Triple not working - anyone spot check my setup?

I accidentally overheated a board while struggling to get the wires soldered onto it, the LED slid sideways and came off.

D’oh.

Eventually I cleaned everything off, looked at another emitter to make sure which way was up, laid the board on top of a something or other
C-shaped like a bit of split copper pipe with a flat end
figuring the heat would belong right under the emitter but would spread out, and the C-shaped bit of metal might protect the rest of the board.

Stuck the soldering iron underneath where the emitter ought to be
Nudged the emitter gently to exactly where it ought to be
Kept the heat on
It sort of wiggled and laid down flat.

I pulled the heat off and stared at it for a few seconds wondering if the solder had turned solid yet.

Realized it had.

Lifted the star away with pliers and set it on a flat piece of metal.
And started blowing on the thing like crazy for a while to cool it off.

Then I more carefully cleaned off the wire positions and soldered them and tried it.

Lit right up.

You’d be surprised. Heck, you might be astonished.

PS — it’d have been smarter to do this on a throwaway emitter and board from my trash bin.
But I always figured I’d never get it right the first time and wasn’t ready for the long painful learning curve.

Well, well …

The board is pretty clearly labeled. S~~, S+ and P+, P~~ with an exclamation to highlight it. This sort of gerrymandering is necessary with series/parallel combo boards. All you need to reflow is a hot plate or cooktop and the lid from a tin can or a pan. Either that or sever the traces to isolate that led and add wire jumpers to power it.

Thanks for the suggestion. But I have an induction hob and my girlfriend would kill me I used a frying pan (non stick) for this kind of thing.

Ok, have watched a couple of YouTube vids and gave it a go with the soldering iron.

Led came off, rotated it and it appears to be soldered back on. However it still doesn’t work.

I measure 7.8’ish volts coming from the driver on the ± wires on the star.

You have tinned the solder pads of the jumpers but not been bridged. Add more solder to connect the pads.

Sorry, I am wrong. Connection in series don’t need the jumpers.

Read the whole thread. He bought this with the jumpers on, set up for parallel. That’s why there is solder on those pads. He took the jumpers off so he could use it in series. Bridging those pads is not going to help. :wink:

Edit: You caught it before I did. :bigsmile:

7.8’ish volts? With the LED’s in series, shouldn’t you have around 10v to turn them on?

The driver instruction page says

Clear as mud…

do you use 3 or 4 cells in series to power that thing?

Using 2 x 26650, as I was under the understanding that should work. I was recommended this driver for this setup in a previous thread.

Driver spec says:

“Operating voltage:3-18V”

Should I be doing something different to get this to work. At this stage I’ve got myself completely confused with series and parallel in regard to what voltage will be sent to each led vs current.

the driver can’t put out enough voltage to run this setup in series unless you add another battery. If a third battery is not an option, then the bottom right emitter needs to be flipped back around and the jumpers need be put back on to make a parallel configuration. It then will work

I think this is no boost driver!

rebuilding to parallel should bring the light…

Assuming that the led’s are ok and all soldered joints have connection there is only one reason for it not to work, the star that is.
A short, double check that where you removed the jumpers has no solder left to bridge the gap, the top (in the pic) one looks like it is bridged.

Cheers David

I know I might get my hand into fire by replying but the current setup is nothing, neither parallel neither series because the jumpers are removed. Edit: I was looking at the OP image


Soldering the jumpers back will make the connection in parallel if you have not switched the position of the LEDs.
Or switching the polarity of the lower right LED without having jumpers soldered will make the configuration in series. Careful with the wire inputs where are soldered.


That driver claims that it is boosting right, then you need less input voltage than output voltage, very clearly, again if it is a boost driver.

"Automatically buck: single lithium or double-lithium can promote 3-4XML boost,"
This of course makes no sense. Buck is not boost, Boost is not buck simple as day an night. But still one could try to deduce that inputting 2 cells should makes the driver be able to run 3-4 LEDs in series.

I agree your emitters are properly installed now for a series setup but a couple of other things come to mind.

This would be easier if I could mark up your photo but I’m not sure how so here goes, all comments relative to your photo in post 48.

Confirm the jumper pads closest to the + pad are not bridged, hard to tell from the photo.

You mention 7.8ish V from the driver, I assume that’s a dynamic measurement on the + and - wires. Match’s graph “(here)”:More Emitter Test Results (xpg2, xpe2, mtg2) Updated 11-12-12 shows forward voltage of the XP-G2 starting at 2.8V (for only 200mA). I think your available voltage is too low.
I would do a voltage drop across each emitter to confirm. Use a DVOM, first + probe to red wire from driver, - probe to pad at 2:00 in the photo. Second, + probe to 2:00 pad, - probe to P+ marked pad just below center in the photo. Last + probe to P+ pad just below center, - probe to - wire from driver.

If I’m not mistaken, for a 2.8A driver you should be seeing approximately 3.0-3.1V per LED or 9.9V across the driver wires.

But then again I may be out in left field.

Good luck with it.

Also, if by any chance you may find a low value resistor (the value of the resistor is not so critical, let’s say minimum 10 ohms up to 100 ohms), in that case you actually will be able to do some simple tests in order to decide what was wrong there.
The resistor must be used to bypass each of the LEDs, one by one.
During the tests if the two remaining LEDs lights up, for all the three situations, than we have a low voltage converter.
If not all the three combinations will produce results, then maybe there’s a LEDs problem in the circuit.

Configuration for series in this image is good, I was looking at the OP image when I wrote my last post, sorry about that.

Thanks for the tip.

As I say, I’m getting confused here. If I change it parallel with 2 x 26650, won’t that be 8.4v to each led? Fine for a single li-ion setup, but not for a double li-ion? Or should the driver buck this down once there is ‘load’ on the system?

I’m also confused about what config will result in what current to each led. I was lead to believe this driver would supply 2.6amp to each LED while running from 2 x li-ion.

See my post was edited to make the first sentence i wrote irrelevant, again I was looking at the photo in the OP.

No I am not saying that you need the jumpers for either connection.

But your current setup is correct.