[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly - eviltoast

EDIT: Thanks everyone for you help, that has been very instructive. I think I just have a very poor quality cable adapter. Given that Blueretro is mostly an opensource DIY project, I’ll make a cable adapter myself instead of trying to fix what would obviously not function properly.

Hi everyone,

First of all let me say that I’m a total noob in electronics (I really only know the basics) and I’m facing an issue that I really don’t know how to tackle.

I have bought a Blueretro NES adapter on Aliexpress (this one) and it does behave erratically when powered by the console alone (Bluetooth not working, LED indicator down, random outputs to the console).

When I’m powering via USB, everything function properly.

So I guessed that I might have a voltage issue on the NES side. I tested mine and make a few friend test theirs (5 in total including mine) and the result is still the same: the controller ports outputs between 4.6 and 4.8V instead of 5V.

The Blueretro itself apparently uses an AMS1117 (picture here) which, from my understanding, is stepping down 5V to 3.3V (wild guess, I don’t really know what it does, just quickly read the datasheet).

So, sorry for the long intro, here are my questions:

  • Is it wise to try to step up the voltage from the NES to the Blueretro from 4.6V to 5V? How would it be possible? Is it even possible?
  • Given that the Blueretro is taking 3.3V apparently, is it possible to step down from 4.6V to 3.3V instead? Is it wiser than stepping up?

Thanks in advance and sorry for the long post :)

  • Gurfaild@feddit.deEnglish
    2·
    5 months ago

    If the controller port is connected to the same +5V rail as the CPU, wouldn’t the NES crash if it only got 4.6V or less?

    If only the BlueRetro is affected, maybe something behaves like a resistor in series with it, for example a broken solder joint in the adapter or at the connector on the NES

    • hylobates@jlai.luOPEnglish
      1·
      5 months ago

      Only Blueretro is affected. Maybe the Blueretro NES adapter cable has just poor quality components. The other cable adapters I have for other consoles work fine, including the SNES which also operates in 5V.

      • Dave.@aussie.zoneEnglish
        2·
        5 months ago

        Could be. The way the voltage sags at the end of the cable with the blueretro connected suggests that someone skimped on copper in the wires.

        If you can figure out a way to measure the voltage at the port with the cable attached and powering the blueretro, do that. If it is mostly the same whether the blueretro is connected or not, yep, it’s the cable.

        • hylobates@jlai.luOPEnglish
          2·
          5 months ago

          I managed to do that (not an easy fit but I think I’ve achieved the measurement properly) and you’re right: the cable itself it probably of very poor quality. Given that Blueretro is mostly a DIY project I think I’ll make the cable adapter myself instead of trying to fix what is obviously not fixable.

          Thanks for the help!