Got one of the drivers wired up for power and hooked the linear supply direct to the mains feed (just to check operation)
The driver green led came on and got 72V across the power terminals. Then switched off to see how long it would take to drain the caps. It was dropping just under 0.5V per second so took a couple of minutes to drop to a low level (obviously will be quicker with all three drivers). But strangely it stopped at just under 4V and stayed there. I waited but it did not go any further. In the end I held a 10K resistor across the cap terminal to drain it right down. Why did the voltage stop? Must be something in the drivers that stops drawing current at 4V?
This means there will always be a bit of energy stored in the supply long after it has been turned off. This bothers me a bit so I may add a bleed resistor permanently. Anyone else checked if their power supply drops to zero?