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Belkin F5C520 UPS...

Discussion in 'Electronic Repair' started by lj_robins, Sep 2, 2007.

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  1. lj_robins

    lj_robins Guest

    Hi,

    I am looking for a schematic for a Belkin F5C520 UPS.

    In case you are wondering and/or can help, output voltage for charging
    the battery is only coming out at 2.4 volts with the battery unhooked
    from the circuit.

    Nothing appears to be fried on the circuit board, no bulging capacitors,
    etc. It has what appears to be an LM317 based voltage regulator system,
    this is more is less where my trouble shooting is going to start.

    So far I have figured out that the 317 has 23 volts on the input pin,
    ADJ and OUT have approx 2.1 volts on them. There are what appears to be
    three little tiny resistors attached to the ADJ pin, and a 2N2222A
    transistor is somehow hooked it the ADJ as well, it tests fine.

    Not sure where to go from here without a schematic.




    Thanks,

    -Landon
     
  2. I don't like servicing without a schematic, either. But considering that the
    LM317 and a 2N2222A are a lot cheaper than your time, why don't you just
    replace them and see that happens?

    As the output of the LM317 is well below what it ought to be, the odds are
    pretty good it's defective.
     
  3. : I am looking for a schematic for a Belkin F5C520 UPS.

    : In case you are wondering and/or can help, output voltage for charging
    : the battery is only coming out at 2.4 volts with the battery unhooked
    : from the circuit.


    Finding a schematic is doubtful.

    Don't assume that 2.4v reading without the batteries is incorrect. Most
    UPS's don't use a constant charge voltage, it's pulsed on/off on a duty
    cycle depending on the current battery charge level.

    Unless you tried a fresh set of batteries, it's not really worth the time to
    look at the circuitry.

    That is the rub, likely the cost of them is going to be 50-75% of the
    replacement value of the ups to begin with.

    If you really think it has something to do with a LM317 and 2N2222's, those
    are nickel/dime parts (if that much) but I really doubt they have anything
    to do with the charging circuit.

    Belkin already discontinued that model, they have larger capacity ones for
    under $100. Most places are selling the battery for the 520 at $41-$49 plus
    shipping.

    It's just not worth it.

    -bruce
     
  4. lj_robins

    lj_robins Guest

    Thanks for the reply, you are correct it will not put out 14 volts
    without the battery being hooked up to it, my other two UPS'es would put
    out voltage whether or not the battery was hooked up so I thought this
    one would act the same.

    This USP is discontinued as you already stated, even the owner's manual
    posted online lists the software as Windows 95/98, the battery is
    available for $20 to $40 depending on where you go, there is a local
    place I get UPS batteries from I'm going to see how much they want for
    it when they are open and then I will decide what to do.

    I already told the owner that the UPS was going to be disposed of so I'm
    off the hook in that regard.


    Thanks again.

    -Landon
     
  5. Jerry G.

    Jerry G. Guest

    Firstly, Belkin like the rest of them, will not give out any schematics or
    service information.

    Before you tear in to the UPS, put on a new set of batteries! The chargers
    in these are a pulse charge system with a very sophisticated load sensing.
    If the battery is slightly out of spec for the charger, it will not charge
    the battery.

    I have some Belkin and APC UPS's in our place, and they all do the same
    effect that you are describing when the batteries have to be changed.

    --

    Jerry G.
    ======


    Hi,

    I am looking for a schematic for a Belkin F5C520 UPS.

    In case you are wondering and/or can help, output voltage for charging
    the battery is only coming out at 2.4 volts with the battery unhooked
    from the circuit.

    Nothing appears to be fried on the circuit board, no bulging capacitors,
    etc. It has what appears to be an LM317 based voltage regulator system,
    this is more is less where my trouble shooting is going to start.

    So far I have figured out that the 317 has 23 volts on the input pin,
    ADJ and OUT have approx 2.1 volts on them. There are what appears to be
    three little tiny resistors attached to the ADJ pin, and a 2N2222A
    transistor is somehow hooked it the ADJ as well, it tests fine.

    Not sure where to go from here without a schematic.




    Thanks,

    -Landon
     
  6. lj_robins

    lj_robins Guest

    Well, the battery was only $22 so I went ahead and bought it, could have
    bought it for $19 online but the shipping probably would have killed the
    $3 savings.

    But anyway... the unit has been charging for over 24 hours I have
    nothing plugged into the UPS outlets, right after I unplug the cord from
    the wall the voltage instantly drops from 122 VAC to 102 VAC and then it
    starts beeping and the voltage starts slowly dropping like it is
    supposed to. The user manual says that the output is supposed to be 120
    volts +/- 5%

    Also, if I disconnect the battery from the wires the battery is reading
    14 volts, and oddly the "On Battery" light is on even when it is
    charging. And finally, the output voltage now stays at 14 volts without
    the battery being plugged in.


    Any suggestions?
     
  7. lj_robins

    lj_robins Guest

    Well, this UPS has taken a turn for the weird...

    Found out that if I plug a PC into it (just the PC not the monitor) the
    output voltage will go up from 102 volts to 118 volts AC, which was
    close enough to 120 that I figured it would be ok. Then I plugged
    another PC into it and the voltage wavered for a moment or two then shot
    up to 130 volts.

    Sounds like a regulator has gone out, I'm almost wondering if this has
    anything to do with that LM317 I originally mentioned in my first posting.
     
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