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Electric Shock ?

Discussion in 'Electronic Repair' started by [email protected], Feb 12, 2006.

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  1. Guest

    Hallo members, my Philips brand of DVD player have some kinds of
    electric shock if you
    touch the metal panel. I measure the leakage voltage is 125 volts but
    the leakage current
    is too small to kill a person. I 'm curious to know is this normal as
    the power cord is two pin
    and this also happen when it is a new set .Thanks
    Regards
     
  2. Not enough current to kill? Must be a design defect.

    Mark Z.
     
  3. Michael Ware

    Michael Ware Guest

    Could be a wiring fault in the outlet, neutral and hot reversed. Try
    plugging it in another room.
     
  4. It's common these days - usually RFI suppression.
     
  5. default

    default Guest

    A DVD player that shocks normal? Categorically: not normal.

    It is possible that some power line filter cap is leaking enough to
    the chassis to cause something like that, but I find it hard to
    believe Philips would allow that in a consumer item. They'd change
    the design. That sort of thing is bad for business.

    Reverse the plug in the socket and see if it goes away.

    Don't ignore it. Make sure it is the DVD player and not the TV or HI
    FI that's plugged into it that is causing the problem.

    If it is the DVD player, or other component, you really can't just
    hope it won't get worse - there may be some failing insulation and it
    is just possible that some circumstance (high temperature, wet floor,
    humidity, a different outlet, time, etc.) will make it lethal.

    BTW you don't say what your line voltage is. If it is 220 and you get
    ~125 that lends some credence to it being a power line filter.

    Treat it like it is lethal until you know how to fix it. If all else
    fails, ground the sucker to a good ground. If you just bought it take
    it back and get one that doesn't shock, or get a different brand.
     
  6. Guest

    Is this a single shock that you no longer feel as a tingle once you
    have your hand on the unit?
    If yes, then it is common static build up, probably on your body that
    is discharging to the path through the metal case.

    If it is a continuous tingle, then there may be some leakage current in
    the device.

    Simply disconnect the dvd player from all other devices (tv, audio,
    etc), plus it in, and measure the voltage between the metal case and
    ground with a 1K ohm resistor across the meter leads. If you still
    measure a significant voltage across the 1K ohm resistor, then there is
    a problem in the dvd player. Then reconnect it to everything else, if
    you now measure a significant voltage across the 1K ohm resistor, then
    you have a problem with another device that is connected to the DVD
    player.
     
  7. Guest

    It's normal for most equipment with switching power supplies to have
    some relatively studly capacitors across the AC line, center tap to
    chassis. This is supposed to be to keep any RFI generated inside the
    box from leaking back out through the power cord, and vice-versa.

    Older equipment tended to have much smaller capacitors, on the order of
    0.005uF, which could still give you a very mild tingle, but nothing
    like what you get from todays capacitors-- I've seen up to 0.1uf to
    ground, 0.47uF across the line.
     
  8. How did you determine the leakage current? Is it on the same outlet that
    you experienced the shock?

    Leonard
     
  9. Jerry G.

    Jerry G. Guest

    What you are describing is not right. Check if the AC outlet is wired
    correctly. If so, then have the appliance's power supply checked for
    ground faults.

    Jerry G.
     
  10. Mr Fixit

    Mr Fixit Guest

    its going to have a earth fault as it does not have one??
    I would disconnect all cables apart from the mains and then measure it as it
    could be the tv or video ETC
     
  11. Guest

    Thanks members for the early responed, and my further finding for
    member's questions is:
    (1) The DVD player's input voltage is 240 V AC.
    (2)When reverse the plug in the socket will reduce to 60 volts AC
    leakage
    (3) When I measure a cross with 1 K resistor the leakage voltage become
    zero volt.
    (4)When measure between the earth and the metal panel is 0.04 in ma
    range but 137 in ua range. unknow why resultant is different. ?
    (5) When measure between the earth and the power input ( two pin )
    there isn't any ohm.
    (6) It is not a Single shock
    Regards
     
  12. default

    default Guest

    That would bother me the RFI caps on switching supplies should divide
    the voltage equally since they tend to be identical to the "ground"
    chassis connection.
    That's good.
    That's not what I'd expect, but this isn't a hard connection. You
    seem to be measuring the voltage through a capacitor and/or resistor
    in the RFI filter.
    Shouldn't be, but the type of tester you should be using is called a
    hi pot or high potential tester and that would tell you if it is safe
    or insulation breaks down with high applied voltage - the typical ohm
    meter may not be the best tool to check ohms or safety.
    I'm guessing you have an IEC power cord? Thingee that is designed for
    three wires? And you've gone and cut the ground off?

    You are probably "safe," at the moment at least. It may be safe
    indefinitely. Safety devices are to protect you when things go wrong.

    If it were me I'd ground it and wouldn't be using it without a ground.
    If I couldn't ground it (in an apartment with no access to a ground,
    for instance) I'd take care that the parts I touched were insulated.
     
  13. Guest

    I comfirm that is a two pin power core.
     
  14. default

    default Guest

    Describe the plug end and machine end. Are the pins in the plug
    round or flat? Is there any other thing (like small piece of metal on
    the plug with a hole in it) on the plug end?

    Does the machine end have an IEC connector? Machine end would be a
    recessed, keyed (only goes in one way) male on the machine female on
    the cord.

    What has me baffled is that the whole purpose of a filter with caps or
    resistors in it (the part causing the shocks) is to filter noise to
    ground. Most filter line-to-line and each line-to-ground.

    Now without providing a ground . . . how's the noise supposed to drain
    to ground? Presumably they could count on the TV or Stereo to do it
    but that's not in any safety specification I've seen.
     
  15. Guest

    Hi morning., thanks for your reply. It just a two hollow pins inlet at
    the back of the dvd player, as most of our members belive may cause by
    filter circuit, I will open the dvd layer look for the filter. I would
    like to said big thank you for members who responed in this topic &
    happy valentime day.
    Regards
     
  16. Mr Fixit

    Mr Fixit Guest

    in the UK we have two pin figure of 8 connectors like this
    http://www.itx-warehouse.co.uk/Product.aspx?ProductID=475
    its a two core cable no earth and not keyed so you can plug it in both ways
    and quite happily plug live to neutral and visa versa
     
  17. default

    default Guest

    From your link:

    "Description Generic Main lead - UK to Figure 8
    Mains lead with UK style 3 pin plug, terminated with Figure 8 style
    moulded connector."

    Says three pin plug.

    We (US) had some plugs shipped over here that were supposed to be for
    the UK at a place I worked. They were large round molded bodies with
    two smooth polished round pins and the pins had insulating sleeves
    near the plug body. They had three wires blue, brown, green/yellow
    and an IEC connector at one end.

    There was a third flat metal piece on the plug that had a round hole
    that went through the plug body. It was connected to ground and its
    purpose seemed to be to add a pin or perhaps a screw to keep the plug
    in place? Just speculating . . .

    I was on line looking for UK electrical requirements. They seem to be
    the same as here in the states. Three wires with a hot neutral and
    ground . . . only difference I saw was in the wiring of electrical
    light switches they don't show the ground going to the switch -
    perhaps that was an oversimplification.

    We have some two wire appliances with GFI protection built into the
    plugs and "wall wart" switching supplies with only two wires.
    Computers are three wire. The area I live at has adapted an
    electrical code that requires four wires on 240 volt electric stoves.

    There's still a lot of two wire appliances - many of those have
    all-plastic bodies. Houses and new construction here require GFI
    protection on outlets outside the house, in most garages, all
    bathrooms and kitchens, on hot tubs etc..

    Workplace safety hasn't caught up - I tried to promote GFI's in a
    laboratory where I worked - we had large volumes of water (and
    electrolytes) and lots of electrical equipment. It wasn't required,
    so they wouldn't do it, but they put one on my workbench because I
    worked on the equipment - and I didn't ask for it, had no water
    nearby, etc..

    I inadvertently got connected to a leaky coffee maker - the GFI
    tripped and I could feel the current. Just now put a 12K resistor
    across the hot to ground and tripped the GFI - instantly.

    UL rules here: GFI required to trip at
    6 milliamps within 5.6 seconds
    50 ma in 270 milliseconds
    100 ma in 100 milliseconds
    250 ma in 27 milliseconds

    In practice, 6 milliamps will cause a trip in 50 milliseconds or less.
     
  18. Mr Fixit

    Mr Fixit Guest

    correct all our outlet plugs have three pins but not all are used as all our
    cables are not three core?? we have two and 3 core cable there are two pin
    plugs that look like an 8 hence the term "figure of 8 style" that plug into
    the equipment that have no earth requirement or are double insulated
     
  19. Yehbut figure of 8 is two. For domestic use all UK plugs are three pin,
    but if the device conforms to the appropriate regs the cord may well be
    just two.
     
  20. Line neutral and earth in the UK. And neutral and earth are connected
    together at some point - but not at the actual appliance. Either the
    nearest substation or where the supply comes into the house - in some
    cases. So only the line is 'hot' although in practice there may be a small
    potential between neutral and earth in some installations.

    With lighting, the neutral doesn't usually go to the switch enclosure, but
    the earth does.
     
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