It's so sad to see all your hard work fall from the sky like a rock.  This past Friday after work, I tried to fly my usually circle flight plan at a field next to my work.  Everything seem normal, I switched to ALT HOLD and then switched AUTO and off it flew to waypoint 1 at 20 meters right in front of me.  It had a 10 second delay, which it never finished.  I'm not sure yet what happened, but it just fell like a rock.  It landed upside down and damaged 3 arms and 3 motors, plus the stack on top broke all it's supports.  About $90 of parts, which I ordered Saturday.  And, I'm happy to report my order from 3DR has shipped tonight, I should see them Friday. I'm really happy they turned my order around so fast.  Brownie points to 3DR and staff.

Now can someone give me some pointers on what I should look for and test to see why my copter failed?  I really don't want to fly again until I figure out what went wrong.  Last week I had tuned my gimbal thinking it was causing power problems and some weird twitching and 1 minor crash. I recently just added 3DR power module and pulled JP1, hoping this might help with power issues.  I had 2 successful flights and now this crash.  I also have a 5 amp BEC plugged into the output side of APM, plus 3DR PM.

I'm sorry to say the GoPro failed to capture the last few seconds of the flight.  Bummer, the last time I had a brownout the GoPro showed a great tumble to the ground.

I've attached my tlog, kmz and log files for review.

Firmware is 2.8.1.

Recently balanced props and mounted APM on foam corners.  I was just about to upgrade to 2.9.1. :-(

Thanks for the support.


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Thanks @Thomas J Coyle III and Bill Bonney:

So, just let me summarize:

I disconnect JP1.

I use the +5V of the APM2.5 Power Module to power the APM2.5

I connect the UBEC +5V and GND to the output pins next to Ch10/Ch11

This way I can power the APM2.5 and at the same time the servos with clean UBEC power?

> disconnect JP1.

>I use the +5V of the APM2.5 Power Module to power the APM2.5

>I connect the UBEC +5V and GND to the output pins next to Ch10/Ch11

Outputs are the pins marked 'Outputs' 1-8. CH10/CH11 are marked A10/A11 on the side of the case.

All the 5V/GND pins on A0 to A11 and Inputs 1 to 8 are all connected together. If JP1 is in place 5V/GND from A0-11 Inputs1-8 would be connected together, removing it disconnects Outputs 5V from the rest.

>This way I can power the APM2.5 and at the same time the servos with clean >UBEC power?

You could as you have also suggested just connect the 5V directly from the UBEC to servos (5V/GND) and take the signal and GND to the APM (you need the common GND)

Anway, I hope that helps explain the purpose of JP1

I think I get it now

Everything except for Output will be connected if JP1 is removed.

So my APM2.5 Power Module will power up my APM2.5 and receiver.

To get more power on output and my Servos I disconnect JP1, then plug my UBEC into Output1 (e.g.) then put Servo+/- into Output2 (e.g.) and take signal from Ch10/11.


It's a bit confusing I must admit.

Thanks for your help Bill. Much apprechiated

You are right. See this post and it should help

Here's a picture of how I look at connecting power to the APM 2.5. You can connect power to any pin on the 5V rail. The protection diode stops you power anything connected to outputs if the 5V in is connect to the inputs and A side. The 500mA fuse limits the current you can use on the Inputs & A side if you use the PM or connect 5V to Outputs. This shows how JP1 connect Outputs to Inputs and PM.

Hope this helps :)

I'm kind of a visual person, so I've drawn out a couple options.  Can someone take a look at my 2 options to powering my camera gimbals.  Which one is correct?  Also, how do I connect the ground (which I assume is "-" connection) to both locations?  Do I solder an extra wire between both the signal and power to connect a common GND?

Below is Option One:

Below is Option Two:

Thanks for the support.



Check out Bill's excellent illustration above. 

The most important thing is that you're not drawing a bunch of power out of the Input-Analog positive-rails.

 You'll notice that +5.3V travels from the power module, through the protection (fuse, diode) where it looses .3V (as a side effect of the diode), travels via circuit board traces to the positive-rails of the Input and Analog. That circuit path is only designed to power your Rx, sonar, 3dr radio, etc.

The ground rail is common to both sides of the board (Output and Input-Analog).

In your Option 2 diagram: the power module connects to APM negative and the v-reg (BEC) connects to APM negative.

Regardless of JP1 all the APM negatives are connected.

The gimbal servos are connected to APM neg. at the Output, there is no need for a second neg. connection from the Analog side, just the signal wire.

You just need to make sure that the GND from the BEC connects to the GND on the APM at one point. ie. common ground. i.e. all grounds are connected together.

You only have to connect GND once (see my diagram) as they are common. then you just need to connect the rest/

Option 1: This will supply 5V from the APM PM, and will conflict with the 5V from the BEC. disconnect the APM PM line 1 & 2 from the cable connecting it

Option 2: This works without disconnecting wires from the DF13 cable from the APM PM. Make sure that the ESCs do not have 5V lines to the Outputs or only connect the GND from the PDB to the outputs.

So option2 will work without burning any fuses?

Maybe LED connection will be safely powered this way, too?


I too am trying to figure this out as I have three servos (pitch,roll,trigger) and I too am a visual person.  so is option 2 correct as it's draw or does their need to make adjustments? 

Also can the BEC be soldered to the PDB 5v output or does it need to be solder directly to the battery via the battery connector?

I actually did a modified version of option 1. I hooked up only signal to the gimbal from channel 10 & 11 and hooked a common ground on one of output pins to the ESCs. I still power the gimbal via a seperate BEC. I'll try and upload an updated picture. I've not flown like this yet, but I've powered everything and it seems to work ok. I'm waiting for winds to drop off to do a test flight. Also I'll be flying the new firmware 2.9.1.


How did you hook up the BEC to recieve power?  Can you solder the BEC to the "5v, GND" off the PDB?  or do you need to hook it straight into the battery connection?  Would love to see a picture of your set-up



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