A couple months back I won a 35A AIO from Fettec.  Last night I finally put it in a build. It's all plugs, aside from soldering motors.  

However, I noticed that if I have more than one motor soldered up, my smoke stopper will trip about 2 seconds into booting.  I took the chance and plugged in without a smoke stopper and it boots fine with no smoke, but I definitely smell burning, even with nothing else plugged into it.

There is no damage on either side of the AIO, either.  I'm guessing I got a bum board?

Get a jewelers loupe… do a real good inspection of ur solder joints..look for random solder balls on the board..
Does it respond as it should? Have you powered up the motors? If things “work” correct, it may have been some stray wire strand or something and possibly burned off..
If it were me, I would keep an eye on this quad when u fly for a bit.. also, there may have been a reason for this AIO to be used in a “givaway”..
You can’t REALY complain about a failing component when it’s free.. unless it fails, you loose the quad with a new digital video system on it..

I don't want to fly it at all...lol. It's a prototype frame I'm testing and also has an 03 air unit so I don't want to risk all of that going up in flames.

I swapped an identical AIO from another build and it works fine so in the meantime I'll inspect the suspect one further. Just odd that when I desolder any three motors it'll be just fine.

Something sounds wrong in the esc end of it. Whichever set of components splits the power across the four ESC's is maybe faulty. It can maybe provide enough for one esc, but not four.

For testing purposes, you could solder on 4 of lowest power motors you have, like some whoop motors and see if it would fly. If it does, well I'd throw it in your parts box, but if you ever use it, it's not going to be running Lipos with a big cell count. But it might work in a 1S or 2S type build. Obviously you would have to experiment to work out what sort of power levels it can safely produce and I definitely wouldn't put any expensive vtx or rx on it.

(20-Jan-2023, 07:41 PM)Pathfinder075 Wrote: Something sounds wrong in the esc end of it.  Whichever set of components splits the power across the four ESC's is maybe faulty.  It can maybe provide enough for one esc, but not four.  

For testing purposes, you could solder on 4 of lowest power motors you have, like some whoop motors and see if it would fly.  If it does, well I'd throw it in your parts box, but if you ever use it, it's not going to be running Lipos with a big cell count.  But it might work in a 1S or 2S type build.  Obviously you would have to experiment to work out what sort of power levels it can safely produce and I definitely wouldn't put any expensive vtx or rx on it.

I think I'll reach out to Fettec and see if they can do anything for me.

If you smell smoke its definetly wrong, and damaged. Either from your soldering/short or from factory.

If you want to isolate it, you need to unplug everything and try the board by itself. USB only. LIPO only. etc.

But, probably just get it replaced by FETTEC