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Wanted: information on charger for Rio S50 mp3 player

Discussion in 'Electronic Repair' started by Beloved Leader, Nov 15, 2013.

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  1. Hi. The RioS50 mp3 player was on the market some ten years ago. The owner'smanual and reviews are easily found online. I got one at a yard sale for not much money a few years back. It lacked the charger and the cable that allows one to download songs from a computer. "That's why it's so cheap," theseller said.

    Almost incredibly, I found the cable at a thrift store. iTunes recognizes the device, and it works with Rio's software as well. Storage is limited, but it has an FM radio. It still works, and I still use it.

    It was designed to run off a 1600 mAh NiMH cell. It can run off an alkalinecell or a NiCd cell too. Because I do not have the charger, I have to remove any rechargeable cell for recharging. Although the owner's manual and reviews are online, I have not found the details for the recharger. What was its output voltage? How much current did it supply? What was the size of the barrel connector? What was the polarity of the tip and the ring?

    If anyone can come up with that information, I would be grateful. The charger probably worked with other Rio players that ran off a single 1.25 volt or 1.50 volt cell.

    Thank you.
  2. Guest

    Probably more than 1.2 V. More below.
    The owner's manual says to charge the battery for at least 5 hours the
    first time. The supplied battery is (1.6 * 1.2) or 1.9 watt-hours
    nominal. If the five hours was a full charge, this implies that the
    charger supplies at least 0.38 watt.
    Go to Radio Shack and try their selection of Adaptaplugs until you find
    the one that fits. If you don't mind spending what they charge for
    adapters, buy a multi-output adapter and the Adaptaplug; otherwise tell
    them you already have the adapter and buy just the Adaptaplug (which is
    still a ripoff at $7). If you can solder, and the Adaptaplug happens to
    be one of the sizes they carry in a "regular" plug (in the drawers full
    of small parts), buy the "regular" plug instead; it's cheaper. If you
    can solder and it's a weird size, just solder to the Adaptaplug pins
    later. If you can't solder and it's a weird size, buy their 273-350
    cable for $5, to turn the Adaptaplug ends into wires.
    Go home and plug the plug into the MP3 player. Use a multimeter to
    measure the resistance between the negative battery contact and each pin
    of the DC plug in turn. One pin will probably show a low, constant
    resistance (less than 1 ohm.) This is the "negative" pin.

    Now you need a somewhat discharged NiMH cell, some fresh alkaline cells
    (AA size is fine, C or D will also work), tape (clear office type is
    fine, but anything will work), and wire. Put the NiMH cell in the MP3
    player. Tape a wire to the - side of one alkaline cell, and connect
    that wire to the "negative" pin of the DC power plug. Connect another
    wire to the "positive" pin of the DC power plug, and then touch it to
    the + side of the alkaline cell. If the "charge" indicator on the MP3
    player comes on and stays on, then you need a 1.5 V adapter.

    If the "charge" indicator doesn't stay on, then use more tape and wire
    to put a second alkaline cell in series with the first one, - to + .
    Touch the wire from the DC power plug to the + side of the second
    alkaline cell; if the "charge" indicator comes on and stays on, then
    you need a 3 V adapter.

    If you can't get any response by the time you get to 6 V (4 alkaline
    cells in series), don't go up any further.

    If you find a voltage that works, use the multimeter to measure the
    current the MP3 player is drawing when charging the battery, and select
    an adapter with a little more (not a lot more) current than that. Or,
    divide 0.38 by the voltage you found to get an estimate - if you found
    that 3 V worked, 0.38 W / 0.38 V = 0.13 A. Select an adapter with at
    least the measured or estimated current, up to maybe twice the measured
    or estimated current. A thrift store can be a good place to find an
    adapter, if you don't mind shopping around a little.

    Cut off the existing plug on the adapter (unless it happens to match)
    and use the multimeter to figure out its polarity. Wire the adapter
    to your new plug and enjoy.

    Standard disclaimers apply: I don't get money or other consideration
    from any companies mentioned.

    Also, please be sure to wear appropriate personal protective equipment
    while doing all this. You probably don't need arc flash protection at
    this power level, but you do need gloves, safety goggles, hand rails,
    and if your workspace is near the stairs, a properly-tethered fall
    harness. Someone with first aid training needs to be nearby, and it
    helps if there is an AED available. :)

    Matt Roberds
  3. Probably more than 1.2 V. More below.
    [snip a whole bunch of good advice}
    If the "charge" indicator on the MP3 player comes on and stays on, then youneed a 1.5 V adapter.
    [more snippage]
    A thrift store can be a good place to find an adapter, if you don't mind shopping around a little.
    [snip even more]
    You probably don't need arc flash protection at this power level,...
    [snip again]
    :) Matt Roberds
    I've seen some arc flash videos, and they are quite dramatic. I think I canavoid that fate by being careful.

    I have several shoe boxes full of wall warts. It was a thrift store that came up with the computer cable with the odd Rio plug on one end. There are two thrift stores nearby with bins full of cheap, as in $1 or $2, wall warts.. At yard sales, they usually fetch less than that. Finding one with the right current and the right voltage and the right polarity and the right sizeconnector is the trick.

    I've been thinking that 3 volts was about right.

    Thanks for the help.
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