I have about 5 dead 12 volt car battery chargers and need some help testing the rectifier and diode cicuitry so I can fix the things. I haven't soldered anything since Heathkit was around 40 years ago. Can any one help me?

Oh yeah, I am just about completely electronically challenged.

 

Rectifiers are also diodes, so this section of the Ebook might help - http://www.allaboutcircuits.com/vol_3/chpt_3/2.html

You may have some SCR's in there, too.

 

HeathKit is still around, God bless'em. If it hadn't been for that laser kit they had in the late '80s, I may have never picked up a soldering iron.