Update on my (self induced) melted centring ring leading to un-planned de-dome:
Found a thin red-fibre washer that fits exactly around the LED die.
Glued it onto the back of the reflector after very careful centring. (Temporary fix with bits of tape until perfect, then some tiny drops of superglue).
Careful fitting, sanding down, re-fitting etc until it fitted perfectly with the bezel almost but not quite bottomed out.
A dollop of Arctic Silver under the star, then time to test. Laptop pull used initially.
Oh dear, near field beam looked like the rings of Saturn around the hotspot.
But backing off, beyond six feet or so it is quite nice, except for one ring around the hotspot.
I think it may be coming from the transition between the flat bottom of the reflector, and the (parabolic ?) part.
The hotspot is tight, and remains tight at long distance, so its near enough focussed.
As Dale predicted, my naptha de-dome has changed the tint, considerably warmer, but yes there is the tiniest hint of green.
Left it to “burn in” on turbo for 15 mins, got noticeably warmer at the head than in original state.
The out with the Efest 35A at 4.19V and multimeter with short stout leads to measure tail current.
One brief flash, and that was that.
Driver is working, there’s 4.19V across the LED.
Difficult to tell under x10 loupe, but I think the bond wires have gone.
So I do not recommend a de-dome of this LED
Lesson learned.
PS: anyone got a suitable LED on a star going spare ?
PPS: I can confirm that the head of the torch is fully anodised inside.
So the only current path to the driver is through that shouldered securing ring.
Looks like it was a cost reduction exercise to eliminate a masking step during anodisation. Without it fitted the head screws down an extra turn, so I’ll be looking to grind the shoulder down as much as I dare, when I rebuild it.