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AC Adapter Question

Discussion in 'Electronic Repair' started by Kevin Ross, Dec 12, 2004.

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  1. Kevin Ross

    Kevin Ross Guest

    I have a device (a Roland TR-505 drum machine) that works only on batteries. When I insert the AC adapter (the original, which obviously worked at one time) the device shuts down. The AC adapter appears to be converting the correct voltage at the plug. I don't know much about testing circuit boards. Any ideas as to why this pattern is occurring? Any leads on what I might do to figure out how to repair device without spending a lot of money. It's an old device but it does it's job well and suits my needs when it is working correctly.
     
  2. Jerry G.

    Jerry G. Guest

    Do you have a Volt meter to test that there is at least the proper
    voltage coming out from the adaptor? It would be best to test it while
    it is connected to the drum machine, so that it is properly loaded. A
    no load test may not indicate its true performance.

    If the adaptor is working, then check for any opened connections such as
    bad contacts, connector(s), and etc in the electrical path from the
    adaptor in to the drum machine.

    The next step would be to troubleshoot the electronics of the devices in
    question, which is something that cannot be done over an email. At this
    point, you will have to give it out, unless you are trained, tooled up,
    and experienced at this sort of work.

    --

    Jerry G.
    ======

    I have a device (a Roland TR-505 drum machine) that works only on
    batteries. When I insert the AC adapter (the original, which obviously
    worked at one time) the device shuts down. The AC adapter appears to be
    converting the correct voltage at the plug. I don't know much about
    testing circuit boards. Any ideas as to why this pattern is occurring?
    Any leads on what I might do to figure out how to repair device without
    spending a lot of money. It's an old device but it does it's job well
    and suits my needs when it is working correctly.
     
  3. Ken

    Ken Guest

    If the unit works on batteries but not on the adapter, then it is
    probably safe to assume that the power the unit needs is not being
    provided by the adapter. This could be due to a faulty adapter or a
    regulator circuit in the unit that is not converting the input from the
    adapter properly. There might be a bad rectifier, bad capacitor, open
    conductor, or any number of faults even if the adapter is good. Only by
    opening up the unit and taking measurements can you arrive at the reason
    it will not work with the adapter.
     
  4. Guest

    There is one thing to check first. Most of the time, there is a small
    switch to switch of battery power when you connect an adapter. This
    switch is often integrated in the connector, and could be open.
     
  5. Asimov

    Asimov Guest

    "Kevin Ross" bravely wrote to "All" (12 Dec 04 12:42:17)
    --- on the heady topic of "AC Adapter Question"

    KR> From: "Kevin Ross" <>

    KR> This is a multi-part message in MIME format.

    Use only ASCII text, not MIME encoded, on usergroups, please!


    KR> I have a device (a Roland TR-505 drum machine) that works only on
    KR> batteries. When I insert the AC adapter (the original, which obviously
    KR> worked at one time) the device shuts down. The AC adapter appears to
    KR> be converting the correct voltage at the plug. I don't know much about
    KR> testing circuit boards. Any ideas as to why this pattern is occurring?
    KR> Any leads on what I might do to figure out how to repair device
    KR> without spending a lot of money. It's an old device but it does it's
    KR> job well and suits my needs when it is working correctly.

    I have had a TR-505. You can test your adaptor with a 100 ohm resistor
    and a DC voltmeter. If it reads very low then the adaptor is bad.
    There may be a broken rectifier or the filter cap is dry. However,
    what you may have is a problem with the adaptor plug battery switch.
    It may be simply dirty, so try inserting and removing the plug a few
    times. It may also be damaged or have a broken solder pad. This could
    be fairly hard to fix if you are not experienced in mechanical things.
    To get at the jack the main circuit board has to be removed but it is
    a tricky job that requires some experience to know what you're doing
    or you might damage the pots or the LCD display. If you don't know how
    to solder then do not pass GO, and don't even reach for a screwdriver.
    This is vintage 8 bit stuff... ;-)

    A*s*i*m*o*v

    .... If plugging it in doesn't help, turn it on.
     
  6. Guest

    There is one thing to check first. Most of the time, there is a small
    switch to switch off battery power when you connect an adapter. This
    switch is often integrated in the connector, and could be open.
     
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