Not sure what a diode is or what it does, more reading coming up for me I guess! I just have the regular charge light in the dash. I think my next call to action will be checking the wiring from front to back. I will probably do this next year when I (hopefully) re-do the interior of the car.

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The diodes are the little black devices to the LHS of the schematic.
The alternator stator has 3 separate windings which generate a 3 phase AC voltage.
The 3 lots of 3 diodes do a full wave rectification of this voltage and output a wave form of suitable voltage and shape to charge the 12VDC battery.
The Voltage Regulator is the dashed box at the RHS of the schematic.
If any one or more of those diodes is kaput then the voltage generated by that group will be down.

I hope you are paying attention and learning a lot

There is a test at the end of the week

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Regards, Graeme
Just trying to help...
http://nissanman.shutterfly.com/
graemes@internode.on.net

Pretty much but increasing the idle mightn't be the best/easiest way.

An alternators output can kick in at various speeds but most start to put out power at around 1000-1500rpm (not crank rpm).
They also put out more current (amps) the faster they spin up until a point. (Google "bosch alternator performance curves)
At idle (low rpm) your alternator is making very little current.
Reading back to the start of this thread you seem to have alot of electrical accessory load (ewp, ecu, lights, fuel pump, thermo, battery, etc).
This is probably too much of a current draw when at idle for your alternator to supply.

I'd now try one of the following:
-get a bigger alternator that puts out more current at the same idle rpm.
-put a smaller pulley on your current alt to make the guts spin faster at idle therefore producing more current.
-like you said, raise your idle like factory setups do when you turn on your a/c...

Smaller pulley might be an option. One thing I noticed is that the pulley is actually two pieces, I wonder if there are any other cars that use that setup with a smaller diameter?

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Bumping this thread up. So I found another RB30 alternator for sale for a steal, which is only a few months old, so I thought I'd snap it up and give this another shot. No more alternators after this, I promise! Problem is, when I got home I noticed a couple of differences.

Firstly it only has one mounting leg on the bottom, not two, which isn't a big deal since I'll be transferring the internals into my CA20 casing again (unless this one fits as-is for some reason, which would be nice). Secondly, there is no negative terminal on the back. Usually 1 of the 4 screws that hold the two casings together is a bit longer an protrudes further out of the back of the casing, and that's where you hook the negative loom up to, but this one doesn't have that, all 4 screws finish just proud of flush with the casing. Is this one of those single-wire alternators I've heard about, just needs a positive source and that's it?

Do I..

a) use one of my longer screws from another alternator and safely hook up my negative loom to it?
b) forget about my negative loom and just run the B+ and voltage reg?

Sincerely, your friend,
anth-20 questions-510.

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Anth, I've used the voltage reg from my FJ alternator. I don't have a factory light on the dash like you, and the other pin on the RB reg is for the exciter wire. Bosch alternators need a 3-5w globe to excite the unit (which is only an alternator light anyway! I have a small wedge globe tucked up behind the dash). Luckily my current bracket used on old FJ unit still worked for the RB alternator.

Couple of questions;

1. what size belt have you used? saves me going back n forth from parts shop. Currently have a 775

2. can someone tell me how to run the exciter wire (heat shrinked spade terminal in pic) to D+, as well as continuing to use the capacitor (which is also on D+)? Need the capacitor for FM quality.

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1600 with FJ20 & Simmons. something different.

Yeah I know all about the dash light/exciter wire, learnt that from this very thread! My query is more about earthing.

Not sure the exact size of my alternator belt, but remember I made custom mounts so it might be different to yours. Just get a piece of rope and make it the size you need, then take that with you when you buy a belt. Make sure the size is okay for you to slip it on and off without needing to unbolt the alternator.

As for your wiring, check out the pic in my first post (right hand side of image) that shows how my FJ alt was wired up. The exciter wire goes to D+, the capacitor goes from B+ to earth (which I can see is on the right hand side of your first image). So the actual capacitor unit is on the earthed thread and then the wire coming off it goes to B+ with a ring terminal.

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Okay so reading about 'one wire alternators' online, it seems they are self-grounding through the mounts but it doesn't hurt to add extra grounds, so I'll just replace one of the casing screws with a longer one and re-connect my ground circuit. Will report back with updates

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capacitor to B+, job all done

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1600 with FJ20 & Simmons. something different.

BTW, should be around 12.8 - 14v. Having a 12v system loaded, or unloaded with a constant 14v is unrealistic. Especially considering the age of the car and it's associated electrical system.

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1600 with FJ20 & Simmons. something different.