This is a discussion re the bad Accel, Gyro and Baro values that we're seeing with ArduCopter-3.1. The increase in the SPI bus speed from 500khz to 8Mhz has exposed a hardware problem on some boards. That hardware problem is that the 3.3V regulator has been blown so all sensors are running at 5V instead of the intended 3.3V.
How have these regulators been burnt out?
- Attaching a radio receiver or MinimOSD to the APM while the APM is only powered through the USB (see video below)
- Some clone boards seem to come from the factory with blown regulators. 3DR boards might also come with blown regulators although they do a specific check of the regulator as part of the regular QA process.
- It is not (as far as we know) actually caused by the AC3.1 software itself, it just exposes the problem. You could prove this to yourself by checking the 3.3V regulator (see video above) before and after the upgrade.
How can we fix the regulator?
Option #1: If it's a new board (so that it's less likely you burned it out yourself) you could report the problem to the retailer that sold you the board and ask for an replacement. If it's 3DR it's called an "RMA".
Option #2: if you're handy with a soldering iron you can replace the regulator yourself. On the APM2.5.2 (and higher) boards it's not that difficult. On the APM2.5 it's far more difficult.
For APM2.5.2 : TPS79133DBVR
For APM 2.5: MIC5219-3.3YML TR
How can I stop it from happening again?
Do not connect any devices such as a radio receiver, MinimOSD, GPS, etc while the APM is powered especially while powered only through the USB cable.
Attaching a 100uF capacitor across any of the APM's radio input's 5V and GND pins will stop the regulator from being blown by plugging in a receiver. video here!
There are very few reports of regulators being blown twice and no reports of it ever failing in flight.
Below are some graphs of the types of values that we are seeing on these boards.
Replies
No, that's not correct. You won't fry your board by simply connecting the USB and battery while JP1 is installed.
agreed, it depends where if you connect the cable wrong and voltage of usb or the UBEC is higher that 5.7v. Other than that we're trying to figure out what could have caused it and why amu6000 is acting weird when voltage reach 5v
agreed
http://copter.ardupilot.com/wiki/common-apm25-and-26-overview/#Powe...
This was how i solved my 3.3V regulator issue without having to solder the smt mounted TPS79133..
http://flight.farbird.com/2014/02/repair-blown-33v-regulator-on-ard...
hope this helps
Ok I am relatively new in multicopters but maybe this can help you
3DR Original APM 2.0 whit on-board GPS V2.4.1 , firmware version AR 2.43 AP 2.76 AC 3.0.1 everything is ok more than 50 flights
After this I am Installing new firmware AC 3.1.2 the latest, 1 flight everyting seams ok but on second flight I cant arm the APM
And its showing PreArm:ACRO_BAL_ROLL/PICH
I make some search and found that since AC 3.0.1 (not including AC 3.0.1)this parameter on Roll and Pich after you upload new firmware is 1 not 0 like before, so I switch this form 1 to 0 on AC 3.1.2 and I lost the error message but I noticed something really strange !!!
APM conected on USB only the board nothing else attached running on AC 3.1; AC 3.1.1; AC 3.1.2 (tried an all 3 firmwares). See picture 1 on this parameter (battery_voltage) voltage was constantly upraising from 1.2 up to 9.0 and felt directly back to 1.2 variegating like this constantly !!!
But APM running on same conditions only with firmware AC 3.0.1 and AC 2.9.1b this parameter is rock solid and is showing value of 11.025
I don't understand this ! with firmware changing, the battery_voltage parameter is changing, and APM plugged in only on USB ! some advise please?
Picture 1
Picture 2
Thanks and sorry for bad English ;)
Sasho, it seems you are in the wrong forum. This place is to discuss what is causing 3.3v regulator failures. It primarily focuses on hardware issues. Yours seems software related...
I fixed mine using replacing the regulator but mean while it was down i ordered a another APM. Then i noticed something. The magnetometer connector plug on my old apm is soldered wrong way so thats why i blew my regulator. First i thought it was the cable that was crimped wrong but i was wrong. Its the APM connector.
Other than that i noticed something else. New APM is clearly smoother than my old. My quad used to turn to left while its descending now it does not do that on my new APM and really stable using same config file.
Hans, are you sure about that?
It is the 4-pin I2C connector you are talking about right?
I want to make sure about this because I am about to switch to external regulator on my APM 2.5. I will be using that I2C connector...
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