The 2DM860H chinese controllers vs the rest?

[Kitwn]

Super job and an excelent set of pictures and video. I'm jealous of the range of test equipment. Who'd have thought I could infulence the behaviour of someone so far away

You haven't used any tools that most builders aren't going to need anyway to fit all the plugs and sockets on a machine (I'd add a solder-sucker for clearing out the holes) and my only gripe would be the lavish amount of heatsink compound. Nice to think Dean will be sending you a pallette-load of stuff to repair.

[Doddy]

my only gripe would be the lavish amount of heatsink compound.

I agree - the problem is twofold here - there are isolating pads currently stuck (I use the term guardedly) to the heatsink - using a little bit of heatsink compound. There's no registration of the actual devices to the pads, and no mechanical means other than the PCB stand-offs (and bolts) to mechanically couple the devices to the heatsink. So, you're relying on the stand-off of the device from the board to mate with the heatsink, and/or the blob of compound to provide a conformal interface with a reasonably low thermal resistance. I've not been able to find from the data sheet if the device tab is electrically connected to the silicon, but a test of one of the fails devices suggests that it is - which warrants considerable caution with maintaining the superficial mechanical registration with the pads. The usual approach of a thin film doesn't work in this situation.