After reflowing my SP36 Pro I seem to have broken it and was hoping someone could help me figure out where I went wrong. When screwing in the battery tube as soon as the battery makes contact the light turns on at a high output and is generally unresponsive to the switch. It will not turn off or ramp, however I suspect the switch is not bad as when I try a factory reset of Anduril the light does respond with a flash after ~4 seconds as expected. I see no damage to the driver, or nicks in the wire sheathing or bridging between the solder where the wires connect to the driver or switch. There is a patch of solder mask that has peeled up by the negative terminal on the MCPCB, but when I test the MCPCB with a multimeter on diode mode the light lights up and shows a voltage of 2.38v. I’m guessing it’s a short but I’m coming up short (if you’ll pardon the pun) on where to look for it. Any help would be appreciated.
It sounds like you have a solder bridge under one or more of the LEDs.
The - is bridged to the center DTP pad.
This causes electricity to flow through the LEDs 100% of the time, as it bypasses the driver.
To verify this remove the wires from the MCPCB and check continuity from - to the copper MCPCB.
There shouldn’t be any continuity as the DTP Pad is supposed to be electrically isolated.
More or less the same answer, just using different words. And more words.
Though I don’t own an SP36, this was the cause of similar behavior in some of my single led flashlights.
The MCPCB’s are usually fed by one or more pairs of leads, coming from the driver. Usually red ones and black ones.
The red lead(s) connects the “+” the on battery(ies) with the “+” on the MCPCB.
The driver does not do anything, the MCPCB just conducts the current from the spring (or knob) on one side of the driver to the red lead on the other side.
The black lead(s) connects the business-end of the driver with the “-” on the MCPCB.
The “-” side of the battery connects via the spring in the tailcap to the body of the flashlight.
The MCPCB connects to the body though the copper “ring” that usually surrounds the MCPCB.
It is imperative that this “ring” is the only thing that connects the MCPCB to the body of the flashlight.
When working on an MCPCB, is can happen that your soldering creates some kind of blob on it.
If that blob touches the underside of the reflector, or other parts of the body, it creates a shunt that bypasses the MCPCB.
Look for big blobs or damaged black leads that can come in contact with parts of the body.
I use a strong sheet of plastic that I cut to size to put over the MCPCB (leave a hole for the led).
Other members use kapton tape. Damaged leads should be replaced.
Thank you both! I tested for continuity and there is continuity from the negative to the core of the board. No blobs or anything causing a bridge that I could see. After discovering the continuity I looked more closely at the negative and it appears that I didn’t just damage the mask, but the substrate under the mask that isolates the core from the electrical paths. As silly as it sounds I’ve never really bothered to understand how mcpcbs work but I think it’s making sense now.
I wonder if it’s possible to re-isolate the core with some epoxy now, or if the board is totally shot. If so does anyone know a source for a new mcpcb for the sp36?