APM 2.6 Problem

[GlassKnees]

I have an APM 2.6 controller on a quadcopter that I recently rebuilt. It has flown successfully a couple of times, but arming the motors is a hit or miss affair. Several times, the motors fail to arm, so I removed the props, brought it into my home, powered it up and established a telemetry link with Mission Planner on my desktop.

When I try to arm the motors, I get a "No RC Receiver" warning, which is odd because if I had no receiver signal, the APM wouldn't know that I was trying to arm it in the first place. I successfully performed the radio calibration, so I know that the transmitter, receiver and APM are all talking to each other. I re-flashed the firmware and went through all the calibrations to no avail.

The radio failsafe is set to RTL, so when I get the "No RC receiver" warning, the APM must go into RTL mode, because subsequent attempts to arm result in a "mode not armable" warning... Switching flight modes does not clear the problem.

I've searched other forums and there is a history of similar behaviors but so far I've found no solution except that one guy replaced his APM and the problem went away. Has anyone on this forum experienced this problem and have a solution you can offer?

 

[mozquito1]

Check all the solder joints or just Reflow them to be sure.

 

[Jackson]

Maybe?

 

[GlassKnees]

I remember watching this video back when I first started using APMs. Unfortunately, it is no help - I'm in Stabilize mode, I've successfully completed the radio calibration as stated previously, and the APM has to be communicating with the radio, otherwise it would not know that I'm trying to arm the motors. I am confident of my solder connections and other connections as well. Mission Planner nor the logs offers any more help...

I have a buddy down the street that has a spare APM - will get it and see if it works better or not. In the meantime, I am grounded....

 

[mozquito1]

Usually if somthing is only working intermittently or when it wants to, it's down to a bad joint. Like you say replaced the whole fcb. It may have just been that he solderd it properly the second time.
The board taken off may have been OK.
Invest in a multimeter & check every joint until you have the experience to tell if it looks good or not. The gyros on them old boards a not very good anyway.

 

[Jackson]

I'm in Stabilize mode, I've successfully completed the radio calibration as stated previously,

Sure seems like there is a whole lot more than that to it.

 

[GlassKnees]

Success! I bought an unused APM 2.6 from a neighbor, installed the firmware and went though the configurations - it works! I can arm and disarm at will.