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 ?
Hi François,
I’m having the same problem, but my Pixhawk suffered no accident, just stopped working serial ports 2, 3 and 4 after a firmware update.
You could solve your problem?
BR,
I had a look at the schematics of the pixhawk, they will allow me to localize the faulty component. In your case, maybe you can try to downgrade the firmware first ? Do you have a multimeter to check voltages/continuities ?
If it’s a hardware issue, I’m afraid it comes from a CMS, which is really difficult to replace. But I have two ideas of workarounds which will likely work well.
[quote=“gutomec”]Hi François,
I’m having the same problem, but my Pixhawk suffered no accident, just stopped working serial ports 2, 3 and 4 after a firmware update.
You could solve your problem?
BR,
Luiz.[/quote]
Hi friend, have you solved your problem?? I have the same, but it is my first pixhawk. I have low/no voltage in SERIAL 4/5, GPS, I2C, TELEM2. Only TELEM1 is working.
Well, I found something which is more a workaround than a perfect solution.
Looking at the pixhawk schematics, all the peripherals you mentioned are powered by the same power line “VDD_5V_PERIPH” (sheet 2/12, SERIAL2 (telem2), SERIAL3 (GPS), SERIAL4). Sheet 4/12, you can see that SPI, I2C1(compass), PRESSURE (for external sensor, noted ADC 6.6V on pixhawk case) and AUX ADC (noted ADC 3.3V and CAN), are also powered by “VDD_5V_PERIPH”. I suppose that all those component are unpowered as well.
Looking at sheet 6/12, the main input power “VDD_5V_IN” is split into multiple power circuits. As Telem1 and all sensors are working, and all components on “VDD_5V_PERIPH” are not powered, the defective component likely is : U602, BQ24315, sheet 6/12. This is an overvoltage and overcurrent protection IC, circled [color=#FF0000]in red[/color] in the attached photo. The pin 1 is the input (VDD_5V_IN) and the pin 8 is the ouput (VDD_5V_PERIPH).
What I did is to test all pins of this IC : all the inputs are OK, but the pin 8 is not powered, meaning that this tiny component is broken. As this is a very small SMD component, I don’t have the skills to replace it.
Finally my workaround was to bypass this overvoltage/overcurrent IC with a little electric wire, connecting pin 1 to pin 8. But you don’t have to connect the very little pins in place (which would be very difficult), as they are both connected to large capacitors which are easy to solder. I colored [color=#0000FF]in blue[/color] the two capacitor extremities you have to solder.
Doing like this will work well, but you loose the overcurrent and overvoltage protection on this power line.
Well, I found something which is more a workaround than a perfect solution.
Looking at the pixhawk schematics, all the peripherals you mentioned are powered by the same power line “VDD_5V_PERIPH” (sheet 2/12, SERIAL2 (telem2), SERIAL3 (GPS), SERIAL4). Sheet 4/12, you can see that SPI, I2C1(compass), PRESSURE (for external sensor, noted ADC 6.6V on pixhawk case) and AUX ADC (noted ADC 3.3V and CAN), are also powered by “VDD_5V_PERIPH”. I suppose that all those component are unpowered as well.
Looking at sheet 6/12, the main input power “VDD_5V_IN” is split into multiple power circuits. As Telem1 and all sensors are working, and all components on “VDD_5V_PERIPH” are not powered, the defective component likely is : U602, BQ24315, sheet 6/12. This is an overvoltage and overcurrent protection IC, circled [color=#FF0000]in red[/color] in the attached photo. The pin 1 is the input (VDD_5V_IN) and the pin 8 is the ouput (VDD_5V_PERIPH).
What I did is to test all pins of this IC : all the inputs are OK, but the pin 8 is not powered, meaning that this tiny component is broken. As this is a very small SMD component, I don’t have the skills to replace it.
Finally my workaround was to bypass this overvoltage/overcurrent IC with a little electric wire, connecting pin 1 to pin 8. But you don’t have to connect the very little pins in place (which would be very difficult), as they are both connected to large capacitors which are easy to solder. I colored [color=#0000FF]in blue[/color] the two capacitor extremities you have to solder.
Doing like this will work well, but you loose the overcurrent and overvoltage protection on this power line.
Hope this will help, don’t hesitate to ask more.[/quote]
Hi friends, thank you for this workaround.
Instead I bought it 6 months ago and only last week I had time to assemble my kit, I contacted the store who sold me and they told me they will replace it for me, otherwise I’ll do your workaround.
i have same issue missing power to serial 4/5 i did found out that if i start the system without any peripherals connected i do get the 5v and if i now connect the GPS it will power on and the 5v stays, but when i reconnect the power it will lose the 5v, so i guess the issue is only at start-up, any chance to fix without bypassing the O.V O.C protection?
Hi,
I already tried to power the board without peripherals and then measure the voltage but it gives something near 0V. It looks like there is an hardware issue on pixhawks, and this is not the first one
You can try your seller’s warranty, otherwise I recommend to read the BQ24315 datasheet and check all the pins first.
Then I have to say that my bypass solution works with no issue for 15 flights.
