[Scott Dorsey]

hank alrich wrote:
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?

The _input_ caps before the transformer are more likely to be the problem,
unless this is a hot chassis unit with a switching supply in which case
all bets are off.

I am ASSUMING that you are seeing this voltage with nothing plugged into
the receiver, because the cable TV and satellite systems are prime sources
for induced noise.

2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

This is normal. SOME of it may be on the feed itself. Use a pair of
headphones and connect it to one of the RCA audio feeds and see if you
hear the hum. Also look for hum bars on the video.

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".

You don't need the MIO or anything but a pair of headphones with an RCA
adaptor. Headphones are the most powerful debugging tool you have available
to you because they allow you to listen to a line-level signal without any
possibility of introducing additional ground loops.

I cheerfully and gratefully solicit advice and commentary. At this point
they cannot feed audio from the video receivers into the house speaker
system driven by the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm figuring they
need to replace the Onkyo, for starters, but I'm not convinced that's
going to take care of the video-related audio noise problem.

If you don't hear it on headphones and there are no hum bars on the video,
use audio isolation transformers between the receiver and the video system.

If you hear it on headphones and see noise on the video, it's time to start
tearing the satellite system and the video distribution system coming out of
it apart.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Richard Crowley]

"hank alrich" wrote ...
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Do any of the units have 3-prong power plugs/cables? Or 2-prong?
Exactly where/how are these plugged into the source of power?
Are they all running from a power strip? Or more than one?
Is everything on the same branch circuit (breaker)?
How new/reliable is the building wiring?
How good are the green-wire grounds?

What are the startup and warm-up chassis voltages relative to
green-wire ground? Else you are only measuring the differential
between reciever and CD player, etc. which is the equivalent of
one equation and two unknowns. We don't know which unit is
behaving badly (or perhaps both).

Does the system hum with an isolated source (an MP3 player, etc.)?
What is the chassis voltage of the receiver with nothing attached?
(relative to green-wire ground)
Does it change with the speaker lines connected?

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?

Filter caps in the power supply should have NO effect on the
chassis voltage. Regardless of how bad they are or what temp.
If they do, something is seriously wacko (perhaps dangerous?)
Certainly bad filter caps will contribute to hum in the system,
but you should NOT see any of it at the chassis ground point.

2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

Normally one would see zero volts between the chassis of the
various components. Audible hum could have other sources than
differential ground potentials.

Does the receiver hum with no inputs connected?
What is the receiver chassis voltage relative to green-wire gnd?

Classic case of disconnect everything and then restore it one
connection at a time and see the effect of each individual
connection.

While everything is disconnected, measure each chassis
voltage against a common reference (mains green-wire gnd)

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".

What do the isolated outputs of the satellite receivers sound
like by themselves (on headphones, etc.)?
What is the chassis voltage of the sattelite recievers (each
of them isolated) relative to green-wire ground?

There is a standardized way of testing the safety of the exposed
metal parts of equipment. I will look up the details when I get
home. IIRC, it is a resistor and a capacitor and a multimeter.
I didn't find anything online. Likely using the wrong search term.

Is the RF feed from the satellite dish(es) grounded at any
other point? Frequently there is a "grounding block" before
the coax enters the building. This is supposed to be connected
with a stout wire to a physical ground (water pipe, etc.) as a
primary protection against lightning/static entering via the
sattelite dish cable. If the grounding blocks are connected
to some kind of ground that is different than the ground used
by the electrical power system in the building, that could be
a source of significant ground potentials right there. This is
frequently a problem with cable systems, also where the
cable system's notion of ground isn't necessarily the same
as the power mains.


Iraq is Arabic for Vietnam

Democrat is Arabic for victim
Progressive is Arabic for infidel

[Chris Hornbeck]

On Thu, 15 Mar 2007 16:54:49 -0800, (hank alrich)
wrote:

I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

Do the sat receivers have *video* lines run out to the various TV's,
or is the picture run over, for example, channel 3?

In either case, a good first troubleshooting step might be to
disconnect all of the video feeds. If the hum goes away, you
know you have ground loop issues. If it doesn't, you may still
have ground loop issues, but it won't be *those* ground loops.

I tend to think that the CD changer issue might be a blind
alley, but does disconnecting it from the system remove the
hum from the sat receivers?

FWIW, sat dishes and their downfeed are potentially the worst
case ground loop issue; Code (almost universally ignored, but
there are Boy Scouts) requires Earthing before entering the
building; DC power must pass up the downfeed; no "ground
lift" is (practically) possible. Just an aside; sorry.

All good fortune, and much thanks, as always,

Chris Hornbeck

[hank alrich]

I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?


2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".


I cheerfully and gratefully solicit advice and commentary. At this point
they cannot feed audio from the video receivers into the house speaker
system driven by the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm figuring they
need to replace the Onkyo, for starters, but I'm not convinced that's
going to take care of the video-related audio noise problem.

--
ha
Iraq is Arabic for Vietnam

[Les Cargill]

hank alrich wrote:

I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?


Can you quickly sub out the Onkyo and see? What is the real ground here;
gotta find the *real* ground. If you have 12 VMRS worth of nonground,
be especially skeptical of that. What's the safety leg of the three
prong in the wall say, relative to, say, a ground rod? Are all the
outlets good? Is there a Dranitz meter in the county? No, strike that.

Did you run an outlet tester on all potentially interesting outlets?

Visualize Shelly Berman saying "University of Chicago" and "relative
to what". At least that always helps me...



2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.

How are the grounds on each?

Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.


It's probably inband then, unless the Onkyo has secret desires
to be an AC power supply. Wait, didn't... never mind.

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".


A single amplifiction element above reproach is all you need
to find out. Mackie 1202, headphones. Yes? Audit carefully
it's power supply first. I use an old Tascam cassette deck;
it doesn't care *what* comes out of the wall, it cheerfully
ignores pretty much all powerline noise no matter what.


I cheerfully and gratefully solicit advice and commentary. At this point
they cannot feed audio from the video receivers into the house speaker
system driven by the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm figuring they
need to replace the Onkyo, for starters, but I'm not convinced that's
going to take care of the video-related audio noise problem.


Start from the walls and move in. Trust nothing! Good luck!


--
Les Cargill

[Arny Krueger]

"hank alrich" wrote in message


I'm helping folks who have a sports bar get some of their
audio action working better. Following info from RAP in
other ground problem threads I've determined that the
ground is good and that the AC to the closet with the CD
changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the
Onkyo receiver in that about 3.5 volts is showing between
the chassis of the CD player and the receiver (probing at
the ground collars of their respective RCA connectors)
when the system is first started cold after being
turned-off overnight.

Please tell me this *isn't* true when the RCA cable is hooked up. If it was,
then the cable would obviously be bad. ;-)

If you have two components with essentially floating chassis, and you
measure the ground potentional with a Hi-Z meter, you're probably measuring
a voltage that involves a miniscule amount of current. Try it at home.

That miniscule current might be due to stray capacitance (AC wiring, power
transformer) and any small-value powerline RF fliter caps in the equipment,
which are wired between the power line and the chassis ground.

As it warms up that rises, to as
much as 12 volts. When the CD player AC power was sourced
from an outlet on the back of the receiver I measured
10.5 volts at cold start, and lord only knows what it
must have been after warming up. When I hooked the CD
changer's AC cable to the same power strip feeding the
rest of the gear in the closet the voltage dropped to 3.5
cold.

If you're ambitious, hook a 10 ohm resistor between the two RCA jack
collars, and measure the difference again. I'll bet the voltage is very
close to zero. Bottom line, this voltage reading is not the source of any
problems, because when you hook the RCA cable up, it goes down to some even
lower miniscule voltage. Reducing this voltage to next to nothing is why
there are collars on RCA jacks and two conductors in each channel's RCA
cable!

Is this a sign that the power supply filter caps in the
receiver are leaking, and leaking more as they heat?

If by power supply filter caps you mean the ca. 0.01 uF 600 volt ceramics
that are sometimes connected from one side of the power line to the chassis,
then probably not. By definition their leakage is waaay low. OTOH their
impedance at 60 Hz while high, is low enough to allow some AC current to
flow through.

If by power supply filter caps you the electrolytics in the power supply,
then no way. This voltage you're measuring is probably leakage through
insulation whose resistance is many meghoms, but is not a perfect open
circuit, and some honest-to-goodness AC current that is passing through any
small value (for 60 Hz) bypass caps on the power line wiring.

2. There is a ridiculous amount of hum coming via the
audio feeds from the DishNet video recievers, fed to the
Onkyo receivers audio inputs. Yet there is no comparably
appreciable voltage showing between those chassis;
measuring again RCA's-to-RCA's I see single-digit
millivolts.

Welcome to the wonderful world of antenna-driven ground loops and their
effects on unblanced audio lines . That satellite equipment is hopefully
grounded like there's no tomorrow. Lightning strikes and all that.

Remember that $20 Radio Shack stereo audio isolation tranformer that I
tested and worked so good? That's one easy solution.

Plan B is to use a coax cable RF isolation transformer to accomplish the
same goal on the antenna side. But then you're on the hook for any problems
with Satellite reception down the road.

Plan C is to eliminate the earth grounding for the audio equipment. That's
probably very ugly.

I plan to go back with the MIO and feed audio from the
video receivers to SpectraFoo to see if noise associated
with those audio feeds is actually being delivered along
with the intended audio, i.e., if that hum is not simply
inter-component ground related, but part of the "signal".

I'd stop off at the nearest Radio Shack and pick up one or more of those
little audio isolation transformers, which come with RCA connectors already
attached. Just make sure there's no sex problems with the RCA connectors.

If you're on a cost-plus contract and you've got some time, order up
Jensen's version of the same thing. It costs about 10 times as much and
might even sound a little better, or not. Remember, this is TV audio which
is already crapped-on more times than you can count.

But, there's more profit margin in the Jensen, and it will look so cool. It
will make you memorable to every knowlegable person who looks at the TV
audio side of the sound system of this high fallutin' salon you're working
in. ;-)

I cheerfully and gratefully solicit advice and
commentary. At this point they cannot feed audio from the
video receivers into the house speaker system driven by
the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm
figuring they need to replace the Onkyo, for starters,
but I'm not convinced that's going to take care of the
video-related audio noise problem.

Thanks for the reminder of how sweet it is when one can solve grounding
problems with balanced I/O and fiber optic digital audio links.

[[email protected]]

On Mar 15, 4:54 pm, (hank alrich) wrote:
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?

2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".

I cheerfully and gratefully solicit advice and commentary. At this point
they cannot feed audio from the video receivers into the house speaker
system driven by the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm figuring they
need to replace the Onkyo, for starters, but I'm not convinced that's
going to take care of the video-related audio noise problem.

--
ha
Iraq is Arabic for Vietnam

Hank,

Here are some additional items you might find useful:

1) Ebtech Hum-Eliminator - cheap transformer just to break signal DC
paths for diagnostics
2) portable, battery operated player like an iPod to test inputs
without ground issues
3) headphones like Scott says to listen to feeds

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com

[Scott Dorsey]

hank alrich wrote:

This is normal. SOME of it may be on the feed itself. Use a pair of
headphones and connect it to one of the RCA audio feeds and see if you
hear the hum. Also look for hum bars on the video.

Okay, gotta find an RCA adapter. Radio Shark, here I come.

You don't really need one, you can hold the tip and ring of the headphone
plug against the tip and shield of a male RCA with your hands for a couple
seconds. But it's handy to have one.

They have nine video receivers, four of which are hooked to the Onkyo
receiver.

How? Do they have RF coming out or baseband video? If it's baseband
video, is it going into any kind of distribution amp?

If you hear it on headphones and see noise on the video, it's time to start
tearing the satellite system and the video distribution system coming out of
it apart.

That'll be somebody else's job. g

Probably not. Video guys seem not to know anything about audio and most
of them seem clueless about grounding too...
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[hank alrich]

Scott Dorsey wrote:

hank alrich wrote:
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?

The _input_ caps before the transformer are more likely to be the problem,
unless this is a hot chassis unit with a switching supply in which case
all bets are off.

I am ASSUMING that you are seeing this voltage with nothing plugged into
the receiver, because the cable TV and satellite systems are prime sources
for induced noise.

Thanks. Will double-check that next round.

2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

This is normal. SOME of it may be on the feed itself. Use a pair of
headphones and connect it to one of the RCA audio feeds and see if you
hear the hum. Also look for hum bars on the video.

Okay, gotta find an RCA adapter. Radio Shark, here I come.

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".

You don't need the MIO or anything but a pair of headphones with an RCA
adaptor. Headphones are the most powerful debugging tool you have available
to you because they allow you to listen to a line-level signal without any
possibility of introducing additional ground loops.

I cheerfully and gratefully solicit advice and commentary. At this point
they cannot feed audio from the video receivers into the house speaker
system driven by the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm figuring they
need to replace the Onkyo, for starters, but I'm not convinced that's
going to take care of the video-related audio noise problem.

If you don't hear it on headphones and there are no hum bars on the video,
use audio isolation transformers between the receiver and the video system.

They have nine video receivers, four of which are hooked to the Onkyo
receiver.

If you hear it on headphones and see noise on the video, it's time to start
tearing the satellite system and the video distribution system coming out of
it apart.

That'll be somebody else's job. g


--
ha
Iraq is Arabic for Vietnam

[hank alrich]

rsmith wrote:

Hank,

Here are some additional items you might find useful:

1) Ebtech Hum-Eliminator - cheap transformer just to break signal DC
paths for diagnostics
2) portable, battery operated player like an iPod to test inputs
without ground issues
3) headphones like Scott says to listen to feeds

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com

Thanks very much to all for such a complete list of crap to go back and
try. Some of this I've already covered but won't bother to reply to all
right now. I'll be back there tomorrow with some additional tools and a
truckload of additional information, thanks to folks here.

--
ha
Iraq is Arabic for Vietnam

[Scott Dorsey]

hank alrich wrote:
They have nine video receivers, four of which are hooked to the Onkyo
receiver.

How? Do they have RF coming out or baseband video? If it's baseband
video, is it going into any kind of distribution amp?

Okay, you understand I don't know squat about video. They have feeds
coming from dishes into the closet, into some kind of box(es) which then
feed the video receivers, which then feed the big Philps screens, all
that via coax. The video receivers have RCA outputs for audio, and those
are connected to the Onkyo receiver.

If it's on an F connector that screws in, it's RF, and goes into the
antenna input of a TV set. If it's an RCA or BNC connector, it carries
actualy baseband video and goes into a video input.

It's easy to break ground loops on RF links, hard to break them on
baseband video links.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[hank alrich]

Scott Dorsey wrote:

hank alrich wrote:

This is normal. SOME of it may be on the feed itself. Use a pair of
headphones and connect it to one of the RCA audio feeds and see if you
hear the hum. Also look for hum bars on the video.

Okay, gotta find an RCA adapter. Radio Shark, here I come.

You don't really need one, you can hold the tip and ring of the headphone
plug against the tip and shield of a male RCA with your hands for a couple
seconds. But it's handy to have one.

In this closet I'll take the adapter over trying to hold things in
place!

They have nine video receivers, four of which are hooked to the Onkyo
receiver.

How? Do they have RF coming out or baseband video? If it's baseband
video, is it going into any kind of distribution amp?

Okay, you understand I don't know squat about video. They have feeds
coming from dishes into the closet, into some kind of box(es) which then
feed the video receivers, which then feed the big Philps screens, all
that via coax. The video receivers have RCA outputs for audio, and those
are connected to the Onkyo receiver.

If you hear it on headphones and see noise on the video, it's time to
start tearing the satellite system and the video distribution system
coming out of it apart.

That'll be somebody else's job. g

Probably not. Video guys seem not to know anything about audio and most
of them seem clueless about grounding too...

Best Buy guys did this install, and juding from what I've seen of their
wiring work in the upstairs piano bar of this same place, I guess I'll
face getting some videoesque education on this one.

Thanks, Scott. Obviously, I'll be back here for more coaching.

Tomorrow I'll take the laptop as a source for groundloopless audio feed,
the headphones and adapter, the Fluke and these great replies, and go
down the list of moves from all the posts. Data gathering time.

--
ha
Iraq is Arabic for Vietnam

[paul]

hum job in a sports bar? that happened to me once...


"hank alrich" wrote in message
...
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?


2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".


I cheerfully and gratefully solicit advice and commentary. At this point
they cannot feed audio from the video receivers into the house speaker
system driven by the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm figuring they
need to replace the Onkyo, for starters, but I'm not convinced that's
going to take care of the video-related audio noise problem.

--
ha
Iraq is Arabic for Vietnam

[hank alrich]

paul wrote:

hum job in a sports bar? that happened to me once...

Yeah, buddy, but I don't need consultants to help me with that one.

--
ha
Iraq is Arabic for Vietnam

[JSVice]

I have nothing constructive to say, except that "bar hum job" reminds me of
something Ebenezer Scrooge might say.

--
Thanks,
John
"hank alrich" wrote in message
...
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?


2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".


I cheerfully and gratefully solicit advice and commentary. At this point
they cannot feed audio from the video receivers into the house speaker
system driven by the Onkyo, at all, and can stand to play CD's only with
the bass level control on the Onkyo turned way down. I'm figuring they
need to replace the Onkyo, for starters, but I'm not convinced that's
going to take care of the video-related audio noise problem.

--
ha
Iraq is Arabic for Vietnam

[Richard Crowley]

"Scott Dorsey" wrote ...
If it's on an F connector that screws in, it's RF, and goes into the
antenna input of a TV set. If it's an RCA or BNC connector, it
carries
actualy baseband video and goes into a video input.

It's easy to break ground loops on RF links, hard to break them on
baseband video links.

Perhaps not so much "hard" as "expensive". There are several
vendors of iso transformers for video. I have used a couple
models of them and they worked great in difficult situations.

[Les Cargill]

JSVice wrote:

I have nothing constructive to say, except that "bar hum job" reminds me of
something Ebenezer Scrooge might say.


Brings to mind an interesting variation on the story, tho... nudge
nudge, say no more...

--
Les Cargill

[hank alrich]

Richard Crowley wrote:

"hank alrich" wrote ...
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads
I've determined that the ground is good and that the AC to the closet
with the CD changer, Onkyo receiver and a stack of DishNet video
receivers is good, too.

There are two hum-related problems he

1. A certain amount of hum seems related directly to the Onkyo receiver
in that about 3.5 volts is showing between the chassis of the CD player
and the receiver (probing at the ground collars of their respective RCA
connectors) when the system is first started cold after being turned-off
overnight. As it warms up that rises, to as much as 12 volts. When the
CD player AC power was sourced from an outlet on the back of the
receiver I measured 10.5 volts at cold start, and lord only knows what
it must have been after warming up. When I hooked the CD changer's AC
cable to the same power strip feeding the rest of the gear in the closet
the voltage dropped to 3.5 cold.

Do any of the units have 3-prong power plugs/cables?

The seven video receivers are 3-prongers.

Or 2-prong?

The Onkyo receiver and the Sony CD changer are 2-prong.

Exactly where/how are these plugged into the source of power?

There's a quad box outlet on the wall behind the units.

Are they all running from a power strip? Or more than one?

There are two power strips, connected to adjacent outlets in the quad
box.

Is everything on the same branch circuit (breaker)?

Everything in the closet is, but I wonder about the TV's to which the
receivers feed signal.

How new/reliable is the building wiring?

Good question; most of it's definitely not new, has obviously been
expanded in various stages.

How good are the green-wire grounds?

I don't know. If I measure between contacts at the quad box or power
strips I get:

120.5 V hot to neutral
0.5 V neutral to ground
6.4 V hot to ground

Should I run a long lead from the ground rod to the closet and read Ohms
for that link to see if the building wiring actually connects the greens
properly to the stake?

What are the startup and warm-up chassis voltages relative to
green-wire ground? Else you are only measuring the differential
between reciever and CD player, etc. which is the equivalent of
one equation and two unknowns. We don't know which unit is
behaving badly (or perhaps both).

Right now I'm in the closet. I've had the gear powerd-up for about three
hours, so it's well warmed-up. I measure 0.35 V Onkyo chassis to green
wire ground (via one of the power strips), with nothing connected to the
Onkyo inputs, and the same for the Sony Cd player to ground. I measure
12.8 V chassis-to-chassis (Onkyo-to-Sony).

But some of these measurements seem not always repeatable. Sometimes I
get that 12.8 V, next time I get 10 V, then 12.8 again, and so forth,
and that seems to apply to all I read at the Onkyo and Sony, but not for
the measurements made at the quadbox or power strips, which remain far
more stable.

Does the system hum with an isolated source (an MP3 player, etc.)?

Lots of hum when Onkyo fed by TiBook running on power supply.
No hum when running on battery with nothing else connected, but add the
CD player and get modest hum, add video receiver, even one leg of one
receiver, and loads of hum.

The Onkyo doesn't hum when nothing is connected to it, and it doesn't
hum when FM is selected, playing radio, whether or not the CD player
and/or video receivers are connected to the it.

What is the chassis voltage of the receiver with nothing attached?
(relative to green-wire ground)

See above.

Does it change with the speaker lines connected?

No.

Is this a sign that the power supply filter caps in the receiver are
leaking, and leaking more as they heat?

Filter caps in the power supply should have NO effect on the
chassis voltage. Regardless of how bad they are or what temp.
If they do, something is seriously wacko (perhaps dangerous?)
Certainly bad filter caps will contribute to hum in the system,
but you should NOT see any of it at the chassis ground point.

2. There is a ridiculous amount of hum coming via the audio feeds from
the DishNet video recievers, fed to the Onkyo receivers audio inputs.
Yet there is no comparably appreciable voltage showing between those
chassis; measuring again RCA's-to-RCA's I see single-digit millivolts.

Normally one would see zero volts between the chassis of the
various components. Audible hum could have other sources than
differential ground potentials.

Does the receiver hum with no inputs connected?
What is the receiver chassis voltage relative to green-wire gnd?

Classic case of disconnect everything and then restore it one
connection at a time and see the effect of each individual
connection.

Yep, been doing that today.

While everything is disconnected, measure each chassis
voltage against a common reference (mains green-wire gnd)

I plan to go back with the MIO and feed audio from the video receivers
to SpectraFoo to see if noise associated with those audio feeds is
actually being delivered along with the intended audio, i.e., if that
hum is not simply inter-component ground related, but part of the
"signal".

What do the isolated outputs of the satellite receivers sound
like by themselves (on headphones, etc.)?

They sound okay feeding phones directly.

What is the chassis voltage of the sattelite recievers (each
of them isolated) relative to green-wire ground?

0.9 to 1 V.


There is a standardized way of testing the safety of the exposed
metal parts of equipment. I will look up the details when I get
home. IIRC, it is a resistor and a capacitor and a multimeter.
I didn't find anything online. Likely using the wrong search term.

Is the RF feed from the satellite dish(es) grounded at any
other point?

Will be checking that next round. I have just discovered a potential
problem, but I haven't gotten a clear answer from the owners. There are
two separate electrical services (2 separate meters). There is a
possiblity that the downstairs sports bar is fed from one of these and
the upstairs piano bar from the other. If that's the case it could be
trouble since two of the video receivers in the closet feed screens
upstairs. I assume the video feeds (RF I think, based on Scott's
description of the connector type) are shielded, connecting receiver
chassis to video screen chassis, and that might give us the ground loop.

I can't proceed further today, as the joint is open for St. Paddy's Day
and I can't go 'round flipping breakers to see what's what. I've been
poking around in this long enough for an average Saturday anyway. "Get
me out of this closet!" g There's going to be a jam here tonight and
it's time to deFluke, go get food, and then break out the mandolin,
banjo and guitar.

Frequently there is a "grounding block" before
the coax enters the building. This is supposed to be connected
with a stout wire to a physical ground (water pipe, etc.) as a
primary protection against lightning/static entering via the
sattelite dish cable. If the grounding blocks are connected
to some kind of ground that is different than the ground used
by the electrical power system in the building, that could be
a source of significant ground potentials right there. This is
frequently a problem with cable systems, also where the
cable system's notion of ground isn't necessarily the same
as the power mains.

Okay, thanks for that, as well as for the rest of this, Richard. I'll
chase that stuff next round if the possibility of two juice feeds for
the down and up stairs rooms turns out to be a false lead.

--
ha
Iraq is Arabic for Vietnam

[Richard Crowley]

"hank alrich" wrote ...
Richard Crowley wrote:

How good are the green-wire grounds?

I don't know. If I measure between contacts at the quad box or power
strips I get:

120.5 V hot to neutral
0.5 V neutral to ground
6.4 V hot to ground

If "6.4 V" is not a typo, it seems like a BIG PROBLEM.

The Neutral (white) and Ground (green) are supposed to
be tied together somewhere back around the breaker box.
Even if this is fed from a 3-phase power drop from the
utility, there should be virtually zero V between neutral
and ground, and the voltage between hot and neutral
should be the same as between hot and ground.

This may be an indication of serious/dangerous problems
with the power wiring. I'd seriously consider telling them
to get a licensed electrician to correct/confirm the wiring
before proceeding with any signal wiring debugging, etc.

If it were a private residence we could discuss debugging
processes for fixing (or at least identifying) this problem.
But since this is a public building, it would be inappropriate
to suggest anything but legal work by a licensed electrician.

Should I run a long lead from the ground rod to the closet and read
Ohms
for that link to see if the building wiring actually connects the
greens
properly to the stake?

I would defer to a licensed electrician. You may have
identified a dangerous mains wiring problem.

Does the system hum with an isolated source (an MP3 player, etc.)?

Lots of hum when Onkyo fed by TiBook running on power supply.

But that happens to most of us. The power supplies on
laptop computers are notoriously reliable sources of noise.

No hum when running on battery with nothing else connected,

THAT is the test of whether the amplifier and speakers by
themselves have a problem. You seem to have confirmed
that the amp/speaker combo are "clean".

but add the CD player and get modest hum,

Can you plug the CD player into the power strip adjacent
to the amplifier? Is the plug on the CD player reversible?

add video receiver, even one leg of one receiver,
and loads of hum.

I suspected those satellite receivers from the start (:-)

The Onkyo doesn't hum when nothing is connected to it, and it doesn't
hum when FM is selected, playing radio, whether or not the CD player
and/or video receivers are connected to the it.

In that case, you might get away with those cheap/simple
stereo line-level isolation transformers they sell at Rat Shack.

What do the isolated outputs of the satellite receivers sound
like by themselves (on headphones, etc.)?

They sound okay feeding phones directly.

So it is only when connected to the amplifier that we start
seeing the ground loops, etc. It may be easier to use the
iso transformer(s) than to try to "fix" the grounding problem
with the satellite receivers. Especially since the grounding
of the RF line is likely required by local code.

Will be checking that next round. I have just discovered a potential
problem, but I haven't gotten a clear answer from the owners. There
are
two separate electrical services (2 separate meters). There is a
possiblity that the downstairs sports bar is fed from one of these
and
the upstairs piano bar from the other. If that's the case it could be
trouble since two of the video receivers in the closet feed screens
upstairs. I assume the video feeds (RF I think, based on Scott's
description of the connector type) are shielded, connecting receiver
chassis to video screen chassis, and that might give us the ground
loop.

Yikes. it would be interesting to know what is the voltage
differential between the green-wire "ground" on each system.
Or perhaps we don't WANT to know. :-/

If the video is being distributed from the receivers to the TV
screens via RF (threaded "F-connectors" vs. RCA or BNC)
then it may be easier to use one of those RF iso transformers
like they sell for home theater people with cable system ground
loop problems.

[[email protected]]

On Mar 18, 11:06 am, (hank alrich) wrote:
Richard Crowley wrote:
"hank alrich" wrote ...
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads

How good are the green-wire grounds?

I don't know. If I measure between contacts at the quad box or power
strips I get:

120.5 V hot to neutral
0.5 V neutral to ground
6.4 V hot to ground

WHOAAA!! I hope that 6.4V hot to ground is a typo!! If not you have a
serious and potentially dangerous problem. It should be very close to
the same voltage as the hot to neutral.


Will be checking that next round. I have just discovered a potential
problem, but I haven't gotten a clear answer from the owners. There are
two separate electrical services (2 separate meters). There is a
possiblity that the downstairs sports bar is fed from one of these and
the upstairs piano bar from the other. If that's the case it could be
trouble since two of the video receivers in the closet feed screens
upstairs. I assume the video feeds (RF I think, based on Scott's
description of the connector type) are shielded, connecting receiver
chassis to video screen chassis, and that might give us the ground loop.

If you are dealing with two separate circuits, you may be better off
just using the appropriate transformer that minimizes the hum, either
an RF isolator or an audio transformer such as an Ebtech or possibly
both.

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com

[hank alrich]

Les Cargill wrote:

JSVice wrote:

I have nothing constructive to say, except that "bar hum job" reminds me of
something Ebenezer Scrooge might say.


Brings to mind an interesting variation on the story, tho... nudge
nudge, say no more...

Are y'all talkin' about Ebeneazier Screwge?

--
ha
Iraq is Arabic for Vietnam

[hank alrich]

Richard Crowley wrote:

"hank alrich" wrote ...
Richard Crowley wrote:

How good are the green-wire grounds?

I don't know. If I measure between contacts at the quad box or power
strips I get:

120.5 V hot to neutral
0.5 V neutral to ground
6.4 V hot to ground

If "6.4 V" is not a typo, it seems like a BIG PROBLEM.

It's not a typo, and I have repeated the measurement several times,
getting the same answer within a few millivolts every time.

The Neutral (white) and Ground (green) are supposed to
be tied together somewhere back around the breaker box.
Even if this is fed from a 3-phase power drop from the
utility, there should be virtually zero V between neutral
and ground, and the voltage between hot and neutral
should be the same as between hot and ground.

I will go look into the service panels to see what's up in there.

This may be an indication of serious/dangerous problems
with the power wiring. I'd seriously consider telling them
to get a licensed electrician to correct/confirm the wiring
before proceeding with any signal wiring debugging, etc.

If it were a private residence we could discuss debugging
processes for fixing (or at least identifying) this problem.
But since this is a public building, it would be inappropriate
to suggest anything but legal work by a licensed electrician.

Since their licensed electrician has told them everything is cool, I
guess maybe I should try to find them a different electrician. At
minimum I can look more deeply into this, at the primary service panels,
to see if I observe something obvious enough to point it out to an
inobservant electrician.

Should I run a long lead from the ground rod to the closet and read
Ohms
for that link to see if the building wiring actually connects the
greens
properly to the stake?

I would defer to a licensed electrician. You may have
identified a dangerous mains wiring problem.

See above... g

Does the system hum with an isolated source (an MP3 player, etc.)?

Lots of hum when Onkyo fed by TiBook running on power supply.

But that happens to most of us. The power supplies on
laptop computers are notoriously reliable sources of noise.

No hum when running on battery with nothing else connected,

THAT is the test of whether the amplifier and speakers by
themselves have a problem. You seem to have confirmed
that the amp/speaker combo are "clean".

Okay.

but add the CD player and get modest hum,

Can you plug the CD player into the power strip adjacent
to the amplifier?

Have done so, and left it that way. Same result.

Is the plug on the CD player reversible?

Both the Onkyo and the Sony have keyed plugs, so without taking a file
to them, not reversible.

add video receiver, even one leg of one receiver,
and loads of hum.

I suspected those satellite receivers from the start (:-)

That's what people get for watching that stuff! g

The Onkyo doesn't hum when nothing is connected to it, and it doesn't
hum when FM is selected, playing radio, whether or not the CD player
and/or video receivers are connected to the it.

In that case, you might get away with those cheap/simple
stereo line-level isolation transformers they sell at Rat Shack.

What do the isolated outputs of the satellite receivers sound
like by themselves (on headphones, etc.)?

They sound okay feeding phones directly.

So it is only when connected to the amplifier that we start
seeing the ground loops, etc. It may be easier to use the
iso transformer(s) than to try to "fix" the grounding problem
with the satellite receivers. Especially since the grounding
of the RF line is likely required by local code.

Will be checking that next round. I have just discovered a potential
problem, but I haven't gotten a clear answer from the owners. There
are
two separate electrical services (2 separate meters). There is a
possiblity that the downstairs sports bar is fed from one of these
and
the upstairs piano bar from the other. If that's the case it could be
trouble since two of the video receivers in the closet feed screens
upstairs. I assume the video feeds (RF I think, based on Scott's
description of the connector type) are shielded, connecting receiver
chassis to video screen chassis, and that might give us the ground
loop.

Yikes. it would be interesting to know what is the voltage
differential between the green-wire "ground" on each system.
Or perhaps we don't WANT to know. :-/

I think I need to know, because something tells me every time they need
something sound-wise, they're going to call me. That's not necessarily a
bad thing, as long as I don't get killed in there.

If the video is being distributed from the receivers to the TV
screens via RF (threaded "F-connectors" vs. RCA or BNC)
then it may be easier to use one of those RF iso transformers
like they sell for home theater people with cable system ground
loop problems.

Yes, to the best of my inspection, they are not RCA or BNC connectors,
but rather heavier duty, screw-on connectors with hex-nut style collars
for more-than-finger-tightening ability.

Richard, thanks for your help. Maybe we can have you over for tofu chili
someday.

--
ha
Iraq is Arabic for Vietnam

[hank alrich]

wrote:

hank alrich wrote:
Richard Crowley wrote:
"hank alrich" wrote ...
I'm helping folks who have a sports bar get some of their audio action
working better. Following info from RAP in other ground problem threads

How good are the green-wire grounds?

I don't know. If I measure between contacts at the quad box or power
strips I get:

120.5 V hot to neutral
0.5 V neutral to ground
6.4 V hot to ground

WHOAAA!! I hope that 6.4V hot to ground is a typo!! If not you have a
serious and potentially dangerous problem. It should be very close to
the same voltage as the hot to neutral.

That's what I thought, and no, it's not a typo. Oh, boy...

Will be checking that next round. I have just discovered a potential
problem, but I haven't gotten a clear answer from the owners. There are
two separate electrical services (2 separate meters). There is a
possiblity that the downstairs sports bar is fed from one of these and
the upstairs piano bar from the other. If that's the case it could be
trouble since two of the video receivers in the closet feed screens
upstairs. I assume the video feeds (RF I think, based on Scott's
description of the connector type) are shielded, connecting receiver
chassis to video screen chassis, and that might give us the ground loop.

If you are dealing with two separate circuits, you may be better off
just using the appropriate transformer that minimizes the hum, either
an RF isolator or an audio transformer such as an Ebtech or possibly
both.

Thanks, Bob. I'll dig a little deeper into this, and be back with
another scary report.

--
ha
Iraq is Arabic for Vietnam

[Les Cargill]

hank alrich wrote:

Les Cargill wrote:


JSVice wrote:


I have nothing constructive to say, except that "bar hum job" reminds me of
something Ebenezer Scrooge might say.


Brings to mind an interesting variation on the story, tho... nudge
nudge, say no more...


Are y'all talkin' about Ebeneazier Screwge?


AB. SO. LUTE. LY.

--
Les Cargill

Hank , every one else is well along with get ideas for your problem
I am wondering if there is a optical link you could make and simply avoid
the whole issue
then if the video recievers cause a problem , dump it back on the videots
george

[Arny Krueger]

"Richard Crowley" wrote in message

"hank alrich" wrote ...
Richard Crowley wrote:

How good are the green-wire grounds?

I don't know. If I measure between contacts at the quad
box or power strips I get:

120.5 V hot to neutral
0.5 V neutral to ground
6.4 V hot to ground

If "6.4 V" is not a typo, it seems like a BIG PROBLEM.

It suggests to me that ground is floating.

The Neutral (white) and Ground (green) are supposed to
be tied together somewhere back around the breaker box.

Big time!

Even if this is fed from a 3-phase power drop from the
utility, there should be virtually zero V between neutral
and ground, and the voltage between hot and neutral
should be the same as between hot and ground.

A fraction of a volt diff wouldn't bother me, but they should be very close.

This may be an indication of serious/dangerous problems
with the power wiring. I'd seriously consider telling
them to get a licensed electrician to correct/confirm the
wiring before proceeding with any signal wiring
debugging, etc.

Agreed.

If it were a private residence we could discuss debugging
processes for fixing (or at least identifying) this
problem. But since this is a public building, it would be
inappropriate to suggest anything but legal work by a
licensed electrician.

Agreed. But, back in the real world...

Should I run a long lead from the ground rod to the
closet and read Ohms
for that link to see if the building wiring actually
connects the greens
properly to the stake?

I'd put a voltmeter between the two, first.

I would defer to a licensed electrician. You may have
identified a dangerous mains wiring problem.

That, too.

Does the system hum with an isolated source (an MP3
player, etc.)?

Lots of hum when Onkyo fed by TiBook running on power
supply.

But that happens to most of us. The power supplies on
laptop computers are notoriously reliable sources of
noise.

So is just about everything else, these days.

BTW, know what the power supply on a Microtrack is? Switchmode.

[Richard Crowley]

"Arny Krueger" wrote ...
BTW, know what the power supply on a Microtrack is?
Switchmode.

How could it possibly be anything else?

[Arny Krueger]

"Richard Crowley" wrote in message


"Arny Krueger" wrote ...

BTW, know what the power supply on a Microtrack is?
Switchmode.

How could it possibly be anything else?

It could be analog. In fact I could whip up an analog one in less than an
hour. I'd just solder a 5 volt 1 amp DC supply to the power lines on a USB
cable.

Fact of the matter, the switchmode PS on the Microtrak seems to be pretty
benign.

I'll keep flogging it and see what happens. This is a busy time of the year
for me. I recorded almost 100 groups last week. The MT is my safety
recorder, the prime recorder being a nice little Tascam CDR.

[Arny Krueger]

"hank alrich" wrote in message


I don't think I'm going to get to dump anythinng back on
anybody. The licensed electrician says everything's fine,

Given the evidence you've provided, I find that hard to believe.

Do you have one of those electrician's $6 plug-in line and grounding
checkers? Lowes and HD have them, as do many hardware and all electrical
supply houses. I wouldn't be surprised if Walgreen's had them but I've never
seen one there, ;-)

Based on your comments, it should fail some if not all of the outlets you're
working with. If it doesn't then you need to go back and check your
measurements. If it does fail some outlets, then you would be speaking a
language the electrician should be able to understand.

[GregS]

In article , "Richard Crowley" wrote:
"Arny Krueger" wrote ...
BTW, know what the power supply on a Microtrack is?
Switchmode.

How could it possibly be anything else?

Laptop supplies usually have ground connected usually causing ground loops.
Switchmode supplies are typically better at isolating 60Hz feedthrough..

greg

[hank alrich]

George G wrote:

Hank , every one else is well along with get ideas for your problem
I am wondering if there is a optical link you could make and simply avoid
the whole issue
then if the video recievers cause a problem , dump it back on the videots
george

Tomorrow I'll see if disconnecting the lines feeding video to the piano
bar breaks the ground loop, and if that makes any difference on the
unfortunate voltage potential between hot and ground. I discovered the
possibility that the two rooms are receiving electricity from separate
services.

I don't think I'm going to get to dump anythinng back on anybody. The
licensed electrician says everything's fine, the vidiots are from a Best
Buy in Reno (100+ miles one-way), etc. I think I'm in for a learning
experience.

--
ha
Iraq is Arabic for Vietnam

[Arny Krueger]

"hank alrich" wrote in message

Arny Krueger wrote:

"hank alrich" wrote

I don't think I'm going to get to dump anythinng back on
anybody. The licensed electrician says everything's
fine,

Given the evidence you've provided, I find that hard to
believe.

You are not alone in that disbelief. But having lived
here for over twenty years I am resigned to a reality
wherein one must both know something about any service
for which one wishes to procure help, and then do some
serious local research to find out who can really help
properly.

Do you have one of those electrician's $6 plug-in line
and grounding checkers? Lowes and HD have them, as do
many hardware and all electrical supply houses. I
wouldn't be surprised if Walgreen's had them but I've
never seen one there, ;-)

Yep, and it doesn'[t say much except that all the lines
are connected.

Former measurements suggested that not all the lines are connected. Neutral
and safety ground didn't seem to be right.

The proper lights light-up, but those
don't give voltage readings.

They give rough voltage info. They don't light up at low voltages, and they
get brighter at higher voltages.

Based on your comments, it should fail some if not all
of the outlets you're working with. If it doesn't then
you need to go back and check your measurements. If it
does fail some outlets, then you would be speaking a
language the electrician should be able to understand.

I plan to make measurements at many more outlets now, but
truly, I have repeated the measurements stated enough
times to eliminate my own disbelief of their validity.

Any possibility that a GFCI somewhere tripped along the way?

[hank alrich]

Arny Krueger wrote:

"hank alrich" wrote

I don't think I'm going to get to dump anythinng back on
anybody. The licensed electrician says everything's fine,

Given the evidence you've provided, I find that hard to believe.

You are not alone in that disbelief. But having lived here for over
twenty years I am resigned to a reality wherein one must both know
something about any service for which one wishes to procure help, and
then do some serious local research to find out who can really help
properly.

Do you have one of those electrician's $6 plug-in line and grounding
checkers? Lowes and HD have them, as do many hardware and all electrical
supply houses. I wouldn't be surprised if Walgreen's had them but I've never
seen one there, ;-)

Yep, and it doesn'[t say much except that all the lines are connected.
The proper lights light-up, but those don't give voltage readings.

Based on your comments, it should fail some if not all of the outlets you're
working with. If it doesn't then you need to go back and check your
measurements. If it does fail some outlets, then you would be speaking a
language the electrician should be able to understand.

I plan to make measurements at many more outlets now, but truly, I have
repeated the measurements stated enough times to eliminate my own
disbelief of their validity.

--
ha
Iraq is Arabic for Vietnam

[[email protected]]

On Mar 19, 8:49 am, (hank alrich) wrote:
Arny Krueger wrote:

Do you have one of those electrician's $6 plug-in line and grounding
checkers? Lowes and HD have them, as do many hardware and all electrical
supply houses. I wouldn't be surprised if Walgreen's had them but I've never
seen one there, ;-)

Yep, and it doesn'[t say much except that all the lines are connected.
The proper lights light-up, but those don't give voltage readings.

Hank, something is seriously amiss.Those little outlet checkers use
neon lamps which require greater than 60~90V to light. If the outlet
checker's Ground lamp indicates OK but your measurements say Hot to
Ground is 6.4V then there is a conflict here. Both can't be true. One
trick to watch out for: some schmucks will run a wire from the neutral
to the ground on the back side of outlet, so from the outside it
checks ok. As long as the neutral doesn't fail anywhere in the
circuit, it appears to work but is very unsafe.

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com

[Scott Dorsey]

hank alrich wrote:
But some of these measurements seem not always repeatable. Sometimes I
get that 12.8 V, next time I get 10 V, then 12.8 again, and so forth,
and that seems to apply to all I read at the Onkyo and Sony, but not for
the measurements made at the quadbox or power strips, which remain far
more stable.

This is because there is RF trash on those grounds, not just 60 Hz stuff,
and the meter is not reading it consistently.

What do the isolated outputs of the satellite receivers sound
like by themselves (on headphones, etc.)?

They sound okay feeding phones directly.

Bingo. And the Onkyo is fine by itself too. But when you plug them in
together, you get hum.

Stick an isolation transformer between one receiver and the Onkyo.
It won't hum, I bet.

This, incidentally, is why balanced line is used in professional installs.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

In article ,
GregS wrote:
In article , "Richard Crowley" wrote:
"Arny Krueger" wrote ...
BTW, know what the power supply on a Microtrack is?
Switchmode.

How could it possibly be anything else?

Laptop supplies usually have ground connected usually causing ground loops.
Switchmode supplies are typically better at isolating 60Hz feedthrough..

Laptop supplies are usually the worst possible switchmode devices, and spew
huge amounts of high frequency junk on both their inputs and outputs. And
plenty of RFI too!
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."