Hi,
I had a crash last week with my quad and although it was not too violent and my (3DR) Pixhawk was mounted on a soft foam I think one part of the power circuit was broken. Now my 3DR Lea6H + Compass is weakly powered (led is weak, no GPS fix and compass bad health).
With my multimeter I measured low voltages (0.7V) on Telem2, Serial4/5, Serial3 (GPS), I2C, and others. Telem1, sensors, buzzer, switch are all working well. I had a look at the schematics, and it seems that "VDD_5V_PERIPH" no longer gives 5V power.
To check for bad solder I connected my multimeter to the Serial3 power output and tried to slightly press with my fingers on the components of my Pixhawk -> the voltage did not moved from 0.7V. On the schematics, sheet 6/12, I have seen that two components can be the source of this problem :
- an IC : U602 BQ24315,
- a capacitor : C618 100µ,
but I didn't manage to locate them on the Pixhawk PCB.
Can someone help me with this issue ?
As a workaround, what do you think about powering all those peripherals with a UBEC of an ESC ?
Many thanks,
François.
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Replies
Hi,powering the 3Dr Lea6H with a UBEC will work. But does the pressure sensor works? according to sheet 6 (in schematics) it's also powerd with VDD_5V_PERIPH?
chris
What you see page 6 is an analog "pressure" port (not the sensor), namely "ADC 6.6V" in the Pixhawk case. The pressure sensor (MS5611) is powered by VDD_3V3_SENSORS according to the "Sensors" sheet.
I had a look further and it looks like my BQ24315 is working well (5v output). So two options in my case :
- the BQ24315 is not well soldered,
- the circuit is almost broken somewhere,
- after the BQ24315, the power circuit systematically continues with two components (for almost each connector) : a filter in series (KNH16C104DA5TS) and a zener diode in parallel.
I think the third option is the most probable, maybe a shorted zener diode that drains the current. It would explain the 0.7v I measure, corresponding to the shorted zener. I will test them this evening.