The intent was to wire the “5 W” COB LED to the 12 VDC supply grafted on the Juki TL-2010Q, through a suitable resistor around 18 Ω. Unfortunately, the next morning I managed to run 12 V directly to the LEDs, which produced an astonishingly bright flash of blue-white light and an opportunity for some post-mortem analysis.
A sharp tap with a chisel popped the COB LED PCB off its heatsink:
That’s a pretty nice thermal joint and ought to transfer as much heat as reaches the back surface. Mechanically, it yanked one of the nickel tabs right off the solder pads; obviously, I must now level up my soldering game.
Scraping the yellow silicone filter off the PCB reveals the minuscule LEDs:
You’ll recall they’re arranged in three series sets of six:
Some probing revealed five of six LEDs in one set was still functional:
Although a few other LEDs across the PCB survived, that’s not the way to bet when you run so much current through the poor things.
Ah, well, that’s why I always buy a few more parts than I really need …
The Smell of Molten Projects in the Morning 
Oops. It’s the brightest they’ll ever be … but only once.
Live hard, die young!