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dirty DC power input

Discussion in 'Electronic Repair' started by VM, Mar 5, 2006.

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  1. VM

    VM Guest

    Hi,
    I'm a total electronics newbie, so forgive the ignorance! I have just
    gotten a device (a drum machine) with an apparently dirty DC input
    power socket. Using a 9V AC-DC adapter, the unit works, but only when
    the connector is just in the RIGHT position. Otherwise the thing
    doesn't turn on. How does on go about cleaning out one of these jacks?
    The jack is not loose or anything and fits the plug very tightly, but
    the slightest movement can cut the power. Any suggestions?


    Also, while I'm here, can any damage be done by using a 300 mA adapter
    on equipment that requires only 50 mA? Again, total newbie here, but
    using this adapter on the drum machine hasn't hurt it (yet!). Thanks
    in advance.
     
  2. Mr Fixit

    Mr Fixit Guest

    its more than likely its a either a broken joint on the PCB or cable
     
  3. G

    G Guest

    Howdy! No need to apologize for asking a question!. The most likely
    suspects for your intermittent power with that AC-DC adapter are
    that you may have an adapter plug (if coaxial) with a center female
    that's too large OR that the coaxial type power jack (I'm assuming
    that's what you have) has a poor "switched" contact inside it which is
    also very common. Does this unit have provision for internal batteries?
    As to your second request regarding the use of a power cube rated
    apparently at the same voltage but higher current, the answer is
    "maybe". The reason here is that many (most) of these adapters are
    unregulated and are nominally rated for their voltage AT the rated
    current - so using it on a light load will often result in a
    significantly higher voltage (measure it to be sure under load.....using
    a subsitute resistance instead of your valued load is the best way to
    get a feeling for whether it'll be acceptable).

    Gord
     
  4. VM

    VM Guest

    Hi,
    thanks for the suggestions... I somehow doubt there's a connection
    broken as I can't see it ever being able to break in the first place
    i.e. the unit was never opened as far as I know. The too large center
    female maybe the problem (and I am using a universal, rather than
    device specific power supply), but looking at the jack, it is quite
    dirty, so I wonder is there a way to clean it up easily? and if so,
    would that help anything?

    The device DOES use batteries, but these are also not working at the
    moment. I cleaned up the blue gunk from the springs, but the negative
    (-) contacts are brown and dirty as well, so I guess there's no
    connection being made... I tried using an eraser to clean them, but to
    no avail. I don't know how else to clean these contacts. Any other
    suggestions?
     
  5. tvguy

    tvguy Guest

    Anonymouswrote
    Hi
    I don`t think you have a dirty plugin jack. I beleave it may have som
    bad solder connections where it is attached to the main powersuppl
    board or you may have a faulty 9 volt adaptor
     
  6. tvguy

    tvguy Guest

    Anonymouswrote
    Hi
    Doesn`t matter if the unit was open up before or not. These solde
    connections can come loose just by plugging the adaptor in and out
    This is a very common problem for these units that has an addaptor
    Either it has bad solder which I tink it does or the whole jack i
    bad and needs to be replaced completely. But I would suggest to hav
    it opened up even tho this will be the first time the unit ha
    everbeen opened up and have those solder connections checked
     
  7. VM

    VM Guest

    Thanks again for all the suggestions....
    I will definitely have a look at the soldering. I am also ordering a
    unit specific power supply which is cheap enough to at least help rule
    out using the wrong sized connector.
     
  8. G

    G Guest

    Howdy again.....Reason I mentioned batteries is that many devices that
    use batteries along with a DC jack, often have the jack disconnect the
    batteries when the adapter is plugged in OR use the adapter to charge a
    NICAD pack with the device disconnected via the jack switched
    contact......I've often found that switched contact to be poor quality
    and a source of problems.
     
  9. Jamie

    Jamie Guest

    most likely a broken wire in the plug on the adapter or a inside
    you have a solder joint connection problme! most likely needs to be
    resoldered.
     
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