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Battery automatic cut off function

Discussion in 'Electronic Repair' started by Andy, Aug 22, 2007.

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  1. Andy

    Andy Guest

    I have a wireless portable sound system call a Paso 500 (http://
    www.pasosound.com/wpcs50.shtml). Its a great unit but it has an auto
    battery cut off when the battery starts going flat. Sounds ok but it
    really can cut out waaaaay before its due time. The same battery it
    cuts out will play on another brand's unit perfectly. My question is,
    can I remove this function and or can I adjust the cut off threshold
    for it.

    Thanks,
    Andy
     
  2. Probably to keep it on frequency, etc. That another brand works to a lower
    voltage is neither here or there.
     
  3. Andy

    Andy Guest

    None the less I would love to know how to by pass it. It really isnt a
    good feature. It can cut off after 40 min. Any help would be great.

    Andy
     
  4. Ron(UK)

    Ron(UK) Guest

    Is it possible that you are using low quality or unsuitable batteries?

    Ron(UK)
     
  5. Andy

    Andy Guest

     
  6. Well I use radio mics for a living and I always replace the batteries
    before they fail. You get to know how long they last. It sounds like this
    battery is running a power amp so the life will vary with load. So replace
    it for the worse condition. I'd say it's likely they have a very good
    reason for this auto cutoff at this battery voltage. You can't just magic
    that reason away. If the life isn't long enough use a larger external
    battery.
     
  7. Andy

    Andy Guest


    Can anyone answer my question though. I fully understand the situation
    (I shouldnt do it, its under powered, its there for a reason). Let me
    just start again as people are getting hung up on the background. here
    another scenario: "A person made an amp with an auto batt cut off and
    I purchased it and wanted to remove it".
     
  8. Arfa Daily

    Arfa Daily Guest

    OK then. How does it cut off ? Is the power to the main board controlled via
    a relay, that opens when it detects the low battery condition ? Or does it
    just cut off silently ? If the former, then it is easy enough to just short
    the relay conatcts. If the latter, then you need to locate the switching
    transistor that controls the feed. This should not be too difficult. I would
    expect it to be either one of the larger D-line package transistors at a
    minimum, or some type of flatpak package like a TO220. It should be easy
    enough to follow the battery "+" around the board until you arrive at such a
    transistor. Once found, it should only be necessary to short its collector
    and emitter pins, to effect a bypass. If you want to get a bit cleverer,
    locate the sensing circuit, which is likely based on either an opamp wired
    as a comparator, or an actual comparator IC, and alter the threshold set
    point resistor(s)

    Arfa
     
  9. Andy

    Andy Guest

     
  10. Arfa Daily

    Arfa Daily Guest

     
  11. Gary Tait

    Gary Tait Guest

    Either a potentionmeter or a couple fixed resistors.
     
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