not sure as to whether it really fits into the projects category of the forum, as it is more or less 3D printing related.

i recently acquired a BIGTREETECH SKR V1.4 Turbo board to play with MARLIN 2.0 firmware and (hopefully) later implant it into an UM2+ just for the lulz. while studying the board's documentation, i noticed that the heater- and fan-control outputs do indeed incorporate some beefy 40 V MOSFETs, but are lacking of any protection against inductive loads, aka freewheeling diodes. shame on you, bigtreetech!

to overcome this potentially hazardous issue (think of a blown heater MOSFET and the board no longer able to turn the heater off), i prophylactically equipped the four outputs around Q1, Q2, Q3 and FAN0 with some schottky diodes that i had in my stash.
each of them is bodged with their anode to the respective drain and their cathodes all routed to +24 DC after(!) the 20 A fuse.
maybe this post will help anybody who is planning to use this board and save him/her some blown MOSFETs!
famous last words: use this mod at your own risk.