Dead AQ board

[SuperSharpShooter]

I've just received a replacement AQ board, done all the calibrations and got it flying ok.

I plugged it in this morning and the LEDs turned on on the arms as normal, but then after about 10 seconds they went out and the ESCs started beeping slowly. At this point I noticed all of the lights on the AQ board has gone out. Reconnecting the power to the board, and the lights all stay off.

Please help!

[SuperSharpShooter]

This is the very short log produced before the lights went out. It seems that once the alexmos board came to life and the camera stabilised, that the AQ board stopped. From the symptoms it sounds like a dead MCU.

The connections from the AQ board are:
PPM connection from my frsky receiver on pwm 14, which has a 100R resistor on the signal line.
3dr radio on the telemetry port which has 100R resistors on both signal lines. J3 is closed to power the radio.
Two signal wires running to a uln2803 which my 12V signalling LEDs are connected to.
Gimbal pitch and roll outputs from the AQ to the alexmos board (FCR and FCP inputs).
Tilt output from the AQ to the RXP input on the alexmos board.

[LPR]

Glenn

Sorry to here that your board's MCU had an untimely end. I have taken out two MCU and both were my fault. I'm not counting the board that somehow managed to get reversed voltage. It does not take a lot to blow a MCU. A little static of connecting wires while the MCU is running may cause a 7 volt spike in voltage and that's all it takes. I have soldered in two MCUs and they both worked so I think you can manage to replace them if you have good magnification. 10x stereo microscope is that I use.

Larry

[SuperSharpShooter]

Damn, yeah I will have to be more careful with everything in future. I thought I would be safe with the resistors on the rx and 3dr radio signal lines, but didn't have the ground lines connected for the signals to the alexmos board, or resistors on their signal lines. Would having resistors on these help or not? Also the rx cable passed within 1cm of an ESC power wire, so I'm not sure if it was the gimbal or the rx that did it. I'll connect all grounds to the accessories from now on and make sure the wires are better separated.

I take it it is dangerous because of potential voltage spikes to connect or switch any other accessory's power while the aq board is powered?

Thankfully Jussi is sorting me out.

[joebar.rc]

[SuperSharpShooter]

Just had one more question on this. Is it OK to connect a second battery to the PDB once the AQ board has been powered by the first lipo, or is that also risky for the MCU?

[JussiH]

The biggest current spike happens on powerup of the system when the caps on the ESC´s system charges up. When you connect the first lipo there will be usually be some sparking there because of the current inrush to the caps. So when you connect lipo 2 the system is already powered and it should not pose a problem.

Adhere to the recommandations about twisting/braiding current carrying wires and run individual ground wires on all signals, and keeping signals seperated from main power distribution.

[LPR]

Glenn

Connecting a parallel battery is no problem. I've used two batteries with no problem for a long time.
The MCU is sensitive to very small spikes in voltage to the signal inputs. Connecting RC receivers or a telemetry radio while the AQ is powered can be a problem. Having power wires not twisted can produce voltage spikes in signal wires. The ESCs signals wires should not be run next to untwisted power wires.

Larry

[SuperSharpShooter]

Alright got it, thanks.