I’m pretty much done with soldering Luxeon V’s to 3535 boards :weary:
After succesfully modding a 21700 Sofirn C8F with Luxeon V’s a few weeks back, over 5000 lumen output, after a day or so I noticed that one of the leds lost half of its die working, and so output went down with that, 4500 lumen. Can’t stand that of course so I spent a few hours last week swapping the faulty led to a new one. After assembly: again one led that only lit up half (I did not registrate if it was the new led or one of the others). I really want this mod to work, so yesterday evening another go, new led, of course also some tiny wires broke off driver, resoldered them, minuscule solder pad ripped off, created new solder pad further down the trace and fixed wire, closed head, led-minus was shorted to body because of some twisting action while screwing reflector tight, opened up, changed led-wires, closed again, all was working….except one led only half lighting up :person_facepalming: , still 4500 lumen.
The probable reason is that for one 4040 led to be reflowed correctly on these wrong 3535 pads, it has been reflowed, checked, removed, and reflowed again on average 8 times before succes, times three (it is a triple) is 24 cycles of heating up and cooling down of the board, while far from following the adviced thermal regime for reflow from the datasheet. Apart from the heat stress, it makes the solder brittle and likely less thermally conductive.
So being many hours and three expensive LuxeonV leds down, and I’m going to find new leds for this host
As you might remember there were several members reporting the problem with the half lit Luxeon V in the beginning of this year, including me. I haven’t even reflowed this LEDs by myself, I bought them already reflowed to MCPCB. Meanwhile I believe they are either all of bad quality or quality is not constant during batches. I don’t consider buying more of this LEDs.
Where could I buy LH351D in good price to ship central europe free or very reasonably shipping cost?
I asked Sofirn if they want to make 4040 and 5050 MCPCB for C8F sold separately or option at buying host.
Split a 50 euro order (free shipping minimum) with someone and choose multiple CCT’s from a large digikey selection. They have 18 different bin/color choices (check datasheet for models cause not all are categorized properly):
Installed one of Lexel’s D4S aux boards. I went with pink/purple and green for the main aux leds and then there are 3 red LEDs in the middle that indicate low voltage and finally off entirely for complete LVP.
A bit trickier than I expected but still managed to get it done without too much trouble.
Some observations:
All 4 wires have to be pulled through the middle hole then soldered from the top through the adjacent holes
I dont think it’s possible to sit 100% flat where the LED wires solder to MCPCB, just too little room and your solder blob will slightly raise the middle. I still screwed it down pretty tight on all 4 ends but the board is flexing slightly on the outsides
I guess because of the potentiometers only the “high” and beacon aux settings work, then you just adjust it using the 3 pots
- yes the first version had not ideal holes for the main LED boards pads, fixed this on later boards which will be available soon, simply had no D4S to measure the right distance
- low mode can not work as its PWMed
- LVP and low battery warning with 3 red LEDs when outer 16 are shut off
driver can not be flashed when Aux board soldered as its a cap on a programming pin for the LDO
