Petzl Tikka XP gen 1 XP-G mod (pic-heavy!)

These are impressions of a recent Tikka XP gen 1 headlamp modification I've made. I won't attempt to explain it in detail, since the original XP-G mod thread started by szemhazai - the headlamp modder extraordinaire - is available over on CPF.

So I've decided to give a new life to my trusty 3xAAA headlamp, which had served me well for years. I've managed to buy unknown-flux-bin, unknown-CRI Cree XP-G Neutral White (4000K) bare emitter in a local electronic component store. "Bare emitter" means no star and no micro PCB to elegantly solder power wires onto... My soldering techniques were to be put to the ultimate test, since the main goal here was to solder wires to points on the upper surface of tiny emitter (3x3mm footprint!) not destroying it in the process (AFAIK, Cree prohibits hand-soldering on these emitters). The rest of the mod was supposed to be a piece of cake, ehm...

My Soviet-era 40W soldering iron received a pointed "pigtail" adaptor to its tip, to allow it to make microscopic solderings (the absolute cheapskate/gonzo solution).



I've also bought a Chillaramic nano-ceramic thermal compound, to restore heat transfer bridge from XP-G to improvised heatsinking components underneath it, and to thermal protection sensor on the bottom. Bison brand 1.5hr 2-component epoxy was used for fixing the emiter and mixing with thermal compound. Wiring was scavenged from old electronic devices. I already had Torx T6 screwdriver, which was needed to disassemble this headlamp.

Here are the pics:

Wires, bare star (reused generic "1W"), and a midget XP-G emitter in its black blister packaging. Nichia GS 5mm shown here for size comparison:


Improvised micro PCB that I've made out from a star, using a rotary tool with cut-off disc. It's a small part made of aluminum (heat transfer is excellent), so watch your fingers:


Micro PCB with wires, ready for emitter soldering:


Scraping off protective lacquer from the top soldering points of the XP-G. Blade point and scrapings are visible. Polarity is clearly marked on the emitter. Good magnifying glass is an absolute necessity - mine is actually a LOMO camera lens :


Soldering iron approaches its target: improvised copper tip is visible. Wires and soldering points are clean, and a small amount of flux is aready applied. What you need here is a steady hand: one wrong move or too much heat = POOF! After soldering, thermal compound is applied on the bottom of the XP-G's footprint, emitter is pressed against the PCB and potted with epoxy glue. Chillaramic compound is electrically non-conductive (Warning: metallic compounds should not be used here!). And, be careful not to touch or mess up the emitter's dome with gunk!


View of a star (clean side) and thermistor underneath: thermal compound is wiped off. Original Luxeon emitter is removed with a box cutter; solder bumps and lacquer are stripped away with a coarse metal file. To retain thermal protection feature, thermal compound should be applied between the star and thermistor prior to re-assembly.


Improvised thermal glue on the bottom side of micro PCB (actually a mix of epoxy glue and a thermal compound). PCB has to be pressed firmly on the star, since thinner layer of thermal glue means better heat transfer (i.e. cooling!):


Test fitting of emitter holder (round black plastic part). Thermal glue has partially set (potting time 1.5 hrs). Holder itself had to be modified to fit over the emitter as low to the star as possible:


After soldering emitter supply wires to the main board, you can carefully assemble two halves of Tikka XP's shell, insert batteries and check the beam pattern. Leave the screws aside until you're completely satisfied with the beam.

Correctly fitted emitter and optics should produce the same thick, round, artifact-free hotspot as it was before the modification. However the hotspot on my Tikka had a round center with a faint square outline (shape of the XP-G emitter die!), which was just enough to make me annoyed. Emitter was well centered and throw was excellent too, even with old Chinese AAA's, so the square-outlined hotspot was a purely aesthetical issue, but coming such a long way I wanted a perfect beam. I couldn't move the emitter further toward the lens to correct the hotspot outline, so I started experimenting with self-adhesive diffuser film, placing it on the outer surface of the lens. A full lens mask produced a great floodlight, but I was looking for a result as close as possible to the original rich, well-defined throwie hotspot produced by a Fresnel lens. Finally, a smal patch placed on the center of the lens produced a desired result:


And now a couple of beamshots:

Left: Jetbeam PA01 on High (140lm OTF), Right: Tikka XP-G NW on High, focused (not Boost)


Left: Jetbeam PA01 on High (140lm OTF), Right: Tikka XP-G NW on High, diffused (not Boost)


4,000K Neutral White still looks a little bit colder than ordinary household frosted bulb. Experimental diffuser film patch is visible on the Tikka's lens:


Comment:

I think this mod was well worth the effort, since I now have powerful and fully functional neutral white headlamp added to my collection, for the price of only 14 Euros paid for the emitter and thermal compound. Color rendering with the new XP-G is much better compared to any of my other (cool white) flashlights, and throw is just awesome. I can't judge about lumens/lux since I don't have the necessary equipment, but improvement in performance is simply astonishing

Cheers,

Tam