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Thread: Bizzare problem

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    Default Bizzare problem

    I'm not sure if this is the right spot for this but I'll give it a go.
    I have a 65cm dish mounted on a star picket for my selectv sub. Not an ideal setup and as such I have to realign the dish every so often, but its no big deal.
    Until last night. I turned off the stb (Strong 4658x) and went outside to connect the satellite meter to the lnb. I grabbed the f connector to disconnect it from the lnb - and I got a shock.

    I thought it was strange as there should have been no power to the lnb with the stb switched off. To be sure I unplugged the stb and grabbed the connector again. Got another belt! So I grabbed my multimeter and found 105v AC between the coax cable and ground. With the stb unplugged I couldn't for the life of me work out where the hell it was coming from. The coax doesn't run in close proximity for any distance near any power cables to be picking up induction.

    The only place I figured it could come from was via the RCA cables that run from the stb to a selector switch and then to a VCR. Sure enough there was 104V~AC on the white audio cable and also on the yellow video cable.

    But beyond that I cannot find where it is coming from. I also have a terrestrial stb and a dvd player connected to the selector switch and I thought I could work out where it was coming from via a process of elimination. But no matter what I unplug and switch off I still have some crazy voltage on the RCA cables. Sometimes its 54vac and sometimes its 64vdc.

    Anyone struck this kind of issue before? I just can't work out what the hell is going on.



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    Are you in a duplex ?. Do you have a roof mounted tv aerial ?
    Could be the neighbour's tv or whatever has a fault that is putting some voltage to the mains earth.
    Unplug the aerial from your stb and see what your meter says.
    Last edited by dryfry; 29-08-10 at 03:02 AM.

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    Actually its a donger (granny flat) so there are no adjoining neighbours. There is a roof antenna and I tried disconnecting it but it made no difference.

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    thygreatone Get the VCR checked out by a technician before it starts putting 240 volts through its output sockets and into you.
    Maybe see about fitting an earthed lead to all of your gear..
    Floating voltages is the side effect of not having earthed equipment.

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    i seem to remember a thread about earthing lnb's.......

    I make up a special lead and earth all my a/v gear...
    Last edited by hoe; 29-08-10 at 11:39 PM.

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    I use to get a nice shock when playing with f connectors with all my sat gear (especially when being lazy and not turning off the power and connecting sat finders), but since earthing my Dreams LNB the problem has been taken care of.

    Your problem sounds like one of your joined units is putting power through one of the connectors from other equipment as mentioned by dryfry.
    Last edited by Godzilla; 30-08-10 at 12:44 AM.

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    Typical 2 pin power cord stuff...
    You could "earth" the CASE of your receiver to a 3 pin mains plug (but you have to be a licensed electrician to do that):P
    I did this regularly when I was a service tech. Mainly on TV's (some on VCR's) to stop (reduce) RFI from the switch mode supplies radiating from the house TV cable wiring to the antenna & getting into AM radios.
    ***NEVER EARTH THE CHASSIS OF A SWITCHMODE POWER SUPPLY***
    You will be severly hurt or DEAD
    With 7 sat dishes in the yard & 6 sat receivers, I'd say I'm serious about the hobby! Welcome to my own Pine Gap.

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    This might help you with an answer to your floating voltages.


    And that why they recommend turning off equipment before messing with wires and connections.





    Mickstv
    Last edited by mickstv; 30-08-10 at 12:16 PM.

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    Thanks everyone for all the advice. I guess I'll try earthing the shield of the cable for now. Although I mightn't use the dish for a while now seeing that Selectv is dead.

    Quote Originally Posted by vmark View Post
    Typical 2 pin power cord stuff...
    You could "earth" the CASE of your receiver to a 3 pin mains plug (but you have to be a licensed electrician to do that):P
    I did this regularly when I was a service tech. Mainly on TV's (some on VCR's) to stop (reduce) RFI from the switch mode supplies radiating from the house TV cable wiring to the antenna & getting into AM radios.
    ***NEVER EARTH THE CHASSIS OF A SWITCHMODE POWER SUPPLY***
    You will be severly hurt or DEAD
    As it happens I am on the way to becoming a licensed electrician(3rd year apprentice). But of course even though I have the knowledge (or more than most anyway) to be able earth appliances I am still unlicensed.

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    May that be a lesson to all.... signal from antennas & satellites travels along the cable via electricity. If you touch the ends of an antenna that is connected to a TV you will get a zap too!

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