I need to use the 5v rails for about 300-400 miliamps so after doing a bunch of reading I found out that I could pull this from the 5v rail IF I used an external power adapter.
I found one on amazon and got it here today. Its 5v @3 amps. I check it out and it looks to be about at 5.25V. Here is a video of what is happening.
It looks like it turns on… the user leds light up then everything just fails. I am not sure what the issue is. I have tried 2 different BBB’s and both exhibit the exact same behavior.
Put an oscilloscope on the power input while you are doing all this.
If the Voltage goes above 5.5 or below 4.5 on a transient basis, the BBB on board power supply will shut down.
I am suspecting that your power supply does not have good transient regulation.
5.25V is a little high and in reality it may be even higher on power up. The spec is 5V. I suggest you try and meet the specification and get a good power supply.
Another possibility is that while the supply is rated at 3A, it may have a surge limiting function based on the product it was designed for. It could be that as the board powers up and the current increases, it increases to fast causing the power supply to shut down. I cannot say that is the case or not based on a video.
Also, based on the video you need t plug in the power jack., not wiggle it in. Just plug in in firmly.
Voltage has to be too high, or not high enough. I’d assume too high as you’ve already stated the power supply is 5.25v. The reason why I say it has to be this, is that the power LED goes out nearly instantly.
try powering the board through an USB cable, to make sure that it is nothing related to the hw or sw on the board.
If positive then try with a power supply that match the minimal requirements.
Thanks for the help. It turns out I bought 2x of these crappy adapters on Amazon ( i could get in 1 day ). I ended up checking out the other adapter. It was pumping out 13v that should be 5v! I am lucky I started with the other one. I could have hooked up the scope to check this out but I have decided you guys are most likely 100% correct. I am not even going to risk the “good” 5.25v one on my bone. I ordered some quality adapters from adafruit.
Thanks for the quick reply guys!