A potential issue with the TerraLUX TLE-6 Drop-In

…and the similarly constructed ones…

Lately I noticed that the SSC LED of my TLE-6EX Mag Drop-in (4D) had a gap between its base and the heatsink. I had planned on putting some thermal epoxy there but yesterday I found out the gap has increased! Now it is about 1mm long!

I removed it and found out that the heatsink is dislodged from the module.

Now you got to understand how the module is assembled. In a PR bulb socked the board is placed along the top-bottom axis. And there are two wire leads that stick out from the boar. The cylindrical heatsink is place over the assembly, the leads pass through two holes at the edge of the heatsink and then the LED is soldered on the leads. In effect the heatsink is sandwiched between PR base and LED.

It turns out that when I screwed the module in and out it would glitch a few times. I located the glitch point on the post spring and the module lower tip junction. I had discounted the issue but it seems this is the reason that the module and its LED were dislodged.

In effect while you screw downwards and the spring resists upwards catching the solder tip of the PR base, the force is directed upwards tending to separate the LED.
The first fix was to examine the PR base tip and it was scarred. I put a little solder to even it and it screwed down evenly only to glitch and catch upon the next replacement and get scarred again. Upon closer inspection of the MAG post spring I found out its spring wire end is squarely cut. Not at an angle but just cut like you would with a scissors.

The only alternative was to fill the heatsink and LED gap with Arctic Alumina paste but this is in vain. Running the flashlight about 10 minutes changed the light color to "cheap 5mm led" blue and dropped the output at 1/3 (from about 300 Lux in my lightbox to 120).

So I forego of any further intervention until you hear from you guys. Should I add a .30 copper disc I have bellow the LED with thermal epoxy or go directly to the other way leaving the LED on the air?
(Seems to me that the heatsink is running hotter than the LED)

And the real scary thing is that a friend, under my advice bought two of them…

Hoping for your input, Kostas

One general point -- you don't want to "fill gaps" with any of the goop thermal pastes. They are _nowhere_ as effective at conducting heat as actual metal (copper or silver). They are meant to be put onto polished surfaces in tiny amounts, scraped off with something like the edge of a credit card, leaving just enough to fill the microscopic irregularities in the surfaces. Then press the surfaces together.

Check all the computer hotrodding websites on this.

Apple got embarassed not long ago for gooping excess thermal, er, goop, underneath one of their laptop CPUs --- causing them to overheat.

This is why they put those little bolt holes on CPUs and LED stars -- to physically screw the heat emitting thing down firmly onto the heat transporting thing, with the smidgen of thermal paste in between.

Someone will come along and improve on this, it's just amateur memory.

thanks ahnk O sorta knew it from a previous mistake...Did it before I realized i had a spare copper disc, wonder If I can solder it on the heatsink.....