BeagleBoard XM won't boot from 5V supply

I received a new BeagleBoard Xm today and successfully powered it up using an external 5V supply and the provided SD card with the serial port connected. So far, so good. I wanted to try an Ubuntu image so after unplugging the power I replaced the SD card with the new one I’d copied the image to (using Win32DiskImager). I plugged the 5V power in and all I get is D13 lit red and D14 green. No messages on the console and no sign of any SD card access. Checking Google I found that D13 suggests the power is outside limits. I checked the PSU with a voltmeter (unloaded, obviously) and got 5.26V, which is a tad high. I tried another supply which gave 5.16V with the same result and then a third PSU set to 4.5V which showed 4.67V on the meter. Same result. Surely the D13 is not correctly reflecting a voltage which is above limits? I then tried booting from USB power and the board boots quite happily from the provided SD card, although D13 is still shining brightly. Is this simply a case of returning the board as faulty, or is there some magic incantation I’m not aware of?

Make sure your power supply is grounded to earth ground. Sometime a bad ground will cause the protection circuit to trip. Make sure the PC and the board supply connect to the same powerstrip. You can also connect the serial cable or the DVI-D and that can help in some cases to complete the ground connection.

Gerald

Thanks for the response. Tried it with both the HDMI and the serial ports attached and same result. The power supplies that I’m using don’t have an earth (they’re the variable voltage style and connect to the mains with a figure-8 cable). The fact that D13 is on when powering from USB makes me think the board is screwed so I will send it back.

Regards,

Simon.

http://beagleboard.org/support/rma

Gerald