I’m new to all this and after switching out 5 or 6 mcpcbs, it’s time to try a reflow.
This S43 apparently has Nichia 219c 5000k emitters in it as stock. They were a very neutral to cool white which didn’t appeal to me so I thought I’d make it my first go. I ordered 4x 219b sw30s from forum member azhu for this. He delivered them well packed and beautifully labelled.
The bezel unscrews easily revealing a glass and quad optic. Pulling out the optic shows the mcpcb fastened with 2 screws. Undoing them and unsoldering the wires, the board comes out easy. I cleaned off the thermal paste residue on the board and in the head.
I did a dry run a few days ago with a blank pcb that had solder on the contacts. I used an old frypan (that won’t be used for food again) and turned it up one step at a time, allowing time to heat on each level until I noticed the point at which the solder melted. So here is the S43 board ready to go, and the sw30s aligned on paper ready to switch. With tweezers, I gently nudged one of the stock emitters until the moment it felt loose, then I pulled them all off and positioned the sw30s as quickly as possible.
Once the sw30s were positioned as well as I could get them, I killed the heat and move the pan aside to let it cool down before removing the board.
Some fresh Arctic Silver, reattach the wires and….Woot!! It works. A bit rough and ready on the soldering but I’m happier with the beam now. The optic no longer suits it but I’ll worry about that some other day.
Thanks guys. It was a bit nerve-wracking doing the switch over quickly. As I understand it, we don’t want the leds exposed to that heat for more than 30s or so. I think a multi-meter is on the cards at some point so I don’t have to rewire to be able to test. Or maybe a desktop power supply? Hmm, I see how this goes.
Ps. Anyone know if this uses serial or parallel wiring on the board?
glad it worked, here is a more relaxing strategy that works for me:
1. when the stock emitters are off the mcpcb, I remove it from the heat and put it on my silicone soldering mat. I leave the hot plate on.
2. I put a small amount of fresh solder paste on the mcpcb
or if the LED and mcpcb have been reflowed before, I just put flux on the mcpcb
3. place the LEDs on the mcpcb… the paste or flux holds them approximately in place.
I intentionally dont line them up too perfectly
4. Now I move the loaded mcpcb onto the hotplate and watch for the solder to wet, and for the LEDs to move, as they get sucked into alignment on the solder pool
5. to insure good contact, I bump the LED to make sure it rebounds into alignment, and then
6. give the dome of the LED a quick Tap to eject excess solder. (I use the flat handle of my tweezers as a tapping tool)
7. Remove mcpcb from the hotplate and place it back on my silicone mat. (I dont leave it on the hotplate to cool down)
Nice work. My first multiple-emitter reflow also was on the S43 (sw45k) . A flat hotplate is a nice-to-have. The rim of the frying pan is easily touched, and the hot air coming from it is terrible when you work with lead-free solder.
When I reflow an existing MCPCB, I first removed the existing LEDs and then let it cool.
I then apply some soldering paste to the pads and reflow the new LEDs. The soldering paste makes reflowing very easy since it combines solder and soldering paste into one. This is what I use: Mechanic Solder Paste.
Thanks and cheers. I have a tube of solder paste but these guys came off clean so I thought I’d give it a crack using the existing softened solder. Next time I’ll change the procedure :+1:
