Replies to This Discussion

Permalink Reply by John Culp on May 29, 2012 at 6:49pm

3DR wrote me "...f you would like, you can send the APM2 back to the store for repairs or a replacement and we will check it here. You can also power the APM2 from the inputs, and you will need a separate power source to power the outputs rail."

Are there advantages/disadvantages from powering from the inputs.  I guess this could be done with a Y on the BEC  lead on the ESC?  Is it better just to run a separate BEC from the battery?  Can the USB and flight battery power at the same time the APM2 if you bypass the diode?

Thanks for your patience and help.  The APM is quite new to me and I don't have an electronics background.

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Permalink Reply by TJ on May 30, 2012 at 5:55pm

John, I'm not an electronics expert by far, so please don't hold me to my suggestions here.

I do a bit of hobby electronics. I make my own simple circuit boards and projects.

As you suggested, you could still use your ESC power output to power the input rail. We are supposed to only be using one of the ESC's BEC outputs to power the board as per the documentation. Ground should always be distributed to every component of the system. That said, you would want your ESC's to be connected to the output rail with the ground and signal wires only. You would carry ground and one of the ESC's BEC output over to the input rail. 

The same could be achieved with a separate BEC but at the expense of more wiring, weight and just isn't necessary. As for powering the board via USB and BEC on input rail simultaneously is one I'm not able to answer. Please let us know if you get this information out of 3DR. There is potential for a voltage or current differential if the circuits are not isolated properly and I'm afraid the design of the board is beyond my understanding.  (may very well be the problem with the APM2 as it stands).

Being open-source minded that 3DR is, it would be great if they would just clearly explain the problem we are seeing.  I have to wonder if they are reluctant because of a design flaw. It happens, boards are revised and further developed. Companies take care of the mistakes professionally (3DR seems to be doing so), and continue to produce greater and greater products. I hope this is the outcome for us as consumers and 3DR as a company.

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Permalink Reply by John Culp on May 31, 2012 at 1:37am

Thanks TJ, I decided to keep it simple and send the board back. 

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Permalink Reply by John Culp on July 6, 2012 at 3:36pm

Follow-up. Got the board back last week, but am having a new power issue. 

The APM2 works perfectly when powered by USB, However when I connect the plane battery the GPS led on the APM2 board goes out.  The external GPS led  remains lit regardless of the power source (no internal GPS on my APM2). When I plug the USB in the GPS led stats working if the plane battery is disconnected. When connected to the plane battery and not the USB I can press the reset and the LED turns blue for a second and goes black. 

In flight, the stabilization function appears to be working normally. RTL does not work. 

I have a Turnigy Trust 55A bec powering the board. Factory specs:

Spec.
Max Motor Current: 55A
Max BEC Current: 3A
BEC Voltage: 5.5v (Switching)
 

I measured the output at 5.62v and measured 5.37v on the input rail. Appears normal but blue and red led flickers and then goes black.  The manual on wiki says: "5.37VDC +/- 0.5v supplied into the PWM output connector, jumper JP-1 in place"  So 5.62v should be within spec. 

 

When hooked to the usb the input rail measures 4.45v - Works normal.

 

I connected a standard 5v nicad pack with output of 5.15 to the input and got a reading of 4.78v on the input rail.  Works normal.

 

I connected a standard 5v nicad pack with output of 5.15 to the output and got a reading of 4.75v on the input rail.  Works normal.

 

I'm waiting to hear back from 3DR.  

 

Would it be advisable to pull JP1 and run a separate 5v bec to the input rail and power the output rail with my esc?

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Permalink Reply by Carlos Martinez on July 26, 2012 at 6:57pm

 

Who know where I can buy  3 zener diodes 1N5233BDITR

 for my APM2?

 

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