After slowly ramping up to a normal voltage of 12 volts to the board the mosfets down the bottom of main board got really hot, so must be a short there and most likely on the others too as well as maybe internal short on chips or through multi layered pcb.
So with a short on the main board and how badly corroded the mosfet area was, I decided to remove every mosfet!
1 Z342 missing from above photo, there should be 12 of those.
As you can see a lot of the above had a lot of corroded/Missing pads.
Once this was done , no short and connected the 12 volt input and nothing was getting hot.
Although with no power mosfets in , not much going around the board anyway.
A lot of corrosion on the pcb pads, maybe with some flux and tinning area can clean the pads back up without having to make jumper wires up 😉
(The 2 red wires were just in place of the normal lipo connector as this was weak not being in shell and also getting in the way to measure voltages etc)
The Motor pre driver chips of which there are 4 on the board are MPS MP6530 (Three – Phase Brushless DC Motor Pre – Driver)
And the other power mosfets which there are 12 of them seem to be Vishay SIZ342 (DUAL N-CHANNEL 30-V)
Best way forward now?
Use as spares…..
If I get bored , I might for a laugh get new mosfets and fit them back just to see if anything happens.
But with corrosion around wi-fi chips and other exposed chips , almost certainly replacing all the mosfets will not bring this back to life, just too far gone.
But intresting to see just how much damage will happen if electronics on a quadcopter like this will take if it lands in water, especially salt water as this one did and more so if just left to dry out.
Think twice if you ever offered a water damaged quadcopter, the machine will 9 times of 10 need at least a new main board at the very least….
I may use the shell with new bearings in the motors with something like a naze32 or pixhawk board in the future.