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problems with Eachine f3 brushed FC

Hi guys,I need help,my eachine f3 won't arm and it won't connect to betaflight. It did connect to betaflight at first,and everything went fine,until I soldered third brushed motor.I soldered two motors first and then connected my FC to lipo,I was able to arm it and even able to spin the motors for a while.After installing the third motor,f3 won't arm,all I get is a solid red light on my FC. I was supposed to get three flashes of blue light and then solid red.What should I do?,please help!!!!!.
Hi again Mr Sean,you guided me before with same build.I think there is nothing wrong with my connections,but i will post a picture soon.I think I may have accidentally desoldered a small resistor,I don't know for sure.It is so hard to solder anything on a brushed FC.


Elite member
I prefer the version with plug in motors, or adding plugs to that board, it makes replacement easier.
Also it sounds like your soldering iron is on the large side for small board work. You shouldn’t get random components falling off if you are putting a reasonable amount of heat in.I would recommend a 25w iron with a needle point.
I suspect you have shorted something, maybe by melting solder across an ancillary connection. If you didn’t use a smoke stopper and plugged a battery in it’s likely that permanent damage has been done.


Eternal Student
Ideally you want a high power, temperature controlled iron. This lets you get the proper temp in quickly. The longer you are applying heat, the more likely you are to do damage. Low power irons take forever to get the components hot enough.


Elite member
It could be a resistor, you need them across the gate and source pins of the mosfets. The FET won’t work without it.


Elite member
I would have to see the circuit diagram for the board to find out what went where. I am not clever enough to work it out by looking at it, sorry! What soldering iron are you using?