and wire that to the Module's groung spec? hmm



pinout info:

http://www.vintageking.com/Audix35102.htm

More about : ground

Anonymous
May 8, 2005 11:57:05 AM

Archived from groups: rec.audio.tech (More info?)

cs wrote ...
>I am trying to wire a 24 vdc PSU to an audix 35102 module.
> The below link lists the pinouts but I am not quite sure what
> to do since it says wire 0 vu to ground.

It says to wire pins 10, 11, 41 together and connect them to the
- side of your power supply.

It says to wire pins 22 and 23 together and connect them to the
+ side of your power supply (24VDC).

Is your power supply well filtered, or is it just a wall-wart?
Does it really put out 24VDC, or is that just the nominal rating?
Does the module want well-filtered power, or is it doing its
own final filtereing internally?

> I have a 3 prong AC chord going to the PSU.
> The PSU has a + and - for DC. I am thinking I should run the
> ground of AC to the chassis which the PSU is in ( theys are in
> sepparate boxes.

The electrical codes in most places specify that you connect
the green-wire protective ground to the chassis of the equipment
(assuming it is metal). This is for the safety of people who use
the equipment. This is a good place to get competent assistance
(locally) because your life (and anyone else who touches any
equipment connected to it) is at stake.

If you connect the signal wiring incorrectly you may have a
serious case of hum, but if you get the mains power wiring
wrong, you can have a serious case of dead from electocution.

> But how do I wire the Modules labeling of 0v and ground?
> Do I take the AC ground and wire that to the Module's groung
> spec? hmm

hmm indeed. Now you are asking about shielding and grouding
("screening" and "earthing" to those on the east side of the Pond)
Seems unlikely that anyone can give you a definitive answer at
this distance.

(PS: A "chord" is a cluster of musical notes. A "cord" is an
elecrtrical wire.)
May 8, 2005 11:00:36 PM

Archived from groups: rec.audio.tech (More info?)

Is your power supply well filtered, or is it just a wall-wart?

It is a linear PSU by Power one -2.4 Amps with a Huge 4700uF filter cap

Does it really put out 24VDC, or is that just the nominal rating?

Solid 24vdc

Does the module want well-filtered power, or is it doing its
own final filtereing internally?

I am not sure about this, but they probably have some.

The link above shows 0V(-DC on PSU)-pins 10 and 11 all jumpered to pin
41. My schematic of the Module in question labels pins 10 and 11 as
"0V Supply" and pin 41 as "chassis".

Let me clarify... I am trying to figure If I should run a "true" ground
from AC ground to the module's chassis and all metal surrounding it or
should I just stick with 0V/-DC going to chassis. I've done some work
with guitar effects and the 0V(or - on 9volt supply) is the ground and
shield. I have tested continuity on power supply PSU chassis to what
is labeled -DC and there is no connection when on/off.

Are there advanteges or disadvantages for iether scheme?
which is:
1. Module gound/chassis solely connected to PSU 0V(-DC). here there
is no "true" ground in the same way AC has ground.
or
2. As the link shows( I thhink) AC Ground connected to chassis pin
and jumpered to 0V pins.
Related resources
Can't find your answer ? Ask !
Anonymous
May 9, 2005 12:59:37 AM

Archived from groups: rec.audio.tech (More info?)

<cs@guavatone.com> wrote in message
news:1115604036.229673.149020@g14g2000cwa.googlegroups.com...
> The link above shows 0V(-DC on PSU)-pins 10 and 11 all jumpered to
> pin
> 41. My schematic of the Module in question labels pins 10 and 11 as
> "0V Supply" and pin 41 as "chassis".
>
> Let me clarify... I am trying to figure If I should run a "true"
> ground
> from AC ground to the module's chassis and all metal surrounding it or
> should I just stick with 0V/-DC going to chassis. I've done some work
> with guitar effects and the 0V(or - on 9volt supply) is the ground and
> shield. I have tested continuity on power supply PSU chassis to what
> is labeled -DC and there is no connection when on/off.

I would start by connecting 10&11 to the negative side of the
power supply, and 41 to the chassis (which is also connected
to the green-wire ground from the power cord).

Note that since we know only what you have written here, and
since we don't know how the designers of the module intended
the shielding/grounding to be done, this is only a suggestion. It
may or may not work depending on many factors that we (and
maybe you, too) don't know.

Repeating: Shielding and grounding is nearly as much "art" as
it is "science".

> Are there advanteges or disadvantages for iether scheme?

The major problem you may encounter is a ground loop which
in its simplest form will show up as constant hum.

> which is:
> 1. Module gound/chassis solely connected to PSU 0V(-DC). here there
> is no "true" ground in the same way AC has ground.
> or
> 2. As the link shows( I thhink) AC Ground connected to chassis pin
> and jumpered to 0V pins.

Either of those may be the scheme that works, but I would try
#2 first as it is electrically more safe (tying the module case
to green-wire ground.)

>
May 9, 2005 5:13:25 AM

Archived from groups: rec.audio.tech (More info?)

Thanks for your help. Do you know of any links that discus the
theoretical explanations of 0VDC and ground?

Take care Richard
Anonymous
May 9, 2005 12:29:26 PM

Archived from groups: rec.audio.tech (More info?)

cs@guavatone.com wrote:
> I am trying to wire a 24 vdc PSU to an audix 35102 module.
The below
> link lists the pinouts but I am not quite sure what to do
since it
> says wire 0 vu to ground.


> pinout info:
>
> http://www.vintageking.com/Audix35102.htm

That's not what the source says at all.

It says wire 0 volts (IOW the negative side of the power
supply) to ground.

> I have a 3 prong AC chord going to the PSU.

Actually, that is pretty irrelevant to how the output of the
PSU is connected.

> The PSU has a + and - for DC.

Where's the spec sheet for the PSU?

From what you've said, I don't now whether the - (minus)
output terminal of the PSU is 0 volts or -24 volts.

> I am thinking I should run the ground of AC to the
chassis which the PSU is in ( theys are in separate
> boxes.

If the PSU is in a metal or otherwise conductive box, then
the ground (green) wire of the power cord should indeed be
firmly electrically connected to that metal chassis. The
reason is safety.

> But how do I wire the Modules labeling of 0v and ground?

0 volts means the ground (0 volt) terminal of the PSU. PSUs
like yours might have a - (minus) output that is
actually -24 volts. Or, the minus output can be 0 volts AKA
ground.

If the PSU has a -24 volt output, then there will also be a
0 volt or ground output as well. In your application,
the -24 volt PSU output if it exists, should be insulated
and connected to nothing.

> Do I take the AC ground and wire that to the Module's
grouns spec? hmm

I'll bet you didn't mean that "hmm" to mean humming from the
output of your project. But, if you do things wrong you
might end up with hum, or worse yet a damaged module. If
your PSU has a -24 volt output and you confuse it with
ground, then the results could be the application of 48
volts to the module. Probably not a pretty picture! ;-(

If you get the feeling that you're over your head, hold that
thought until you thoroughly understand what you are doing!
Anonymous
May 9, 2005 1:36:40 PM

Archived from groups: rec.audio.tech (More info?)

<cs@guavatone.com> wrote ...
> Thanks for your help. Do you know of any links that discus
> the theoretical explanations of 0VDC and ground?

"0VDC" is a non-standard and not very technical term, at least
the way you are using it. Many (most?) of us who have decades
of experience wiring things like this are confused by your term.
Arny's question about ground vs. negative is valid as we don't
really know if you have a simple single-ended 24VDC supply
or a +/- 24VDC bipolar supply.

If what you are asking is how to handle safety grounds, that
is one question. There are many online discussions of how
to handle green-wire safety grounds for mains/power wiring.
Note that this is a tricky area as it may require design by an
accredited engineer in some places, and it is always a significant
safety issue.

If you are asking about shielding and grounding (of signals)
that is a very different (but somewhat related) question.

I know that shielding and grounding is discussed in the website
www.epanorama.net and quite likely safety grounding is also
discussed there. There are many others out there also.
Anonymous
May 10, 2005 3:00:09 AM

Archived from groups: rec.audio.tech (More info?)

<cs@guavatone.com> wrote in message
news:1115626405.518849.98470@z14g2000cwz.googlegroups.com...
> Thanks for your help. Do you know of any links that discus the
> theoretical explanations of 0VDC and ground?
>
> Take care Richard

Not much to discuss. In both single and bipolar power supply devices 0v is
the reference point for any signals.

Metal chassis in all but double-insulated devices must be grounded. Signal
ground (and power supply 0v) may be direcly connected to the chassis ground,
or maybe resistively distanced from the chassis ground if 'ground loops' are
a problem. Signal ground is usually grounded to aid shunting of 'screened
interference signal to, um, ground.

geoff
May 10, 2005 4:40:05 AM

Archived from groups: rec.audio.tech (More info?)

What does IOW stand for?

Sorry guys-
It is a single ended 24VDC power one PSU # HC24-2.4-A

http://www.power-one.com/resources/products/datasheet/l...

grouns spec? hmm


I'll bet you didn't mean that "hmm" to mean humming from the
output of your project.


I meant "hmmm" as in thinking. Yeah I can understand your concern.
What is baffling me is Theory. EG.... I thought in a single ended PSU,
that +24VDC exist in it reference to 0VDC and if AC ground is
connecterd to 0VDC then the reference is would be comprimised.


Thanks,
Anonymous
May 10, 2005 9:02:49 AM

Archived from groups: rec.audio.tech (More info?)

<cs@guavatone.com> wrote ...
> What does IOW stand for?

In Other Words. Lists of internet abbreviations are available
in many places online. Google is your friend.

> Sorry guys-
> It is a single ended 24VDC power one PSU # HC24-2.4-A
> http://www.power-one.com/resources/products/datasheet/l...
> grouns spec? hmm
>
> I'll bet you didn't mean that "hmm" to mean humming from the
> output of your project.
>
> I meant "hmmm" as in thinking. Yeah I can understand your concern.
> What is baffling me is Theory. EG.... I thought in a single ended
> PSU,
> that +24VDC exist in it reference to 0VDC and if AC ground is
> connecterd to 0VDC then the reference is would be comprimised.

Voltage is relative. "0VDC" is meaningless and ambitguous.
You have a single-ended DC power supply where the - side
is tied to circuit ground. That is what the module needs to operate.
If you had a couple of 12V batteries you could connect them
in series to run the unit without regard to what is "ground".

Now when you introduce AC power, you have the complication
of not only AC (which is a source of noise), but also a potentially
lethal current that needs extra measures to protect users from
electrocution. The simplest way of doing this is to make a
device that has no exposed metal parts. Or something that is
"double-insulated".

But these methods don't really work very well for audio equipment,
so the most common method of protection is to use a 3-wire power
cable and to tie the green-wire safety ground to the metal chassis.
This is required by law in most jurisdictions.

It is when you tie the AC power safety ground to the same point
as the DC return (ground), and the signal shield (if balanced)
and/or return (if unbalanced) that you start running into potential
problems with ground-loops, powerline-induced noise, etc. And
then there is protection from RF fields which may be helped (or
not) by green-wire safety ground.

No, tying the DC ground/reference to the AC safety ground does
not "compromise" the reference in the sense that I think you are
using the word. But it does introduce complications because of
the connection to the "outside world". Doing this right requires
either knowledge of how the module is wired, or trial-and-error
to get the shielding and grounding worked out properly.

A first-cut assumption is that they want the signal ground and DC
return (- side of the power supply) tied to pin 10&11, and the
case and AC power green-wire ground tied to pin 41. Presumably
their pin 10&11 and pin 41 are tied together inside the module
at the magic point where it will cause the least interference. But
I wouldn't bet my life on it.
Anonymous
May 11, 2005 1:53:52 AM

Archived from groups: rec.audio.tech (More info?)

<cs@guavatone.com> wrote in message
news:1115710805.217931.21210@f14g2000cwb.googlegroups.com...

>
> I meant "hmmm" as in thinking. Yeah I can understand your concern.
> What is baffling me is Theory. EG.... I thought in a single ended PSU,
> that +24VDC exist in it reference to 0VDC and if AC ground is
> connecterd to 0VDC then the reference is would be comprimised.

No. The DC is isolated from the ac side by a transformer. You could
equally designate the +24v "0v" (and optionally connect it to mains ground)
and then the other side would become "-24V".

geoff
!