B7 no longer responds to DC power jack

Sorry if this is a repeat, but I could not find a similar issue
despite extensive searching.

I was running the Angstrom distribution on a revB7 Beagle Board using
a powered hub, providing power to the board with a USB-to-barrel
connector. It was working fine until I shut down Angstrom. Shutdown
was normal, and when it got down to one LED I disconnected power from
the board, as I have done dozens of times. Plugging the barrel
connector back in now has no effect---no boot, no LEDs. The barrel
plug shows 5V just as it always has. The board boots fine using OTG,
but I am trying to use it in host mode.

Did I somehow flip a switch by using shutdown, and if so, how do I
flip it back? Worse, did I brick the power connector on the board
somehow? That seems unlikely since it powers up fine with a USB
cable. Any ideas would be helpful.

thanks

There is no “Switch” to flip. What you describe does not make a lot of sense. The DC power connects to the same LDO as the USB power does via the TPS2141. I can’t really think of an explanation for what you are seeing.

Gerald

Thanks---at least I'm not going totally crazy then. It literally
powers up fine with the USB connector, but does nothing with the DC
power jack.

All I can guess is that the power jack itself has somehow come
physically disconnected. I'll get out a loupe and take a look,
although it looks normal with the naked eye.

Could the outside pressure tab have been sprung somehow?

Gerald

following up---it looks like something is wrong with the jack
itself.

when the plug is NOT plugged in:
- continuity OK from the center post to the back of the jack
- continuity OK from the barrel catch inside the jack to the side of
the jack

when the plug is plugged in:
- continuity OK from the center post to the back of the jack
- NO continuity from barrel of plug to side of the jack

Nothing is apparently amiss, but obviously something is broken
inside. Can this jack be replaced in the field? I'd rather not go
through an RMA, I'm in testing mode. Might try to find a matching
jack and solder it in.

Note to the unwary---plug the thing into a regular switch when doing
multiple power events. Don't use the power jack any more than
necessary.

Final reply---the loupe shows all. The inside of the jack has a
pressure tab that is compressed when the plug is inserted. This tab
broke off at its innermost point, but still springs back up when
pressure is released. This explains why continuity was present
without a plug but not with a plug.

So... possible fixes:
- replace the jack
- solder on a second jack
- resign myself to just using OTG (can't do)

Hope this helps someone in a similar predicament someday!

Jeff

You can replace the jack. The part number is on the BOM and you can order it from DigiKey. It sounds like maybe you applied some upward pressure when you unplugged it. This can happen if your outside diameter of the plug is not exactly the right size. I have only seen one other instance of this happening.

Gerald

You can replace the jack. The part number is on the BOM and you can order it
from DigiKey.

Great, thanks! Although now my chances of expensing a rev C board are
shot until I break something else.

It sounds like maybe you applied some upward pressure when you
unplugged it. This can happen if your outside diameter of the plug is not
exactly the right size. I have only seen one other instance of this
happening.

Interesting. This is the USB-to-barrel connector plug sold through
Special Computing---it seems like it fits exactly right. My guess is
that I did just as you said and put upward pressure on it while
unplugging. I may put an inline switch into the wire, as I bet I
could fatigue that little metal part with lots of power events.

This is a good reminder that not all "moving" parts in a computer are
electrically driven, and that anything that moves can be subject to
mishandling or fatigue.

Thanks again for the advice