Messed up upgrade 1,6 version – what value is R35?

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  • August 1, 2025 at 2:38 PM #66721
    JohnFante
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      I am trying to upgrade an old 1.6 OSSC to be able to run the latest firmwares. At first I had success but then the wire fell of the IC and things went sideways from there. Managed to remove and loose R36 (besides R35) under my attempts to salvage things. As far as I can see the top pad also fell of R35 and the IC legs got soldered together. Complete F…Up, so it has been resting on a shelf for a year. But now it is time to try to resurrect the old girl …

      Firstly: What value is R36 and what are the specs if I need to buy the part online.

      Secondly: Is the top pad on R35 needed or can I just solder the wire to the bottom pad and go from there?

      Thirdly: What is the best way to clean up the mess on the IC?

      Fourthly: What is the easiest way to connect the heatsink to the IC? I have tried mixing a special kind of glue intended for this but that did not work so I am looking for some kind of tape.

      Fifth: Does anyone – except VideoGamePerfection that only takes their own OSSC’s – do upgrades/cleanups? Mine is a Chinese model as far as I can see. Used to work perfectly before I got too ambitious.

      Thank you in advance!

      August 6, 2025 at 2:38 AM #66754
      Morpheus_79
      Participant

        What value is R36 and what are the specs if I need to buy the part online.

        According to the official BOM R35 and R36 are 330 ohm resistors:

        https://github.com/marqs85/ossc_pcb/tree/v1.6/bom

        They are both current limiting resistors -> one for each LED:

        https://www.build-electronic-circuits.com/current-limiting-resistor/

         

        Is the top pad on R35 needed or can I just solder the wire to the bottom pad and go from there?

        The wire needs to be soldered to the pad connected to the Cyclone IV FPGA (U2). The other pad is connected to the LED. I don’t know if on your Chinese OSSC the top or bottom pad connects to the FPGA -> but the wire HAS TO BE connected to the correct pad… otherwise the mod won’t work!

         

        What is the best way to clean up the mess on the IC?

        Solder wick???

         

        What is the easiest way to connect the heatsink to the IC?

        There’s thermally conductive (epoxy) glue for (permanently) mounting a heat sink onto an integrated circuit. If you want a reversible solution: there’s also thermally conductive adhesive tape. Keep in mind: you need thermally conductive stuff -> regular glue and regular adhesive tape WON’T WORK!!!

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