I work on cars for a living so I had some experience with electronic circuits on a macro level. Beyond that I always have tinkered with computers and such. But as far as down and dirty soldering and working with small electronic circuits.... I basically started all that with the pce / tg stuff.
Since you're a mechanic you might get a kick out of this. My last car was a '67 Barracuda fastback. It ran well enough and only needed a little body work and resto but, it had a small wiring problem so, I had this bright (mega dumb) idea that, I'd just undo all of the wiring from the instrument cluster. I ended up disconnecting the entire wiring harness without bothering to take the cluster out of the dash first because I did it all on impulse.
Needless to say, I knew after that that, I'd never be able to turn it into the hot rod that I'd planned to so, I sold it to one of my brother's along with a nice set of rallies for just 1200 and he traded it for an old Coronet.
Okay. Before I got my TG16, I more or less did the same kind of stuff as Black Tiger. Most of what I took apart was 2600 carts and early NES carts that used flat-head screws so, I could clean them easier.
When I was still a kid, I took apart a Transformers Triple Changer (Blitzwing?), put all of the little pieces (must've been over a hundred) in a jar and after a month, I got it out one day and rebuilt it even though I'd forgotten what went where and yes, it still worked.