alternator question
 

When I first put the turbocharged engine back in my car it started right up and after a blip of the throttle the red light went out on the dash. It has always required a blip of the throttle ever since i got the alternator rebuilt two years ago.

Anywho, I had to shut the engine off to fix an oil ine. The next time I started up up the red light would no go out. I checked the voltage at the battery, 11.9 volts.
I checked all the fuses, no change. I checked all the electrical connections and ground straps, nothing. Hopefully I didn't jack up the 14 pin connector or something.
I did find one strange plug and I posted a question about it here http://forums.pelicanparts.com/porsche-911-technical-forum/151099-help-identifying-electrical-plug.html#post1192492

The engine runs real good excpt for this problem and I don't want to drive it until I get it fixed.

If it is the alternator I'll pull it, I just want to make sure everything else is OK.
it is on a 1980 SC, does that have an internal or external voltage regulator? In case you haven't noticed I'm a dummy when it comes to spark-tricity.

I found out it is externally regulated. I pulled the regulator and what looks like a ballast resistor or something, they are plugged together. I checked all connections, looks good. I reinstalled except this time I piggy-backed some wires that connect to D+ and DF, and hook the wires to a remote starter button. i started up the car, no charge, then pushed the botton, still no charge. i figure that bridging the D+ and DF should make the alternator go maximum load and charge, but it didn't do anything. I pulled the alternator and checked all wiring, it is wired up right. The only thing I wondered about was the blue wire that is supposed to go to D+ on the back of the alternator goes to +61. There isn't a D+ so I figure that's the same thing. Plus it is wired exactly as it came out and it worked before.

I pulled the brushes, they look good but the slip rings are not perfectly
true. Guess the people who rebuilt it 2 years ago did a mickey mouse job.
I struggled getting the fan off the shaft. I had to tap two of the holes in
the front of the fan to 1/4 20 (being careful not to get any shavings in
places they shouldn't be) and use two bolts and a bearing puller to
carefully pull the fan off the alternator. it worked slick.

Now I guess I have to take the alternator to be tested and or repaired. Sux.
I really wanted to get on the boost today.

Sam,

There are a bunch of threads on this type of thing in the archives that can guide you. But here's my quick and dirty: Voltage at the battery of 11.9 volts tells you the alternator's not putting out current. The red light being on, ditto. So it's down to either the alternator or the regulator. The "ballast resistor" is probably a RFI noise supressor, and you can remove that from the circuit- just carefully plug the voltage regulator and the black connector together.

What you were trying, "Full-fielding" the alternator, would tell you if it was faulty and it might also blow it up. You see, the way the voltage regulator does its thing is to control the current flowing through the DF (dynamo field) circuit. The more current that flows through the DF wire (into the rotor) the stronger the magnetic field created in the rotor, the stronger the field created in the stator, so you get more output from the diodes connected to the stator. When the engine is first started, there is no magnetic field in the rotor- it has to come from somewhere-- and that somewhere is the "Blue wire" circuit, known as D+/61. Current flows out of the battery through the ignition switch, through the warning lamp, and back to the electrical console. It goes to the voltage regulator, and then out of the electrical console through pin #11 of the 14-pin connector you have so carefully avoided messing with (it's delicate). Anyway, the current flows into the rotor, inducing a current, the alternator begins to put out current, and some of that is captured by the voltage regulator and fed back to the rotor through the black wire, the DF circuit, which then fluctuates up and down to keep the output constant.

Clear as mud, right? Anyway, when you jump the DF with +12v, you are faking the alternator into thinking that the engine just started, and you are basically telling the alternator to give you maximum output. But when that happens, the voltmeter will peg at about 18V, and the alternator will cook itself pronto, so shut it off!

If you want to try it again, make sure you hook up the connections right-- blue D+61, brown ground, red B+, black DF, and remove that RFI supressor and try it. Shouldn't take long. If you try the full-field trick, that will tell you whether the VR is bad but be careful, you could fry the altnerator and set the car on fire, no kidding!

Good luck! Hope you get back on boost soon.

This morning i checked all the associated connections on the 14 pin connector to make sure that wasn't my problem, it wasn't.
I took the alternator to the place that rebuilt it two years ago for testing. They said it was bad but couldn't tell me what part was bad. I didn't get to talk directly to the tester, only the person behind the counter.
I'm waiting for a call from the manager as soon as he comes in to work.
Price for rebuild again) is $145, I'm hoping he will work with me in the price. It's always something.
Has anyone here done the upgrade to the internal regulator style alternator? I printed out the service bulletin that describes the procedure, I'm just wondering if it is as straight forward as it looks.

Sam, the upgrade is pretty common. I would not recommend it, particularly because you have a turbo engine. Do a search under my name to see the reasoning behind it.

I'd buy a new regulator also. and carry the old one as a spare.

I just finished reading the archives, seemsmany folks are concerned with the internal regulator getting too hot.

I tend to agree and really didn't want to do it unless my alternator is not rebuildable or reliable. seems like the older external regulated alternators are NLA.

Can anyone explain why the OEM regulator is over $60? I don't get it. Generic regulators are usually in the $20 range. I read that it is important to match the regulator with the alternator but I'm not sure I buy into that. Don't they all do the same thing the same way?
I know on the 914s it is common practice to replace the regulator with a solid state modern version.
Anyone try a generic regulator on a 911 who really understands this stuff? I don't want to try it, just curious. These alternators are too expensive for someone like me to experiment with.