1. What is it?
A Christmas jumper with a circuit of lights in it.
It has a battery box that takes two CR2032 batteries, giving juice of 6v, connected by a JST connector(?) to the circuit that runs through the jumper.
The lights in the jumper don't come on.
Checked that the connector was seated properly. It was.
Tried with a new set of CR2032 batteries. No difference.
Tested the batteries with a multimeter. Showing 3.34 volts, so all good.
Tried checking the continuity of the output from the battery box. Nothing coming out, but maybe just can't make a connection with the multimeter properly.
Done a bit more probing with the continuity tester. Great tool. Basically one of the wires from the battery box isn't working. The crimp looks fine, so it must be a loose connection in the wire itself? Which seems a bit strange, but honestly that what it looks like.
Could replace that wire, but I don't have the tool for redoing the crimp. Probably easier to just buy a battery box.
I decided to trim out the middle bit, solder in a replacement wire, and put some heat shrink on.
So… the battery pack now works. Turn it on and… only the first light comes on! Bah humbug.
I cut a hole in the inner lining of the jumper, and it turns out that the wires seems to have come loose connecting to one of the lights.