problems with Eachine f3 brushed FC

LUCIFER

Member
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!!!!!.
 

LUCIFER

Member
Here's a picture of my flight controller
 

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LUCIFER

Member
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.
 

FDS

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.
 

ElectriSean

Eternal Student
Mentor
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.
 
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FDS

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.
 

LUCIFER

Member
The SMD component on one of the M6 pads,is what is missing on M4. I don't know if it's resistor.
 

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FDS

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?