Memory stick faulty.

Discussion in 'General Electronics Chat' started by haamer, Apr 15, 2011.

  1. haamer

    Thread Starter New Member

    Sep 20, 2010
    I have USB drive 32G, but it had fallen in snow and stayd in there for few hours, until I had discovered its missing and then search and found.
    But it didnt work, though I didnt try to run it until I had dryed it for 12 hours.

    Still no luck and I have opened it and checked for probable causes, but there was none. At first I suspect quartz 12 MHz, but I checked it with my osc. and there on one end is a 12 MHz, BUT it is almoust perfect sine wave and p-p is around 3 volts. Does anyone know, is this normal?

    So I assumed, that quarz is running and checked these USB inputs, there are two data lines, probably clock and data I suspect, I m not familiare with USB. So there is no activity in there, and I checked two resistor-like objects on both of these data lines path, and there seems to be no conductivity. Markings are RM1 and RM2, as can be seen from photo.
    Does anyone know, what is excactly their nature? And can I bypass them by solder. I suspect that they are some barriers to protect for static or something.
    remdisk32g faulty.JPG

    Any help is welcome.
  2. tom66

    Senior Member

    May 9, 2009
    Those resistors are for ESD protection as you guessed. Ideally, replace them with 47 or 100 ohm resistors. But be careful, the board is likely 4 layer. Heat it with care and do not damage an internal layer.

    3Vp-p sounds right for the xtal. But if that is not working, the USB interface will not work...
    haamer likes this.
  3. SgtWookie


    Jul 17, 2007
    You may have simply tried to power it up too soon.

    You might take some uncooked rice, put it in a zipper-type plastic bag with the USB stick for a couple of days. The uncooked rice acts as a dessicant, and draws the remaining moisture out from under IC's.
    DumboFixer likes this.
  4. DumboFixer

    Active Member

    Feb 10, 2009
    Great tip - I'll have to remember that for the next time my Mrs soaks her mobile/cell phone