APM 2.6 USB has died [Solved]



New to APM so maybe me?

I noticed that my new APM 2.6 just delivered seemed to have com6 and I was just trying to get the baud rate correct and it stopped communicating!

Blue/Red led still flashes, green light over GPS socket still green but no communications. Looks like something in the USB port died!

Clearly one dead APM.
Q: Are all APM so unreliable? It only lasted 10 minutes and cost £119

Is it possible to get it repaired?

Don’t really want to just buy another one and have that one die!

All the best



Found that the USB cable was bad!
Hiwever, still cannot get Mavlink to connect using USB?
I dont have gps connected?
If I go to terminal I can connect!
I do get errors: no dataflash

Then Arducopter v3.1.2]
If I test baro it says read unsuccessful for more than 500ms in AP_Baro_calibrate
In setup accel
FAILED TO BOOT MPU6000 5 times


Ok took case apart and measured a few voltages.
Seem to have lost the 3.3v on the mp6000!
Dont think I can fix that! Looks like a problem with the USB +5v has drawn too much current and taken out one of the two components right next to the USB connector.
The answer is! Dont have the power on the APM when you plug the USB in!!!

Expensive lesson…
Just bad design on the APM board to?

Anyone got the circuit diagram and board tracks so that i could provide an external 3.3v?


If you purchased the APM board from us recently we can probably repair it for you. Please send support an email with your order number and we can help.

Otherwise here are a few things to try.

  1. Try reformatting the dataflash chip. Depending on the firmware loaded, you may need to reformat the dataflash chip by going to the terminal, then logs, and then erase.

  2. Run some other tests on the APM via the CLI terminal. Try running the IMU tests to see if the MPU6000 is indeed faulty. Once connected to the terminal type, test then imu

For more detials on the CLI please see this wiki page


Getting very unhappy with the APM 2.6.
I think the software is not what you show above. My Test does not have half the lines you show.
I know the problem from my experience with other Arduino products (I use Mega 2560 R3 to build dome controllers for astronomy)
However…The APM is not designed as well as the R3. Power problems all over the place!
3.3V regulator issues cause most likely by Power loops.
My power loop was because I was powering the APM via the RX servo leads. (Why not?)
I then plugged the USB lead in and fried the two chip components next to the USB port.
This in turn took out a track that provided the 3.3v to the MP6000 and Baro.
Very little information on the 2.6 board layout and due to surface mount almost impossible to repair.
I am still trying to find a track (in my spare time) that I can insert external 3.3V from the regulator on the board.
All the terminal functions work. But as I said, I don’t know where you got your software, not the same as mine. Mine is Mission Planner 1.2.96.

While I am typing… Bought a GPS UBLOX NEO 6M that said APM 2.6 compatible. But it has all the wrong connectors? Just has 4 single connector wires red black yellow and green. Just spent the last hour trying to find out what all the pins are on the 2.6 - No luck yet. The group of 6 pins next to the GPS writing must be the ones but which is which?

Now need to find a compass!!!
I notice that UnmannedTech and xxRobotics?? Neither have information on 2.6 pinout…
I notice RCModelReviews is going to look at the APM - should make interesting reading.




I just wanted to follow up with this and see if you replacement APM2.6 board is still working fine and all the problems are resolved?



Yes all working and installed in my heli. But I have modified a USB cable to remove the +5v as this was the cause of the problem. I am also using the PM that I purchased from you after the last failure.

I have looked at the eagle files and it seems that it is quite likely that if you power the APM from a source other than the PM and use a NORMAL USB cable you will blow the 3.3v or the cable internal; wires. In my case the cable wire shorted due to too much current and blew the zener which for some reason took out the regulator.
But all works fine with the modified USB under all configurations.




It’s all so obvious in retrospect! I had a Ardupilot 2.6 (x-quad firmware) installed on a QR X350. Due to some glitch, sometimes when I connected BOTH the battery to the 'quad then the USB to the PC the motors would fire up. In panic, I disconnected the battery supply and stood there curiously wondering why the motors were still running, until it dawned on me that they could only be powered by the USB supply. Result - a fried MP-6000. I have ordered a new APM and only repeat this story to warn you not to be so stupid.



This failure is due to the USB lead supplying the APM with current in parallel with the battery.
I use a USB lead with no 5volt wire connected, If not you risk blowing your APM normally the 3.3v regulator for some reason.


Agreed Astrojohn - I saw your earlier post and the FIRST thing I’m going to do with the new APM is make sure I cut the +5v wire of the USB cable.


Hy guys. On mine Walkera QR X350 Pro flight controller died just by standing connected with USB cable while i was using Mission Planer. I didnt expect that it so fragile. When i’m using CLI i’m getting somthing like “firmware update…erasing EEPROM…done.” when i press CONECT button.


Does your X350 pro still work when you try to fly it? If not I suggest that you try to load the arducopter firmware onto the Devo M controller again to see if that will help? Possibly a setting was not saved properly which is cuasing a problem. You can also try to perform a factory reset. If you need the parameter files for the Walkera X350 Pro then please let me know.


Sorry for long delay :smiley: and thank you for respons. Controller is not capable to store any parameters but it does accept new firmware and shows that it is another version of FW. As long i have usb connected with quad, its arming. But just enough to disconect from CIL terminal,(not cable), its impossible to arm and all parameters are gone.Same whith battery on, or with main battery on and 5v usb voltage off (disconnected voltage wire). I tryed to check voltage regulator- it gives out i guess 5v or 3.3v. I dont remember now but at a time i didnt panik, so i guess was voltage ok :smiley: But is it any unusual long time i should wait after FW update??? What actually i could damage with MP terminal?Hope this is little bit more information :smile: I used original walkera software to upgrade FW. Bootloader???