OSSC 1.6 – Plugged in wrong PSU

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  • October 7, 2021 at 10:49 PM #49647
    oddz
    Participant

      Hello,

      I accidently plugged in the wrong PSU adapter in my OSSC (i was drunk), it didn’t turn on anymore. I checked my fuses and realized the F1 burnt. I had no replacement component so I bridged it. F2 and D5 show continuity though. Now my OSSC does turn on but I have no sync, no image shows up. I remember there used to be a black and white screen with squares when I turned the thing on, I don’t have that anymore. Any idea which components to check/replace ?

      October 9, 2021 at 5:33 PM #49669
      Morpheus_79
      Participant

        Had the wrong PSU reversed polarity or a higher voltage? Did you check all the voltage regulators for shorts? Does the LCD of your OSSC works fine and shows no ‘Init Error'(?) – like described here:

        OSSC Init Error -2. Need replacement

        October 9, 2021 at 7:41 PM #49671
        oddz
        Participant

          Thanks for you reply,

          I plugged in a 12V PSU. The LCD works just fine and shows no error, it reacts well to the remote controller too, channels, etc…
          Not sure how to check properly if voltage regulators are shorted, they have 5 pins. I place the red of my multimeter on one pin and the black on ground, if I have continuity the component is dead, right ?

          October 9, 2021 at 11:28 PM #49673
          Morpheus_79
          Participant

            From here:

            https://github.com/marqs85/ossc_pcb/blob/v1.6/assembly/assembly_tips.txt

            -on bottom side, there are 8 small regulators in SOT-23-5 packages (U6, U7 etc.). Verify with a continuity meter that only the middle pin on the side with 3 legs is connected to ground
            -on top side, there is one larger regulator (U5) behind the display. Verify that only the middle pin (on the side with 3 pins) and the heatsink pin are connected to GND

            October 11, 2021 at 9:06 AM #49689
            oddz
            Participant

              Ok, so after tests, U6 and U16 have one pin shorted to ground on the 2 pins side, and U5 has 2 pins shorted to ground on the 3 pins side, the middle one is not shorted to ground which is weird, no ?

              October 11, 2021 at 7:39 PM #49703
              marqs
              Participant

                Sounds like there’s something wrong in the measurement or parts are different – is the board DIY, bought from VGP or elsewhere? The symptoms indicate U3 may have been damaged which has been the case with some other people.

                October 12, 2021 at 7:31 AM #49718
                oddz
                Participant

                  I don’t know about the board, I bought it second hand on Ebay.

                  I don’t think my measurements are wrong, I checked again.
                  I have ground on the middle pin (on the 3 pins side) on all regulators except on U5. U6 and U16 have one pin shorted to ground on the 2 pins side, and U5 has 2 pins shorted to ground on the 3 pins side. U3 seems ok.

                  October 12, 2021 at 10:28 PM #49727
                  marqs
                  Participant

                    U6 and U16 are either using a different part (that has additional ground pin on the other side) or their output is shorted to ground. You should measure their output voltages. Since FPGA and character LCD are working, U5 should be fine.

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