I am having some trouble with my APM 1.0. Suddenly my APM 1.0 will not take power from the servo rail. Even if I plug a 5v battery to the servo rail, red in the middle, black on bottom nothing lights up. If I have my RX plugged in, some power backfeeds through the signal wire but there are clearly brownout issues that way. I tried unsoldering the SJ1 jumper and powering via a 2s lipo, which clearly powers up both boards great, but then the signal from my receiver does not seem to make it to the APM as the PPM light does not flash and the APM is unresponsive to radio inputs. I can power the whole canole off of USB power as well, but my motor outputs seems to be not active when I do that, and my motors beep away. This thing was working great last week....
The problem may have been associated with updating to the latest mission planner and code which I did this morning, but I tried rolling back the code to something much older (via arduino) and I have the same issues. At the same time I switched codes, I pulled the APM out of my airplane and into the Quad (the reason for the code update), so it is conceivable I caused damage, but I really don't think I did. Any help would be appreciated.
Check your F1 fuse on the APM.
Here is a simplifed schematic of the 5V distribution between the 2 boards.. (click for larger image)
This schematic assumes you are using the PWM header for input power from a BEC/ESC. I have included the JP7 on-board voltage regulator in the event that is being employed.
The schematic shows you that USB can provide power (to a limit - also a fuse) and the APM will look fine. If APM F1 is open, dead set.
I appreciate the reply guys, I'm going to pull this one out of the box and check it out tonight, I admit I had written it off, but would love to have my old APM 1 back.