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Ground control to Major Tom

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Anonymous
June 22, 2005 4:26:03 AM

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

Have recently replaced deck and tape deck on my hi-fi. Have an
intermittent problem with tape deck where I get a buzzing staticy sort
of noise out of the speakers - doesn't seem to transfer to tape if I'm
recording though. Goes away if I power off and on again. No obvious
correlation with flushing of toilet, fridge deforst cycle starting up,
atmospherics or phase of moon. I had a similar sort of problem a while
back with an old amp, and read a lot about earth loops without ever
feeling I really got to grips with them. The problem /could/ be a
faulty unit, I suppose, but I'm pretty certain its an earth loop
thing.

My question is this: some hi-fi separates are double-insulated and
some not. If a hi-fi system consists of a mixture of both, and they
are plugged into the mains via an N-way extension block, could this
cause earth loop problems? I should say I don't actually know at the
moment whether my system is a "hybrid" or not, and its 01:30 and I'm
not about to start pulling it apart to find out just at the moment ...
if the answer is in the affirmative, is there any solution other than
to change one or more separates so as to get a consistent earthing
convention?
Anonymous
June 22, 2005 4:26:04 AM

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

Sounds more like a loose connection...
Anonymous
June 22, 2005 4:26:04 AM

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

In article <1119399968.4338a112d99774918d910adf1719e6f9@teranews>,
andy@sparge.globalnet.co.uk (Andy Spragg) wrote:

> Have recently replaced deck and tape deck on my hi-fi. Have an
> intermittent problem with tape deck where I get a buzzing staticy sort
> of noise out of the speakers - doesn't seem to transfer to tape if I'm
> recording though. Goes away if I power off and on again. No obvious
> correlation with flushing of toilet, fridge deforst cycle starting up,
> atmospherics or phase of moon. I had a similar sort of problem a while
> back with an old amp, and read a lot about earth loops without ever
> feeling I really got to grips with them. The problem /could/ be a
> faulty unit, I suppose, but I'm pretty certain its an earth loop
> thing.
>
> My question is this: some hi-fi separates are double-insulated and
> some not. If a hi-fi system consists of a mixture of both, and they
> are plugged into the mains via an N-way extension block, could this
> cause earth loop problems? I should say I don't actually know at the
> moment whether my system is a "hybrid" or not, and its 01:30 and I'm
> not about to start pulling it apart to find out just at the moment ...
> if the answer is in the affirmative, is there any solution other than
> to change one or more separates so as to get a consistent earthing
> convention?

The power switch could be crusty. There's a quick'n'dirty way to fix it
- Turn the unit off, connect the AC plug to a 12V battery, turn it on,
wait a few seconds, then disconnect the BATTERY. This will burn through
any crud on the switch contacts. Don't turn the switch off while DC
current is flowing or it will be incinerated.
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Anonymous
June 22, 2005 10:07:59 AM

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

> The power switch could be crusty. There's a quick'n'dirty way to fix it
> - Turn the unit off, connect the AC plug to a 12V battery, turn it on,
> wait a few seconds, then disconnect the BATTERY. This will burn through
> any crud on the switch contacts. Don't turn the switch off while DC
> current is flowing or it will be incinerated.

I have never heard of this. What is the theory of operation? Does it work
better than a high quality contact cleaner like Caig Labs?
Anonymous
June 22, 2005 10:08:00 AM

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

In article <3f7ue.1125$fw1.827@trnddc02>,
"Karl Uppiano" <karl.uppiano@verizon.net> wrote:

> > The power switch could be crusty. There's a quick'n'dirty way to fix it
> > - Turn the unit off, connect the AC plug to a 12V battery, turn it on,
> > wait a few seconds, then disconnect the BATTERY. This will burn through
> > any crud on the switch contacts. Don't turn the switch off while DC
> > current is flowing or it will be incinerated.
>
> I have never heard of this. What is the theory of operation? Does it work
> better than a high quality contact cleaner like Caig Labs?

No, it's a hack.

The AC power transformer acts as an inductor - a constant current source
for DC. If the switch breaks momentarily contact due to dirt, the
transformer will develop almost any voltage needed to maintain the
current. The dirt gets blasted. That's also why you must break the
current at the battery first.
Anonymous
June 22, 2005 3:07:26 PM

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

Karl Uppiano wrote:
>> The power switch could be crusty. There's a quick'n'dirty way to
>> fix it - Turn the unit off, connect the AC plug to a 12V battery,
>> turn it on, wait a few seconds, then disconnect the BATTERY. This
>> will burn through any crud on the switch contacts. Don't turn the
>> switch off while DC current is flowing or it will be incinerated.
>
> I have never heard of this. What is the theory of operation? Does it
> work better than a high quality contact cleaner like Caig Labs?

I haven't had much luck cleaning power switches anyway, with Caig or any
other cleaner.

Some power switches are so bad nothing will do except replacement or
bypassing, but Kevin's method might be worth a try... I plan to experiment
with it.

Mark Z.
Anonymous
June 22, 2005 4:50:57 PM

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

Andy Spragg wrote:
> Have recently replaced deck and tape deck on my hi-fi. Have an
> intermittent problem with tape deck where I get a buzzing staticy sort
> of noise out of the speakers - doesn't seem to transfer to tape if I'm
> recording though. Goes away if I power off and on again. No obvious
> correlation with flushing of toilet, fridge deforst cycle starting up,
> atmospherics or phase of moon. I had a similar sort of problem a while
> back with an old amp, and read a lot about earth loops without ever
> feeling I really got to grips with them. The problem /could/ be a
> faulty unit, I suppose, but I'm pretty certain its an earth loop
> thing.
>
> My question is this: some hi-fi separates are double-insulated and
> some not. If a hi-fi system consists of a mixture of both, and they
> are plugged into the mains via an N-way extension block, could this
> cause earth loop problems? I should say I don't actually know at the
> moment whether my system is a "hybrid" or not, and its 01:30 and I'm
> not about to start pulling it apart to find out just at the moment ...
> if the answer is in the affirmative, is there any solution other than
> to change one or more separates so as to get a consistent earthing
> convention?

If it's an intermittant, but fairly regular 'buzz, buzz' noise, it could be
your cel phone checking in with the network. Try placing the phone near the
stereo system and calling it from a landline to confirm.

I get this one all the time on various pieces of consumer audio gear. I
even use it to advantage in my car. I placed the 'button holder' receptacle
right next to the radio. When the phone rings, even if I've inadvertantly
left it on silent, it buzzes through the radio.

jak
Anonymous
June 23, 2005 3:14:54 AM

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

On Wed, 22 Jun 2005 12:50:57 -0500, "jakdedert"
<jdedert@bellsouth.net> wrote:

>If it's an intermittant, but fairly regular 'buzz, buzz' noise, it could be
>your cel phone checking in with the network. Try placing the phone near the
>stereo system and calling it from a landline to confirm.
>
>I get this one all the time on various pieces of consumer audio gear. I
>even use it to advantage in my car. I placed the 'button holder' receptacle
>right next to the radio. When the phone rings, even if I've inadvertantly
>left it on silent, it buzzes through the radio.

Hi Jak,

It's an interesting theory but I don't think it fits all the facts
(apart from I wouldn't describe the noise as a regular 'buzz buzz', I
don't imagine powering the unit off would make it go away). However,
you've got me sufficiently intrigued that I'm going to do some
experiments anyway, to see if I can reproduce /your/ problem.

No-one has said so explicitly, but I am getting the feeling that my
single-double insulated earth loop hypothesis is generally regarded as
a non-starter ...
!