Naveen91

Discussion in 'General Electronics Chat' started by kagustha, Jun 10, 2011.

is static electricity a great danger to Electronics?

  1. YES

    85.7%
  2. NO

    14.3%
  1. kagustha

    Thread Starter New Member

    Jun 10, 2011
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    I am new to this great site the "ALL ABOUT CIRCUITS". HELLO MY FRIENDS AND RESPECTED MASTERS Let us share our thoughts and ideas on repairing appliances and clarifying doubts

    My first set of doubts
    1. Why there is leakage of voltage on the DVD player body?
    2. Why there is no Earth pin in the plug of appliances like TV,DVD player,Set Top Box etc,.

    I assure you that I will be a Good member and friend to you.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Your subject title for this thread is confusing. It should actually be an introduction to what is contained in the thread, instead of some random characters. Perhaps it is another members' name?

    Your first question does not make much sense. Are you saying that you are getting shocks from a DVD player that is plugged into a wall outlet?

    The electronics inside the enclosures are supposed to be completely insulated from the enclosure itself, and/or the enclosure is made from a non-conductive material such as ABS plastic.
     
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  3. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    What is the benefit of running such a poll?

    Pose this question instead: do you think that if you stop breathing, your life is in danger?

    Nice start.
     
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  4. tom66

    Senior Member

    May 9, 2009
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    I've noticed that devices in plastic cases can have earth pins. I believe the reason for this is that there are class Y (line/neutral to earth) capacitors in these devices to reduce/filter out EMI. Presumably greater EMI is produced by a big TV set, but not by a DVD player.
     
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  5. Jotto

    Member

    Apr 1, 2011
    159
    17
    There is always leakage, just have to make sure its in the acceptable range. But its not voltage its current. Anyone repairing stuff in this area should test for leakage.

    I agree with SgtWookie on this, units are isolated to prevent this. If they were using earth and common ground there would be.
     
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  6. Jotto

    Member

    Apr 1, 2011
    159
    17
    This is a pdf of Standards for Leakage.

    I have to test for this on class II products. You are using a isolation transformer and testing the metal skin of the unit.

    NEVER TOUCH ANY METAL PART OF THE ISOLATION TRANSFORMER WHILE TOUCHING THE METAL CASE OF THE UNIT BEING TESTED.

    I have my unit set up in the shop that makes it impossible to do this, its too far to reach both units. But I have to take the unit to the floor and test there which doesn't allow this type of setup. Sometimes we get a complaint from a customer saying they were shocked and I test it to see if its in the acceptable range.

    I have found most have about .3ma or less.
     
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  7. kagustha

    Thread Starter New Member

    Jun 10, 2011
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    yes I am getting shock from dvd players can you tell me why it is so It is not only from dvd player but from many other such as set top, box TV input signal sockets etc., if you know the how to repair it please tell me.
     
  8. kagustha

    Thread Starter New Member

    Jun 10, 2011
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    yes I am getting shock from dvd players can you tell me why it is so It is not only from dvd player but from many other such as set top, box TV input signal sockets etc., if you know the how to repair it please tell me.
     
  9. electronis whiz

    Well-Known Member

    Jul 29, 2010
    519
    27
    If your getting shocks form all of these devices. I would say that one of them has a problem and it is putting a voltage on the cable connecting these devices together. Disconnect them from each other. then using a voltmeter put one lead of the voltmeter in the ground (the round slot) of an outlet. With the device to be tested pluged in place the other probe on the out side or inside contact or the ports that you were using to connect the 2 devices you get a shock from.
    If you can't or aren't comfortable doing this. An ohm meter may also work just put a probe on the thin prong of the plug (this is the hot prong) then test the ports if you get a low reading then that is probably the problem device. Do this for the other device also. If neither gets anything then you may want to try the wide pin this is the neutral pin. (however you may get a reading on the outside of a coax port because some times these are grounded.) Also most devices with 2 coax have the outer surface connected together so if you have 3+ devices in a series it could be any of them possibly.
    Also if your using an areal antenna check that for voltage also.
     
    Last edited: Feb 21, 2015
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  10. Jotto

    Member

    Apr 1, 2011
    159
    17
    I have been thinking about this. I think as stated by electronis whiz you have something wrong with a unit connected. Your primary or something in the primary circuit is leaking.

    I would disconnect one unit at at time till it stops. That should show you which one is the offending unit. Since there is no earth ground, which would be present in a three prong plug. Its sitting on the case and being feed to the other units via cables. You must also remove all the cables, not just the coax.
     
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  11. Wendy

    Moderator

    Mar 24, 2008
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  12. kagustha

    Thread Starter New Member

    Jun 10, 2011
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    Thank you very much for your kind replies and it is very much clear from the tests I carried out on my home entertainment systems That the leakage is due to the capacitor of 1mF 40V in the CRT TV near to the Audio video input pins (in my case).
     
  13. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Three years later? o_O
     
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  14. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    And a new record is set for OPs coming back to update a thread with results!
    Congradulations, Kagustha!
     
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  15. MaxHeadRoom

    Expert

    Jul 18, 2013
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    He just recovered!:eek:
    Max.
     
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