wiring/design issue with Magic Pie PCB

[dirk pitt]

our association is making some experiments with an off-road wheelchair equipped with 4 MP.
unfortunatly, we just burned two MP controllers within a few days. the reason seems to be due to the wiring in conjunction with the bumps in off-road conditions.
it is a pity as the MP is really good compared to the other motors we had before on the same wheelchair which ran about 3000kms off-road without any problem.
The first notice is that the state of the wire insulation from motor phases is quite bad.(see picture)
after unsoldering, it appears that one of the motor phase wire had a contact with the negative track on the board (see the copper appearing on negative track)
why this bloody negative track is passing all along the motor phases tracks!! too closed to the motor phases wires.
also the space between tracks of the phases is very narrow and as the soldering is "not so good" this is an other potential risk.

Last point: I am not sure but it seems that the PCB is not protected against moisture (varnish or resin) and the inside of the motor is a perfect condensation place with its aluminium walls. I found some first traces of rust and moisture attack on the iron of the coils and on the PCB

[Leslie]

That rust is bad for a new motor.  I only had this problem when I sealed my motor up.  You cant seal this motor even with good materials as the pressure inside will blow your seal out or find a leak through the housing wall seats, and the atmospheric back pressure wil push the air back in when it cools.

Nothing is undoable but the smallest of failure to seal the motor will always results with water on motor.

Not saying you did this but the another person may of tried to seal the wire port of the motor to make it more "off road".  If this isnt the case here, why does this happen to some motors and others not.  The mind boggles.

While your at fixing this motor dip the stator it in heat tollerant SR3 varnish or something like it.

There is a motor rewind contractor local in my area who does it for cheap.

The GM PCB isnt the best one Ive seen.

[dirk pitt]

for information, I had a look to the MOS: they are from ST and have the ref P140NF75 rated at 120A
The capacitors are rated 63V