Hi, I bought a complete APM 2.6 system 2 months ago. I have mounted it in a fpv plane and it flew 2 times with no problem. But today, I have connected it at home to adjust PID´s with the computer and when everything was working (it was connected by telemetry), I started the motor and when it was running at half throtle (I was measuring 27A current in the Mission Planner HUD and with an external ammeter) it became a white smoke from the Power Module and it burnt. I disconnected inmediatly the battery but the Power Module was burnt. Then, I took all wires out and tried the APM sepparetly (alone, nothing connected to the APM) by the USB to the computer but it didn´t work. Now I have oppened APM case and I can see at least 1 smd item burnt. It is the one marked with an "H" between the PM connector and the ATMEGA.
I´m sure everything was well connected becaused I had flown 2 times before with no problem but now the Power Module burnt just at 27A and it caused the APM also burnt.
What should I do? I´m sure it was a defective Power Module and it caused the APM burnt. I don´t understand why the APM is not isolated from Power Modules burnt fails.
Here are some photos of the power module and the AMP with the fried component.
What could had happened?
What should I do?
Thanks.
Replies
That burnt component with the H looks like the 500ma fuse. I also noticed that the lower left two pins of main chip are black as well as the 6th and 7th in from the left. I am guessing that the lower left two burnt because they are close to the burnt fuse. The 6th and 7th pins in are Vcc and ground so either they shorted out somehow or naturally got burnt from the power spike.
And finally the elephant in the room...where on earth is your HMC5883L compass chip? It should be a little to the right of reset button. Maybe it is there but the photo is bad?
Unfortunately I have no idea what the root cause was.
I think the micro is fine because all pins are rigth soldered and everything looks fine.
What about the HMC5883L compass? I don´t know what are you talking about. Please, explain it to me.
Here are some more photos:
I have powered the output line with 5.2V , I measured before the diode and it vas 5.2v , the I measured between the diode and the fuse and it was 4.7v , then I measured after the fuse and it was 3.8v . But I had to press in over the second pin of the fuse to get this reading (maybe because the fuse doesn´t have a good contact due to it is burnt. When I do this, it starts to light the "alive" led and the red one next to the outputs rail starts to blink 4 times and then gets off continuously (it seems to be a power error light code). What do you think?
Now I have taken out the fuse (the burnt one) and put a little wire between both fuse pins in order to know if the problem was just the fuse or anything else. When I power it with 5.2v happens the same as explained before: the "alive" led gets a solid green continuously, in the output rails the blue led (letter C) blinks 3 quickly times and turns off (I think it is normal) but the red led (letter A) blinks slowly 4 times and then turns off continuously, but the "alive" one is still green. So the problem persists even with the fuse "solved". If I can I will put a video here.
Any idea?
Measure the voltage across the outermost pins of the i2c connector. I marked them with red dots. You should get 3.3v.
You are missing your compass chip and a 4.7uF capacitor. Are you using an external compass module? The missing capacitor is probably not that big of a deal but these missing components make me wonder what else was wrong from the factory.