hiya!

I got a cheap LED strip with PSU, controller, and IR remote. I didn’t look at it too much, figured it would be easy to stick it under my kitchen cabinets.

however, this thing blinks and fades and whatnot and I’m supposed to switch it over to constant light by repeatedly pressing the remote, which a) works shitty and also b) don’t wanna do that. I just want to plug it into power and it lights up and that’s the end of our interaction.

so, I opened up the PSU/controller and I’d like to locate the spots that give me +12V and GND and I can bypass the whole blinky fadey mess.

it’s a single-sided PCB. the top three wires on the right are for the IR receiver, ignore 'em. the bottom 4 are R, G, B, 12 V, respectively. I’m shorting RGB as it’s a white-only strip.

can you hazard a guess where I’m most likely to succeed?

  • CameronDevEnglish
    3·
    2 days ago

    Bottom leg of the transistor to the left of the signal wires would be my guess for ground, do you have a multimeter to check?

    Looks like a large ground plane to the left of the transistors, so you might be able to scratch away the coating and solder directly to it.

    • dingdongitsabear@lemmy.mlOPEnglish
      2·
      2 days ago

      I do, and when I check the 12 V wire, it fluctuates between 12 and 5 V (that’s the blink/fade thing) so I need 12 V before it gets mangled. where am I most likely to get it from?

      edit: how do I check if the plane is ground with a multimeter?

      • CameronDevEnglish
        1·
        2 days ago

        You can’t check for ground specifically, you just check for a 12v difference between two points, and call those +12 and GND.

        Feels odd that they are pulsing the entire 12v line, but I’m guessing it was something cheap.

        The bottom leg of the transistor definitely looks like GND to me, so I think you just want to probe around (carefully!!) to find the stable 12V. I would avoid the entire live side, and for safety, might be worth taping it up.

        If you cant find a stable 12v, you may want to get a cheap 12v power supply? Old laptops are often 12v, power too chargers as well are often 12v.

        • dingdongitsabear@lemmy.mlOPEnglish
          2·
          2 days ago

          measuring difference between ground plane and the various points didn’t give me a stable voltage. the black thingy leading to the 12 V line is a SS210 (search says that’s a schottky diode) and on its output the mentioned fluctuation is happening. on its input there’s some very low voltage happening that’s also fluctuating, like sub 1V (got a shitty multimeter).

          if I’m understanding this correctly, then this thing boosts the voltage but the fluctuation is happening somewhere else. in other words, there is no 12 V source on this board. or?

          • CameronDevEnglish
            2·
            2 days ago

            Maybe you can trace that low voltage fluctuating line back to one of the ICs?, and work put how to disable that IC?

            Or, use the remote to output solid white, and find the voltage on that line, and then try find that voltage somewhere else and short the two?

            I’m running out of ideas though, I suspect buying a cheapo power supply might be easier :/