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
Yes I read that, even the masochistic part. Failing sensors in flight with wrong horzion repot will - of course not lead to a crash - what a double lol.
Crashpilot,
I've already mentioned above that this thread is meant to help people with specific cases of blown regulators. Please keep on track.
Historically you've been a good contributor to this community, please come back.
Your previous statement was "orig 3DR board failed in flight"? The German forum said different - it was a clone board and no one claimed that the 3V reg failed (add: in flight)!! I think someone wrote he lost video pointing to a power failure? Or do you refer now to something else??
I didn't continue to read on there...
Well Randy, Detlef,
Hansaka says wrong wiring order on GPS harness blew his 3.3v reg.
I wonder if this action definitely blows the reg. I know the original GPS harness has an alignment tab on the connector but it is not impossible to force it the wrong way...
Did the hardware guys at 3DR check this scenario?
okay, i found this online http://www.ebay.com/itm/6DOF-MPU-6050-Accelerometer-Gyroscope-3-Axi...
I think this would replace my MPU and 3.3 regulator since it come with those two. My mission planner yelling at me saying gyro health is bad
Please remember, this thread is meant to inform and help people who are facing the 3.3V regulator issue. Let's keep it on topic and helpful.
On other hand... Do 3DR have manufacturing traceability systesm of the components that they use to build boards? I work for big hearing aids company and we have that system so if one component batch have fail then we can remove form the market boards/devices that are affected... If 3DR company don't track the parts is not ok... Maybe the issue laying on some batch of bad regulators and only some of the boards are affected... Is there any serial numbers? Time producing event we can track the failure? Like spectrum with their dsmx transmiters was have to be updated to use proper dsm2 Rx's or samsung with their galaxy s 3 phones with sudden death because of bad chip, it have to be some way to track the thing that's kill the reg or the bad reg batch itself... :/
Hi, my regulator is fine and showing 3.3v... How can i check what firmware i'm using? Can't find it in MP, i use wizard as i'm new to APM and in middle of assembling the quad... What is worry me that i don't have telemetry so i can make some couple of flights and suddenly make another one and my qaud will flip because of sensor on 5V? Now i'm afraid to use the APM :( Don't even get first flight... Why You cannot reproduce reg failure to know what to not do to blow it up? I read on Rcgropus that the failure can be reproduce when connecting Rx while the APM is power up... Can You make a test for it? Now i'm thinking to sell the APM... not cool at all...
Ps. What about the producer of the regulator says? They have to made some test before they sell it... What they say about their regulator failure? Maybe it's not a failure of bad board design but the bad QA of the regulators and thats is the issue?
Dennnis
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