Alternator question

[randy]

Hi, guys. Have a question about the alternator. Anyone know the output in AC volts of each phase? At idle, what value should I see between ONE of the white stator wires and ground? I know it should be the same for all three, just don't know the value. Thanks.

Randy

[xs1100yam]

Hi Randy

Normaly nothing between ground and white wire !!! ( or nothing significant...)
If I remember correctly the 3 coils are "floating" regarding ground; the first connection to ground is after the rectifier.
The 3 coils have a common point, but NOT connected to something else.
So the only interesting AC voltage measurement should be between 2 white wires. Of course, the tension should be the same between 1 & 2, 2 & 3, 1 & 3 but I don't know the value : I'm not curious enough

But I should check on my diagram ( tonight when home : actually at work !...) I'll give you more info tomorrow (afternoon for me, morning for you )

Patrick

[Geezer]

I don't know the value but strangely enough the gas guage is powered directly from one of the wires off the stator and I'm assuming there is a diode in between the gas guage and ground.

Geezer

[xs1100yam]

Strange... ...Because in that case, the gas gauge doesn't work with engine stopped
On my diagram ( 78 E 2H9 ) the 3 stator coils are connected to rectifier ( white wires ) and one of the 3 is also connected to tachometer; ( the tachometer showing frequency of AC )

IMHO the voltage between a white wire and ground is due to internal resistor of the corresponding diode

[randy]

OK, Guys, the white wires have to have some potential greater than ground because one of them trips the headlight relay and another (or maybe the same one) signals the tach. Right?

So, what's the voltage at the (white) on the headlight relay supposed to be? It's AC, not DC because it come straight from the stator, as does the white at the tach.

Gee, I'd go test it myself, but I'm 100 mi away from my bike right now. I'm asking because I ran it the other day and the headlight was out. High and Low beams, and the indicators on the tree were out too. So I'm guessing RLU (AGAIN!) or headlight relay. Fuses OK.

PS Thanks a million to Rover for the spare RLU! It worked great. This is a new trouble.

Randy

[CMA1]

Randy,
Check your PM.
Larry

[randy]

OK, guys. Tore into the wiring this morning and here's what I found.

The yellow wire at the headlight realy is fed from the alternator, apparently from a seperate winding inside the stator? Anyway, the reading I got was:

Key on, engine not running = 0 volts

Engine running = 12 volts AC

So it seems my headlight relay is fried. Verified it by jumping the red/yel to the light blue and viola! All lights work, RLU is OK. So i'll ride her this way until I replace the headlight relay. I'm going to replace it with a common automotive 12v relay. That way, the relay will drop out when (if) the engine stalls.

So now you all know. 12v AC pulls in the headlight relay.

HTH someone else,

Randy

[CMA1]

Randy,
I just came in the house... it is 1:00 am.
We have had rain for 2 days here and it is kind'a cool outside (no garage.)Break in the rain so I went out with meter in hand...

I got 0v key on, not running
14.2 v bike running (but your meter is probably better quality than mine.) I said I'd get to it asap.
That H/Light relay can be reworked... I sent you a PM.
Good luck.
Larry