I just got a Convoy S3 with an sst40 led, and was trying different tir lens, and after putting everything back the way it came, the light no longer turns on. Found that if I press down on the led, it will light up. Can I just touch a hot soldering iron on the 2 sides of the led where the the pads are to reflow the solder and fix the poor connection? Or do I have to remove the board and desolder the LED and resolder it to the board? Was hoping for something simple as my small electronics soldering isn’t very good.
Also, just to make sure I’m doing it right, when installing a tir from the Convoy store, I remove the reflector and the plastic gasket that sits around the LED, and install the tir and keep the glass lens in place? I had tried initially with the plastic gasket in place, but that didn’t work so I just set the tir inside the reflector and removed the glass lens to try them out.
Double check that it’s not the wires that are poorly connected.
If it really is the emitter then you need to heat it from underneath to reflow it.
Desolder the wires, remove the board, and toss it in a pan on the stove. Cook it until the solder flows, boop the emitter, remove from heat, and enjoy.
The solder already there just needs to reflow, so you don’t really need to remove the emitter and put it back.
Also are the TIRs you got the ones meant for XM-L sized emitters or XP? The SST40 is the same size as an XM-L.
Yeah, normally you just put the optic directly on the board without the centering gasket that is used for reflectors. I’ve never had the S3 but I think it’s the same pill and reflector so heightwise it should fit fine that way. You can adjust the depth of the pill a little bit if need be.
I don’t think you can just touch from the top side and get any reflowing going on…an iron that would be able to shoot that much heat will proably toast the emitter being right next to it like that (a lot of heat will be sucked into the copper board and usually into the brass pill as well even if they’re a bit loose (not compressed from installation)). I’d remove the pill, desolder the wires, and try reflowing in a pan or with gentle heat from a flame below the board. You don’t want more than 300F and actually a lot less is better…and be quick about it. Too much heat or too long at high temps can easily damage emitters even with tougher ones like this SST. Put a little flux around the sides of the emitter before you start heating…when it sizzles you’ll know you’re getting close and it’s a good idea to have it as a helper anyway. Hopefully that does the trick and if not you can order a new emitter either mounted or bare for not much money.
Pretty sure its not the wires, if I only press down on the emitter itself it turns on. Also, I get a voltage reading when touching my multimeter probes to edges of the LED pads when the light is not working but switched on.
I will probably use a soldering iron on the backside, will have to double check with wifey if we have any previously non stick pans I can repurpose. I didn’t want to remove the board because I’m not good with soldering on circuit boards, but I will try.
When you desolder the wires, do you wick away / solder sucker the old stuff and use new solder going back together? or just heat and remove wire, then reheat to reattach? I’ll have to watch some soldering tutorials, and buy some thermal paste.
Yes, I am using TIRs for 5050 LEDs (with 4 little feet on the bottom) for this light. I did buy a 519a S3 as well, and have the 3535 TIRs for that one.
I don’t think the S3 has a pill. Has a bezel on the top you can unscrew to change the lens, reflector and access to the emitter board.
I will have to buy a infrared thermometer then, been meaning to buy one for work. I watched a reflow tutorial, they put the emitter board on a cold electric skillet and heated to 400f. Is 300f enough?
Nothing to lose. It’s not board work so much really, just the two wires that come up from the driver (through the holes in the pill) and connect to the top of the copper mcpcb there by the emitter. Then heat up the copper and see if the emitter will reflow and behave. There’s no need to remove the old solder…a little new flux is all you need. You can if you want but it’s not necessary here. The new flux is a good idea, though (paste or liquid, either way, just make sure it’s a simple electronics flux and not any typical plumbing stuff). Thermal paste…anything will do really, even the cheap free white stuff that comes with various devices (if you have a computer shop or know an IT guy they may have a pile of the little throwaway packets and give you some).
Here’s an old build thread on the S3…should be pretty much the same except for a different driver in yours. Oh…you’ll want some snap ring pliers with fairly small tips to do the retaining ring. If you have some stout pointy tweezers you don’t care about, you can spread and bend those a little and that’s usually ok…or grind cheap needle nose plier tips. Somewhat important to have a decent grip on the little holes in the ring…don’t want to slip out under pressure and damage the driver board or any components that might be on that bottom side of it.
Oh…sorry…I didn’t know that one had a shelf instead of a pill now. Ignore that part then.
With fresh solder/first flow, 400F (200C ish) will get things moving assuming the eutectic 63/37 leaded solder…often takes a little more heat, though, just depends on how things are. Try to keep the Hot time less than a minute or so and just a couple-few minutes to heat up beforehand…pull it when the emitter sticks/centers and let it cool naturally (can set it on a heat sink if you want, just don’t cool it rapidly). With lead-free solder you need a lot more heat especially with rework. But with both of these, the flux is absolutely your friend…can’t say that enough.
When I did the pan method, I had an old cheap wok (sorta) with a flat bottom…put a 1/4" chunk of aluminum plate in there as a buffer, and figured out where my electric range would get the temp in the zone. But whatever works. You might want to experiment a little by putting some solder in the pan and just observing when it melts, before you try with your board/emitter.
Yes, I tried that, I’m now wondering if that’s what caused the problem. I double checked and the LED doesn’t turn on if I press down on the edges next to the dome, it only turns on if I touch the dome. I think maybe when I was trying different TIRs without the reflector to center them, maybe when one started a little crooked it pushed on it?
Seems like I’ll have to buy another LED or just a board with the LED attached.
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