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Problem with DC/AC Power converter

skinjskinj Posts: 3,383
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in TV and Home Entertainment Technology #1
Hi guys.

Am planning on taking my an LCD TV, my car, some mates and lots of beer to a sunny park somewhere on Sunday to watch the football without the massed crowd of the pub to deal with.
I have a Skytronic 300watt inverter to hook up to the car battery and have checked that the LCD will not draw more than 300watts. I just tested it as a dry run and it worked, except the TV was making what I can only describe as a very quick repetitive clicking noise that is relativley loud. I have the pos/neg terminals the right way round and have run the earth lead to the car chasis. The set ran on normal mains before perfectley and is again now.
My question is, is this type of noise normal when using this type of converter and/or will I be damaging the TV if I carry on and use it anyway?

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    grahamlthompsongrahamlthompson Posts: 18,486
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    #2
    Try seperating the inverter as far as possible from the TV and especially the aerial. it's probably generating lot's of RF
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    [Deleted User][Deleted User] Posts: 5,383
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    #3
    Why have you run the earth lead to the car chassis? - that's at negative voltage, -12V DC! Disconnect it.

    Cars have one side of the battery, usually the positive {+ve} side) connected to the equipment (lights, horn, radio) etc and the other, negative {-ve} side to the chassis - saves having to run lots of wires back & forth , you just connect the -ve lead of the equipment to the chassis to complete the circuit. It's called "negative earth" - Google it.
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    skinjskinj Posts: 3,383
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    #4
    Hi the noise is notcoming from the speakers, and no rf lead was plugged in. The noise was there when the set was plugged in directly to the inverter or via a 15m extension. It sounds very much like a psu issue or similar. The clicking/buzzing noise comes mainly from the TV but the inverter itself seems to echo it but to a much lower degree. If the TV is fully off the noise stops but as soon as you power up it reappears.
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    skinjskinj Posts: 3,383
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    #5
    LCDMAN wrote: »
    Why have you run the earth lead to the car chassis? - that's at negative voltage, -12V DC! Disconnect it.

    Cars have one side of the battery, usually the positive {+ve} side) connected to the equipment (lights, horn, radio) etc and the other, negative {-ve} side to the chassis - saves having to run lots of wires back & forth , you just connect the -ve lead of the equipment to the chassis to complete the circuit. It's called "negative earth" - Google it.

    Aware off negative earth, have been setting up car audio for years using neg' earth however the instructions say to hook up the pos', neg & earth this way or the earth direct to ground (not sure how this would be done) see page 3 http://www.tlc-direct.co.uk/Technical/DataSheets/Inverters/TLINV150x.pdf
    have tried it both ways.
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    skinjskinj Posts: 3,383
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    #6
    For more details, the LCD I hooked up was a Panasonic TX26LMD70, the Skytronic inverter and a Ford Focus.
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    Nigel GoodwinNigel Goodwin Posts: 58,518
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    #7
    Cheap inverters output squarewaves, most electronic equipment doesn't like been fed a squarewave. The best ones (but very expensive) provide sinewaves, but you can get medium priced ones that provide 'modified sinewaves' - which may be OK.
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    skinjskinj Posts: 3,383
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    #8
    The inverter being used is providing a modified sinewave which after looking around the web should be ok for a TV.
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    brillopadbrillopad Posts: 3,226
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    #9
    What's the exact model No of the inverter ?
    I see 'soft start' is recommended for powering TVs
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    skinjskinj Posts: 3,383
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    #10
    It's the 651.626, 300w unit. The soft start is basically allowing the inverter to power up before switching on the appliance. Either way still buzzes/clicks
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    brillopadbrillopad Posts: 3,226
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    #11
    skinj wrote: »
    It's the 651.626, 300w unit. The soft start is basically allowing the inverter to power up before switching on the appliance. Either way still buzzes/clicks

    In case you don't have it here's the manual

    I see the current drain of this thing is massive and they say you might need to run the engine as well.

    " Try running the vehicle engine while running the inverter. (REMEMBER to switch OFF the inverter when starting the engine.) This will boost the battery voltage allowing the inverter to operate more efficiently, allowing use of the inverter for longer periods of time in high load applitcations."
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    skinjskinj Posts: 3,383
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    #12
    Cheers but I posted that link earlier on and I'm having no problems with power drain or the soft start. The issue is the noise the TV makes when connected to the inverter.
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    webbiewebbie Posts: 1,614
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    #13
    I would suggest that your tv doesn't like the modified sine wave. The power adaptor will be generating all sorts of rf noise and this is going through your tv's power supply and getting to the speakers. One thing you could try is a mains filter on the tv's mains input to try to filter out this noise - have you got an extension lead with a built in filter to try? A lot of mains filters require a proper earth connection to work properly but you may get lucky.
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    skinjskinj Posts: 3,383
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    #14
    The noise is not coming from the speakers it is from the rear of the set and as mentioned earlier sounds like a psu related noise. The speakers are fine.
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    webbiewebbie Posts: 1,614
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    #15
    OK, but it's still noise generated from the adaptor that is interfering with the filter in the psu of the tv. It really needs filtering out with a mains filter or using a power adaptor that gives out a true sine wave. If you have a mains adaptor/extension lead with a filter built-in, try that.
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    skinjskinj Posts: 3,383
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    #16
    Ok will see what I can russle up.
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    webbiewebbie Posts: 1,614
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    #17
    No guarantees! If you have an extension lead with a filter it may require an Earth connection.
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    Nigel GoodwinNigel Goodwin Posts: 58,518
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    #18
    skinj wrote: »
    The noise is not coming from the speakers it is from the rear of the set and as mentioned earlier sounds like a psu related noise. The speakers are fine.

    It'll probably be coming from the filter components in the TV, not liking the non-sinewave input.
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    skinjskinj Posts: 3,383
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    #19
    Resolved issue. Mate at work has a petrol generator that I'll use ionstead, Cheers all.
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    pocatellopocatello Posts: 8,813
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    #20
    Nigel Goodwin wrote: »
    Cheap inverters output squarewaves, most electronic equipment doesn't like been fed a squarewave. The best ones (but very expensive) provide sinewaves, but you can get medium priced ones that provide 'modified sinewaves' - which may be OK.

    bingo
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