Board not turning on -> polarity protection diode failed
I have the 8-bit Arduino compatible board.
When I turn the switch to PC or BLE there is no flashing blue LED. I have only used the battery pack that came with OpenBCI with 4 AA batteries. Multimeter shows output of each battery is 1.6 V, with the whole pack outputting little more than 6 V. The + and - terminals on the board also show a potential difference of a little more than 6 V, so I know the board is receiving power. Dongle is set to gp106 and has blue LED lit up, but board cannot communicate with it. Have tried resetting, but no response. I'm really confused.
When I turn the switch to PC or BLE there is no flashing blue LED. I have only used the battery pack that came with OpenBCI with 4 AA batteries. Multimeter shows output of each battery is 1.6 V, with the whole pack outputting little more than 6 V. The + and - terminals on the board also show a potential difference of a little more than 6 V, so I know the board is receiving power. Dongle is set to gp106 and has blue LED lit up, but board cannot communicate with it. Have tried resetting, but no response. I'm really confused.
Comments
Between the DVDD and GND I am getting only about 1.2 V. GND/AVSS is almost nothing (.01 V) and GND/AVDD is 0.16 V.
Pretty sure we have isolated the problem to the diode, which seems blown. When it is bypassed I get the LED response. I'm bewildered about what could've happened to the diode since there is no way to plug in the battery pack backwards and the batteries were always oriented correctly...
I've ordered a replacement smd diode - hopefully soldering that in will fix the issue.
I have the 8-bit board - if you do too, the diode series is CDSU400B. Here are the details on Mouser, which is where I ordered my replacement. Soldering it in fixed the problem.
If you have a different board, the diode specifications are given in the OpenBCI Docs in the Hardware section, somewhere within the PCB files.
CDBU0130L
V-in is 5.90V.
We are getting -2.5V between AGND and AVSS, +2.5V between AGND and AVDD, 3.3V between AGND and DVDD
I went successfully through the same diode replacement process.
Definitely the way to go. Just want to add that the way I burned the
diode was by plugging a 3.5V / 400mAh lipoly battery on the openbci
board version 3-8, which actually requires 6V -12V. So it looks like low
tension matters.