Iâm not sure you understand. All versions have the trace go under the spring. That is not an issue. If the sharp (cut end) of the spring is directly over the trace and itâs soldered in such a way that itâs pressing directly against the trace, then a heavy blow might push it through the solder mask and make contact.
Your light in the picture looks fine. I see no chance of the spring ever touching the trace.
Den, Iâm sorry to hear about your lightâs failure. Iâm glad youâre okay and that Neal is taking care of a replacement.
My spring is resting on the board in the area of the trace. A piece of paper wonât fit between the spring and PCB.
With the trace and FW3A label positioned at 6 oâclock, the end of my spring is soldered to the pad directly to the right, between the 4 and 5 oâclock position.
This places the âgapâ between the 1 and 2 oâclock position.
I plan to rotate the spring when I get back to my soldering iron.
I assume (perhaps incorrectly) that springs tend to be installed so that the âendâ is on a pad and connected with solder.
The bigger question is if the trace burned first due to some other reason and the spring was nearby so they got melted together. Or was there current from the spring to the trace?
Negative current from the battery is already flowing up to the driver at all times (same for positive current) so Iâm having trouble unstanding why the trace burned.
This trace basically connects a very weak positive signal from the MCU down the inner tube and across this trace. When you push the button this weak positive signal gets grounded through the vias and to the spring.
So if the spring shorted the trace it should be no different than holding down the button. Iâm pretty sure the MCU limits the signal current to like milliamps.
I canât think of any reason that trace would carry high current, high enough to burn it. The spring touching it should not cause a high current flow.
That appears to be the fault in the one i had short, while the edge of the spring was not directly on the trace, as seen in the photo the spring edge was roughly 110 degrees at roughly 2 oâclock on the board, so the spring was directly resting on the trace. Also i did notice as seen in that photo the spring is only soldered to one of the three solder points, and i could lift the spring up off the board a little as it only had one weak solder point. As seen in the second photo, you can see where the two other solder points were not soldered to the spring at all.
Resistance, the spring only held or making contact on one solder pad. Maybe the srping got hot enough to burn thru the damaged masking after the fall, and the heat from resistance burn the trace? Kind of strange really, unless the driver shifted and made some kind of short? It is strange indeedâŚ
So the bottom end of your spring is soldered at the pad nearest the âFâ in the FW3A label? That allows for the maximum air gap.
Upon closer inspection, my spring has solder on all three pads, but only one is making what Iâd consider a âgoodâ connection. The other two look a bit cold and could use some more solder. Iâll touch everything up when I rotate my spring.
Yours looks like the position of mine. If they had placed the spring cut-end on the 7 oâclock solder pad, then there would be a good 1/2 mm or more gap over that narrow trace. Its an easy fix to rotate the spring as fortunately the switch board is easy to remove from the tail cap.
absolutely thrilling for those of us who are clueless about what you speak of. NOW I feel like I shouldnât handle my flashlight like I normally do. Sheesh!
You guys had me worried a bit with this discussion because the end of my spring sits directly on top of the trace that shorted and I have knocked the light off a 2 drawer file cabinet where it lives no less than a dozen times (likely an underestimate) . Yes I am that clumsy.
Yes there is only one good solder pad holding the spring. But fortunately it is the one to the left of the trace which happens to be holding the end of the spring slightly above the surface and I expect that makes all the difference
@ shirnask âŚ. Those are good clear pictures showing the end of the spring. Thanks for posting!
That should help clear up some of the confusion that was mentioned earlier.
Those are good photos of the example of the spring end being in a place where if impacted enough could âdig throughâ the coatingâ and short through the trace. but in your case as you mentioned, they soldered it with the spring just off the board surface, making yourâs lucky to probably not short in that spot. When min fell, it landed tail-cap down hard on a hardwood floor, making the battery slam down on the spring hard enough to short the trace.