Re: 1972 R75/5 charging problem
Posted: Thu Oct 13, 2016 12:05 pm
Andy, Just connect the two blue wires together bypassing the relay. I suggest a good solder joint with heat shrink insulation.
I took the relay apart today, and discovered some corrosion. I also discovered that, due to the way the relay internals are assembled, there's no easy way to access/repair the connection between the two No. 30 terminals. I ended up jumping them externally, by drilling small holes in the base of each terminal and soldering a short piece of solid copper between them. This fixed my charging problems entirely- I now have 14.2 volts to the battery at 3000-4000 rpm.
This was an interesting problem, especially because it did not show up when continuity testing with a multimeter. The corroded connection between the two No. 30 terminals could pass the low voltage of the meter well enough to show decent continuity, but couldn't manage the full output of the charging system.
Thanks again to all who responded with information and ideas!
Andy