Tingles from DVD players

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Hi,  I just did a round of "kerbside shopping" and picked up 2x Digitor DVD
players from the same place. They both work. The only thing I can think is
that they give you a small shock between their chassis and power earth. I
can only surmise that the owner thought they were faulty and ditched them as
a result. I have picked up another DVD player in similar circunstances,
going, but tingling.
I believe the shock would be some capacitive coupling to their chassis from
the switchmode PS. I can measure 105 volts AC from their chassis to earth,
but no current .
Is there any rule that stops you earthing these devices, given that the
connection via the signal leads to an earthed amp etc would probably do this
anyway?
Do the manufacturers expect all devices to be turned off so that customers
don't experience shocks when changing leads around? If chassis earthing
elminates this issue, then it would be a nice feature and customer friendly
to do so. I guess the amount of copper / star washer etc saved per unit for
them outweighs thoughts for the customer.
Any comments?

Russell



Re: Tingles from DVD players



"Russ_Verdon"
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** Yes  -  the units are not longer "double insulated" or of "class 2"
construction if you substitute a 3 core lead.


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**  Only a few folk feel any tingle at all.


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**  Completely silly.

The use of Class 2 construction is a VERY deliberate decision and for very
good reasons.


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**  Absolute crapology.

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**  You seriously temp me.

 Never heard of earth loop hum  ?????




.........  Phil




Re: Tingles from DVD players



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Sure, that seems obvious.  The device would then be modified, the original
electrical approval would not be valid, and it would not be possible to
approve the device as a class 2 device with the case earthed.  Are you
aware of any technical reason why the device could not be approved as a
class 1 device (hypothetically, since the cost of testing would be more
than prohibitive)?  To the best of my knowledge the insulation requirements
of a class 2 device are more strict than would be required for a class 1
device, though I don't know if there are any fusing requirements for class
1 which would not have applied to the class 2 device when it was built.

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Apart from the earth loop hum you refer to, what reasons are you referring
to?

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Chris



Re: Tingles from DVD players



"Chris Jones"
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 **  You have completely missed the point.


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 **  Correct -  so the markings on the unit (ie  "class 2" and the double
square symbols)  would be then ILLEGAL.


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**  Yawn.

This is an entirely separate issue to the OP's question AND  my reply.



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** 1. Class 2 construction is far SAFER for the user.

2. Class 2 construction meets world wide electrical approvals making it far
easier for makers to market the same design world wide.

3. The use of class 2 is almost universal for some classes of electronic
equipment.

4. There is a PROHIBITION on interconnecting class 1 and class 2 equipment.





........  Phil





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like a laplink cable?

Bye.
   Jasen

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**  Piss off   -   kiwi tenth wit.

  The sheep are missing you.





.......  Phil



Re: Tingles from DVD players



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Ok but I was interested, in case you know something about it that I could
learn from.  I agree that I am slightly changing the subject, however I
thought it worth asking since the OP or others in a similar position might
be inclined to do whatever they feel like, provided they think it is safe,
but in spite of the law.  If there were a serious technical reason why it
would be unsafe, rather than a (re)labelling or legal issue then it would
be good to be aware of it.

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I am surprised by (4) since many hi-fi amplifiers (at least older ones) do
have an earthed case, for better or for worse.  It is not made very clear
to the average user that connecting the amplifier to a typical (class 2) CD
player would be prohibited, for example I haven't seen such a warning in
the instruction manual of a CD player.  I don't have the necessary
knowledge of the standards to refute what you say, but it does surprise me.
Perhaps you mean something different when you say 'interconnecting' from
what I had interpreted, i.e. connecting a shielded audio cable between two
devices, thus connecting their metal cases together.  Anyway thanks for
your answer.

Chris


Re: Tingles from DVD players



"Chris Jones"



**  Do you constantly move the goalposts at sporting events too  ?





..........  Phil



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I don't consider posting to usenet to be a competition, though you are free
to consider it whatever you want.  I just like to learn stuff.

Chris

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"Chris Jones"
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 >
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** Then why keep moving the goal posts like is is one you cannot bear to
loose ??



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**  If you mean that, then why make it impossible for anyone to answer you ?




........  Phil







Re: Tingles from DVD players



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When I change the topic, it has not been with the intention of winning or
avoiding "loosing" (or even losing) an argument.  I don't like being wrong
but the only way around that is to learn more.  If I think I have nothing
to add on a particular topic then I don't write anything about it.  If it
leads me to think about a different topic that interests me then I will ask
or comment about that.  You have posted some thought-provoking replies and
I thank you for that. I know more than I used to about a couple of things.

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I think you have managed ok.


Re: Tingles from DVD players



"Chris Jones"
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** Making a task unnecessarily difficult for someone else is the act of
complete asshole.

    Bing smug about it is even worse.



........  Phil



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"Chris Jones"
 Phil Allison wrote:

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**  Have you never seen the words " Double Insulated - Do Not Earth "  on
the back of a class 2 item ??

     Pretty clear isn't it?


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**  It is not prohibited by criminal law -  so no police officer will arrest
you for doing it.

But it is an * unsafe practice* that could be considered as " serious
negligence " by a court if a person were injured or killed.


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** " Double Insulated - Do Not Earth "  on the back of the player is a
*stronger warning*  that anything printed in a user manual that likely gets
lost with the packaging.

Equipment makers are not liable for what users may WRONGLY do when
interconnecting items of gear  -  so just ignore the issue.

The matter is very much an  *X rated topic * in the home entertainment
electronics industry.


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** Imagine a hi-fi system with every item in it class 2  - so there is no AC
ground to the metalwork.

Next, an item is added to the system, ie a nice old valve tuner just bought
from Ebay but with no AC plug.

Next, the user inadvertently wires up the new plug wrongly with active and
earth reversed and makes all the connections.

The hi-fi system will still work just as before ( but not the tuner) but
with ALL the metalwork, connecting leads and even the loud speakers now
LIVE  !!!

In countries with 240 volt AC power, this is a FATAL  accident scenario
!!!!


NOTE:

One of the BIGGEST  user safety advantages of class 2 construction is that
no matter how WRONGLY the AC plug is wired & no matter what is wrong with
the AC outlet,  you cannot get active onto the earth of the gear.




........  Phil



Re: Tingles from DVD players


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a major advantage of class 2 is that its cheaper. the plug, cable and
interconnects cost less, and because of the double insulation, none of
the metalwork has to be earthed, which it does with class 1 - for many
standards the metalwork earthing must carry the rated current, further
increasing the cost.

The above scenario can only happen when people fiddle with things, and
so is not relevant to manufacturers (they build them right). Such a
scenario also occurs with a single class 1 appliance wired up by the
same dickhead. Voila, live chassis (and dead operator).

Cheers
Terry





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"Terry Given"


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** Bullshit it is.

The specs for the AC supply transformer alone are way beyond that for class
1.

The design rules for every part of the AC side are way tougher.


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**  By a few cents only.


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** What absolute drivel.


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**  More " Pinball Wizard " bullshit.


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**  It is  *very elevata" to the increased safety of class 2.

 It is  *very relevant" to the PROHIBITION on earthing a class 2 appliance.



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** But  NOT  a system of interconnected class 1 appliances.

Hence the prohibition on earthing a class 2 appliance or system thereof.

They are very safe until you do that.



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**  Please go try it now.




.......  Phil



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double insulation pretty much means 2 sets of insulation, so that when
one fails there is still one left. yes the xfmr is a bit more expensive,
but a whole bunch of other stuff gets cheaper.

look inside a hair dryer, that is far, far cheaper as a class 2 device
than class 1.


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not really, and they are made easier by the proliferation of plastic.

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why do you think they use phenolic paper PCBs, and an interseting mix of
1%, 5%, 10% and 20% components? when you build 500,000,000 of something,
all them cents add up.


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Phil has obviously never read BS-EN61010

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depends on the system, and how they are interconnected.

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Cheers
Terry

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"The Pinball Wizard of  Nelson "


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 **  Absolute bullshit.


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 **  Absolute bullshit.


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**  Much more -  the cheapest construction methods are outlawed.

    The popular and cheap toroidal is basically outlawed.



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**  Absolute bullshit.


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**  The subject is DVD players and the like -  fuckhead.


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**  Get stuffed    -  Kiwi LIAR !!




.......    Phil




Re: Tingles from DVD players


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ROTFLMAO! You are demonstrably wrong, viz.:


first, lets un-snip what I posted:

"double insulation pretty much means 2 sets of insulation, so that when
one fails there is still one left"


AS/NZS3000:2000 Wiring Rules states:

1.4.26  Class II equipment -
Equipment in which protection against electric shock does not rely on
basic insulation only, but in which additional safety precautions such
as double insulation or reinforced insulation are provided, there being
no provision for protective earthing or reliance upon installation
conditions


1.4.57 Insulation System
One, or a combination of, the following:
(a) Basic Insulation - the insulation applied to live parts, to provide
basic protection against electric shock
(b) Supplementary Insulation - an independant insulation applied in
addition to basic insulation in order to ensure protection against
electric shock in the event of a failure of the Basic Insulation
(c) Double Insulation - insulation comprising both Basic Insulation and
Supplementary Insulation

In other words, exactly what I said.

Bwahahahahaha!

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pah. look at those sorts of xfmrs, its not very complex. split bobbins
with lids basically, and a bit more creepage/clearance. they still wind
them with magnet wire; I've yet to see a consumer xfmr wound with
Furukawa Tex-E or any other form of triple-insulated wire....

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on what basis?

and toroids are not that cheap to wind c.f. an e-core bobbin, especially
the little ones (and the big ones)

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Cheers
Terry

Re: Tingles from DVD players


On Wed, 22 Mar 2006 12:35:28 +1100, "Phil Allison"

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I've just checked all the double insulated items in my home  and NONE
of them carry a warning such as you describe. It would be useful to
know how general such a warning is. I suggest everyone reading this
thread check their equipment and report back their findings. My
equipment includes items from NEC, Philips, Sony, Teac, Mitsubishi,
Sanyo & Microsoft.

snip

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So where does the  "PROHIBITION" come from?
Previously you said such interconnection was prohibited, now you're
saying to ignore the issue??

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If this danger was significant then the use of Class 2 equipment is
inherently unsafe because it would be relying on user action to make
it safe, the user action being to not interconnect with other commonly
available items. As you say above, "Equipment makers are not liable
for what users may WRONGLY do.....", but regulators are always
interested in such things. They seem relaxed about the situation.

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--
Regards
Malcolm
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"Malcolm Moore"
 "Phil Allison"

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** The warning notice is not compulsory.

Only the use of the  "double square" symbol or the words "Double Insulated"
are.


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** The fact that a class 2 appliance must not be earthed.


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** Huh   ???

 What madman's logic is this  ?

 What the hell do you think "X -rated " means ???



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**  Absolute drivel.

Class 2 construction appliances are inherently much safer than class 1
types.

What users do that  COMPROMISES that additional safety is beyond the control
of makers or authorities.


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**  SFA they can do about it.

The issue is one of legal liability on the part of someone who elects to
earth a class 2 item.



........  Phil




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