Need Help! Kflop boot voltage problem.

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Thread: Kflop boot voltage problem.

  1. #1
    Join Date
    Jul 2010

    Default Kflop boot voltage problem.

    I have an older Kflop (REV 1.1) that suddenly quit working. It will not boot from the USB power with the correct jumper in place. It also will not boot from 5.0 volts to the molex with the jumper positioned correctly.

    I can get it to boot by applying 5.5 volts on the molex connector, and it seems to work fine with the extra .5 volt. My main concern is that U2 gets too warm to keep your finger on it for any length of time.

    Does anyone know the specs on U2? I'm guessing it's a voltage regulator, but there are no markings.

    The Kflop draws about .9 amps at 5.5 volts. I'm not sure if this is in spec or not.

    Wondering if replacing U2 may fix it, or if there is something further downstream causing the heat on U2.

    The Kflop is out of the system with no other wires or board attached.


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  2. #2
    Gold Member TomKerekes's Avatar
    Join Date
    May 2006

    Default Re: Kflop boot voltage problem.

    Hi Todd,

    U2 is the 1.2V voltage regulator for the DSP Core. It normally runs warm but you should be able to leave your finger on it indefinitely.

    LD1117DT12 800ma IC LDO REGULATOR +1.2V DPAK ST LD1117DT12TR

    My guess would be something in the DSP is drawing excessive current.

    Did you try re-flashing the KFLOP Firmware with the "New Version" button. Unlikely to be a software problem but possibly worth a shot.

    KFLOP by itself with nothing connected should only draw around 0.3A.

    R5 acts sort of like a fuse to limit current draw from the 5V. Rev 1.1 used a 1ohm resistor. In later versions it was changed to a 0.1 ohm resistor because in cases of the 5V being low (ie 4.5V) and with large currents it would drop the voltage too much. Changing it to 0.1 ohms may allow it to then operate on 5V but wouldn't explain the large current.

    Rev 1.1 boards were shipped over 6 years ago. Maybe time for a new KFLOP



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Kflop boot voltage problem.

Kflop boot voltage problem.