Power puzzle: 5V drops to 4.5V

Discuss Yocto construction and related issues
  • I tried swapping a 6n139 for the 6n138, but my 5V still drops to 4.5V

    This really seems like a current/power draw issue -- could the LM2596 be failing and no longer supplying 3A, causing the voltage drop when the sequencer increases the current being pulled? Seems like a long shot but I am desperate for a solution...
  • pistrix wrote:I tried swapping a 6n139 for the 6n138, but my 5V still drops to 4.5V

    This really seems like a current/power draw issue -- could the LM2596 be failing and no longer supplying 3A, causing the voltage drop when the sequencer increases the current being pulled? Seems like a long shot but I am desperate for a solution...

    Have a look on 1N4004s and capacitors way on the IO board. Then it could be the LM2596.
    Best regards,
    e-licktronic
  • Thanks for the reply !

    The diodes and caps are all in correctly..I'm putting an order in for a replacement LM2596T today, hope it does the trick
  • well the new LM2596 didn't change anything

    but i figured it out! after working backwards thru the 5V line on both of my IO boards, i found that the 680uf capacitor on the problem IO board was knocking the input voltage going to the LM2596 down to 8.3V...and it should be about 22V..i replaced it and finally i am back to steady 5V and correct working sequencer again...hurray!