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Thread: RV: Converter problems?

  1. #1
    Art Todesco
    Guest Art Todesco's Avatar

    Default RV: Converter problems?

    On 3/3/2010 4:33 PM, Frank Tabor wrote:
    > On Wed, 03 Mar 2010 14:53:44 -0600, Elliot Richmond wrote:
    >
    >> Still another question.
    >>
    >> We have a tiny trailer, so I recently purchased a tiny DVD player, a
    >> SuperSonic SC-28B Compact Portable CD DVD Media Player. It has a variety
    >> of inputs and A/V outputs, and works great. I also purchased an equally
    >> tiny nine inch digital TV that has a built in rechargeable battery and
    >> can use 12 volt adapter. . Last night, I tried the system out running
    >> everything from the 12 volt outlets in the trailer, and I was getting a
    >> 60 Hz buzz from the TV speakers. It was more of a buzz than a hum. The
    >> TV did not make this buzz when used by itself. It only made the noise
    >> when plugged into the DVD player. On a hunch, I went out and unplugged
    >> the shore power. The buzz went away.
    >>
    >> So, here is my question. Is noise normal on the 12-volt circuits when
    >> running the converter, or is the converter about to go on the fritz?
    >>
    >>
    >>
    >> Elliot Richmond
    >> Itinerant astronomy teacher

    >
    > Yeah, the converter probably doesn't have enough filtering/smoothing
    > capacitor on it. Instead of a flat 12vDC you are getting a 60 cycle wave
    > riding the 12v.
    >
    > Neon John will probably be along shortly to expound on it.
    >

    Not Neon, but I'll chime in here. This
    sounds like a classic ground loop. How
    are you connecting the DVD player to the
    TV/monitor? If using the "normal"
    video/audio leads, this can happen. I
    take it that the TV and the DVD were
    both running on 12 volts, right? I
    would try transformer isolation in the
    audio leads. I've done this in a number
    of places to eliminate this kind of hum.
    But, if all you care about is the
    ability to dry camp with the TV and DVD,
    you won't have power connected, so it
    shouldn't matter.

  2. #2
    Neon John
    Guest Neon John's Avatar

    Default RV: Converter problems?

    On Wed, 03 Mar 2010 14:53:44 -0600, Elliot Richmond
    <xmrichmond@xaustin.xrr.xcom> wrote:


    >So, here is my question. Is noise normal on the 12-volt circuits when
    >running the converter, or is the converter about to go on the fritz?


    What kind of converter do you have. The old Magnetek (6300?) has 2
    types of 12 volt outputs. Filtered and non-filtered. Normally the
    non-filtered power is run to the lights which don't require clean DC -
    at least until you change over to fluorescents. The filtered output
    goes to the radio if it is built in, the furnace and anything else
    that needs clean power.

    What you need to do is to figure out whether you have filtered power
    at the cig lighter jacks or not. If you have a fairly decent quality
    multi-meter, put it on the AC volts scale and look at the jack. If
    you see any significant reading then the DC is unfiltered. You should
    be able to move wires around back at the converter to get your jacks
    on filtered DC. Unless someone wired the jacks to the lighting
    circuit, of course.

    John

  3. #3
    richard
    Guest richard's Avatar

    Default RV: Converter problems?

    On Wed, 03 Mar 2010 14:53:44 -0600, Elliot Richmond wrote:

    > Still another question.
    >
    > We have a tiny trailer, so I recently purchased a tiny DVD player, a
    > SuperSonic SC-28B Compact Portable CD DVD Media Player. It has a
    > variety of inputs and A/V outputs, and works great. I also purchased
    > an equally tiny nine inch digital TV that has a built in rechargeable
    > battery and can use 12 volt adapter. . Last night, I tried the system
    > out running everything from the 12 volt outlets in the trailer, and I
    > was getting a 60 Hz buzz from the TV speakers. It was more of a buzz
    > than a hum. The TV did not make this buzz when used by itself. It only
    > made the noise when plugged into the DVD player. On a hunch, I went
    > out and unplugged the shore power. The buzz went away.
    >
    > So, here is my question. Is noise normal on the 12-volt circuits when
    > running the converter, or is the converter about to go on the fritz?
    >
    >
    >
    > Elliot Richmond
    > Itinerant astronomy teacher


    Buzzing usually is caused by one of two sources.
    A bad capacitor in the power supply, or bad grounding.
    Since this a new set, I'd suspect the grounding.
    The smaller the tv, the less they put in them.
    Try installing a ground lead from the tv to the chasis.
    You can also try installing a couple of clamp on ferite beads.

    But since you're also questioning the converter, it is highly possible that
    is the source of the buzz. If you have another vehicle, plug the set in the
    other vehicle and see what happens. No buzz? Converter.

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