Yes it is true that you can ground the secondary brush on a 10 SI Delco to make it give full output. The little tab behind the "D" hole grounds the brush lead and causes full output. The rotor is always hot and the regulator just supplies a ground path on a 10 SI. Appling power to a the excite lead on a 10 DN gives the same results.
I really advise against running full loads, especially reverse, through a 10SI diode. At a Delco Remy tech seminar we were shown the results. Picking bits of crap out of your face is not my idea of fun. The Delco service manual has definite warnings against trying that stuff that is done to Motorola units. Delco used six different types of diodes in the ten series. Unless you are real sure of the diode type; leave the high reverse load checking out. The CS type threw in the avalanche diodes and that gets even harier.
There are special units to check diodes, and the rear sub assembly, and they are expensive. I have one on my bench. I did not blow a week's profit for nothing.
10DN (external regulator) Delco can diodes are not the same animal as the button pack type SI units. The parts look similar in some cases, but mixing parts makes the day exciting. The diodes are totally different in both type and use. Type S can diodes will not normally blow while type B can diodes normally pop at similar loads. Button diodes in more modern units, and those Pontiac transition models, are even screwier.
Just hook up the #1 lead to the battery positive post and the #2 wire to a 12volt bulb that is grounded, while the alternator is turning. This will magnetize the rotor and orient the stator. The self exciting units use residual ground to start the turn on cycle. Something must power the rotor magnetic bobbin first. After you excite the unit, you can then plug the hole and it will self excite.
The only difference between a self excite and a regular unit is the tight rotor to stator air gap and the regulator. You can install a self excite regulator in any unit and it behaves normally. With no close air gap; the self turn on does not work and the regulator just behaves like the cheaper OEM type unit.
A short from winding to winding is checked dynamically on a test fixture. In real life, without a high frequency tester, these kinds of shorts always show up as hot windings or pulsing output. They are easy to spot on the final spinup test.
I agree that the old Delcos were the most reliable units ever built. When GM spun off Delco Remy; they also killed off quality alternators too. Now the Delphi units are even crappier than the competition. Delco Remy America had not built anything in years. Delco is now just a name slapped on Korean and Chinese scrap. They subbed out everything to the aftermarket suppliers for years before that. Now that most of the aftermarket is even gone, we are left with nothing.
I hope to be suppling quality Delco Remy parts, through my buisness, soon. Getting supplies set up is getting tricky because I refuse to sell import scrap, with my name on it. Even Echlin (NAPA) has gone the route of cheapo substitution. You might as well just buy the junk because the name brand stuff is just a difference in cardboard boxes.
Charlie Biler
www.molineparts.com