1. The overall package was heavier than usual. Must be all that copper goodness.
2. The spring deformation is about what expected: barely any for the large spring, the usual stuff for the small spring.
I got my LEDs today. I had two MCPCBs laying around. One brand new, and one was used before.
The LED I reflowed on the new MCPCB is fine, but the one on the used MCPCB didn’t work. I tried reflowing it a few more times. I used a copper braid to clean as much solder as possible from the old MCPCB and applied new solder paste. Still nothing. I tried a second LED and no dice. Third, same.
The odds I have three bad LEDs are pretty slim, so logic tells me the MCPCB has to be the problem, even though checking continuity with a multimeter works fine.
I can’t get the pads on the MCPCB back to being copper colored, no matter how much I tried they are still tinned. They test fine for continuity but I’ve reflowed to this board like 10 times now across three LEDs and it’s not working.
I have some more MCPCBs on the slow rowboat from china, when those arrive hopefully I’ll find out that using a new MCPCB will do the trick.
For now it’s beer time.
The LED I did manage to get reflowed went into my S2+ with a 7135x8 nangj 105c running a customized version of Gchart’s Babka firmware. Still greenish on low, but the higher settings look much better than the one that came in this S2 from Simon.
I actually tested 1/10 SST-20s to check if every one of them were working, and everything did.
That’s actually why it took me a week to start shipping out the LEDs: additional QA is required, since bad LEDs could spell disaster for me and others.
I’ll take some pictures when it gets dark here. How do you test bare LEDs? I attempted to test two of them by holding the LED in tweezers and using one of the alligator clips on my helping hands to hold the tweezers, then touching the pads with my multimeter. I couldn’t get it to light up, but it’s a crappy test setup so that’s probably it.
I can’t get photos to represent what my eyes see. Maybe I’ll work on that and post some later.
I’ve attempted many times to reflow 4 of these LEDs to the one MCPCB I have left. The MCPCB checks out perfectly with a multimeter, there’s continuity between the three pads to where it’s supposed to be. I’ve cleaned up the pads countless times and retried and retried.
Solder paste, place LED with notch towards negative like the datasheet says, wait for it to flow, bouncy bouncy LED, tap to eject excess solder. Remove heat, wait for it to cool, check with multimeter, zilch, no light. I keep checking another LED I have with the meter to make sure it’ll light it up and it does. I used Matt’s video as a guide when I did 5 LH351Ds a couple months ago and they all worked without a hitch. My troubleshooting brain says the MCPCB has to be the problem since it’s the common element and it was used once before, however it passes every test I can think of.
After reflowing I’ve checked for shorts and nothing.
This is driving me stupid since it has no reason not to work, yet it still doesn’t. Has anyone had a once used MCPCB just not take a reflow no matter what?
I only opened one strip of 5 LEDs. The other is still wrapped in tape, and I’m going to leave it that way until I get my brand new MCPCBs from the slow boat.
This is making me remember when I tried to reflow on the Astrolux S42 MCPCB at one point.
It just wouldn’t work.
It never did work, until the person I sold it to got the same LEDs working fine…
I really hope it’s not the LEDs that are DOA, as it would cost me a pretty penny to get them replaced, and then I would have to get refunded from the supplier.
I mean, I actually sampled some LEDs, and they worked fine. Crushed them with my foot in their packaging, and all of them worked fine and lit up.
I mean, others have received their LEDs and are working fine, which has me worried a lot.
I tend to get obsessively worked up over stuff due to ADHD. I just need to wait for my new MCPCBs to arrive and try again.
The LEDs didn’t appear to be damaged in shipping. They were wrapped in a metric ton of tape.
I’ve only done 6 working reflows in my life at this point, so I’m still a noob. It’s entirely possible that even though I think I’m doing everything right that I’ve still managed to screw something up.
The datasheet shows the little black dot on the same side as the anode, which for connecting LED’s should be positive.
There’s something to do with basic electronic theory such that anode denotes a positive terminal in some cases and negative in others. I don’t understand it, but several online sources say LED’s should be connected with the anode to positive.
Try swapping your power supply leads to the PCB and see if you get light.
Right, on the top of the LED the dot in the corner is positive. But on the bottom pads the notch in the center pad is the negative (cathode) side. I have one working, and I’ve been trying subsequent reflows just like I did the first one that worked.
Did you try testing each LED by sticking your probes into the solder overflow areas on the sides of the emitter pads instead of the wire connection points?