Accidentally plugged 12V – Burned?

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  • March 17, 2019 at 1:29 AM #25604
    Squeeze
    Participant

      I bought this amazing little machine a few months ago and it has worked prefect…until today :/

      Accidentally i connected 12v power (i have several DC adapters with the same plug and one of then has 12V output).
      The display started to flash and in matter of seconds i powered it down. I pluged in the correct adapter (5V), but the OSSC is totally dead.

      I opened it to check if there was any obvious faulty and I saw a suspicious area:

      OSSC Burned – Overview
      Check the area around the red circle lays my suspicion….

      OSSC Burned – Close up
      I don’t know what this is, but it might be flux from the manufacturing….or something has went quite hot here.

      OSSC Burned – Cleaned
      I cleaned up the mess with isopropanol.
      It look really nice and i’m almost about to hesitate…..but i took a couple more photos with better lighting och focus:

      OSSC Burned – Cleaned, better lighting

      If it’s just the capacitor (C93) that have been burned, what values should i look for?

      March 17, 2019 at 5:44 AM #25607
      Morpheus_79
      Participant

        EDIT: Just forgot -> you should check first if the F1 fuse isn’t blown…

        C93 & C31 are both 10µF capacitors. C93 could be broken. But afaik they seem to work as decoupling capacitors – so even if one of them (or both) are broken you should still see the unit powering up. It’s more likely the U5 regulator you’ve fried, since it’s rated for a maximum input voltage of around 6-6.5V… so you should measure if only the middle and the heatsink pin are connected to ground and if it outputs 3.3V.

        U5 is a bit tricky to desolder (since the display is nearby) but it is an inexpensive part to replace:

        https://www.mouser.de/ProductDetail/621-AP7361C-33E-13

        After replacing it you should make sure all the 8 smaller regulators (U6, U7 etc.) aren’t fried and (therefore) shorted to ground too before powering up the OSSC again.

        January 22, 2020 at 6:09 PM #34751
        Anonymous

          Hi,
          I burned the F1 fuse, with a 12v power supply (there is a mistake).

          January 23, 2020 at 1:59 PM #34779
          Anonymous

            hi,
            Can I use this : ANALOG DEVICES LDO REG, 1A, Precision 3.3V, SOT223 ADP3338AKCZ-3.3RL7 for U5 ?

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