Couple things to try
Thanks very much for the helpful advice. Here's an update:
I crawled under the panel and checked the fuses and wiring to/from the Strobe light switch (BTW, I didn't build the airplane so the switch wiring and harness wiring is a bit confusing, if not a mystery, to say the least). The strobe toggle switch connector wire to the Whelen Power Supply has partially melted: the insulation melted and pooled into a glob around the connector. The now bare copper wire is greenish in tint. It appears to be a case of thin (white) wire coming into the switch from airplane power (battery) and a thicker (red) wire going to the Whelen Power supply - a mismatch in wire gauge leading to overheating at the switch. It's the red wire that's burned outgoing from the switch to the Whelen PS. There's also a 10 amp (red) blade fuse that's blown but I'm not sure what it powers since there are no labels and I can't follow the individual wires to the fuse box because there are too many wires and they're all white. It might be the strobe fuse or not. In terms of solutions to prevent future problems with overheating at the switch, I could replace the thin white (power) wire with a thicker one which would require digging into the wire harness and be a pain because, as you know, you have to invert or contort yourself to redo wiring under/behind the panel. Or maybe install a relay between the switch and the Whelen power supply to serve as a voltage regulator/circuit "policeman." Any comments/advice appreciated since I have a limited understanding of electrical circuits.
I am sure someone with more professional experience wiring will eventually chime in but there are a couple things to check:
First, with the master and strobe switches OFF, check the continuity (with a multimeter) between the load side of the blown fuse and the pole on the strobe switch with the white wire. Assuming you get the beep indicating continuity you know the blown fuse is for the strobes.
2nd, if the red wire is melted then it is almost certainly the problem one. Since the Mil-Spec Tefzel wire normally used is tinned copper, the red wire is probably just Hardware/auto wire. The green tint on the copper wire is corrosion (the mil-spec wire is tinned specifically to prevent corrosion). It’s possible the corrosion developed after the strobes failed but my guess would be the corrosion caused the failure. Corrosion
dramatically increases the resistance in that part of the wire, which would explain why the insulation was melted right there and why the fuse blew.
If there is any excess red wire it MIGHT be possible to cut the corroded bit of the red wire off, strip a bit more insulation off, tin the bare wire and reattach it to the switch. However, I would only do that if someone here with professional electrical experience (which I don’t have
) said it would work long term.
If it were me, I would use the existing red wire to pull a mil-spec m22759/16 16 gauge wire from the switch to the strobe power box. 16 gauge is more than enough for a 10A fuse and 10 ft will cost about $5 from any of the vendors selling wire who advertise here.