I remember being 19 and installing a negative ground Audiovox am fm cassette player in my positive ground 62 Jag FHC. (I still have it at 54)
I must have gone through 2 rolls of black electrical tape and 35 fuses, but I eventually got it working long enough to cruise around in. It had this really annoying habit of occasionally blowing a fuse for seemingly no reason. Usually while I was jamming to a fast song.
Eventually I determined it only blew the fuse in the middle of a fast left hand corner.
That had me stumped for weeks until one day it was real quiet as I had the radio turned down while going through a hard corner. I heard the 25 amp fuse blow out hard with a snap, and I looked down at the right time.
My positively grounded key ring in the ignition switch above the radio had some long dangly stuff that if everything was just right, would swing way over from cornering forces and touch the radio knob, blowing the fuse.
It was an Ah HA! moment, but I had also created my very own primitive g-meter.
You could now measure your corning performance by if you blew a fuse, or not.
The game now became; If you didn't blow the fuse, you weren't going fast enough.
The beautiful solution was to simply shorten my key ring.