cb77 alternator

[bikedoctor99]

Hello Cadman,
Thanks for clarifying the diagnostics for me.
Checked the stator today:
1. yellow + pink= 0.0acv
2. yellow + brown= 26.5avcv
3. brown + pink= 26.5acv

I found my spare stator Saturday and also installed it with the very same results.
Does this mean that the stator is cooked?
Yikes, sounds like total loss for now.
Allan

[cadman]

Where are you testing - at the plug down by the case or at the rectifier?

Well after your email I re-looked - The instructions I gave you were for a standard three wire alternator. After looking again at the wiring diagram and the diagrams I made it appears your testing may be okay. There are six coils in the stator it appears that all six are tied together and end up in the brown wire (it now becomes a common wire for all 6 coils). The yellow wire then taps into 2 coils for the rectifier (yellow) and 4 coils (Pink wire) for the headlight "on" condition. The bottom line is it seems that brown to yellow or pink should read voltage and yellow to pink would not. Exactly what you found. The fact that a second stator reads the same almost confirms that. I am about 90% sure this is correct. Maybe someone else can add to that.

It looks like that I was probably incorrect.

[bikedoctor99]

Cadman,
Hmmmm----
Thanks for going to the extremes that you have, looks like i've opened a can of beastly worms.
Sooo--- maybe both alternators are ok after all.
When the bike died, I checked for volts at the battery with lights on and off.
The lack of increased voltage made me think that the bridge rectifier was n.g.

I swopped to a new Radio Shack bridge rectifier spare with the same results.
Its entirely possible that the second one is also bad.

looks like I'll stick to my bicycle for the next several days.
BTW the testing was all done at the case.
Allan

[cadman]

Might check the plug at the case and the wires from there to the rectifier. Generally I would recommend getting rid of the plug at the case and soldering the wires together. This is a fairly typical mod on older motorcycles.

[e3steve]

Hello Cadman,
Thanks for clarifying the diagnostics for me.
Checked the stator today:
1. yellow + pink= 0.0acv
2. yellow + brown= 26.5avcv
3. brown + pink= 26.5acv

I found my spare stator Saturday and also installed it with the very same results.
Does this mean that the stator is cooked?
Yikes, sounds like total loss for now.
Allan

Judging by those ACV readings I'd say your stator is ok. Seems to me your rec has pooped its panties. Here's my colour wiring diagram; the colours make it easier to follow.

Here's a tutorial on rectifiers. A fair bit was early, incorrect assumptions but the thread straightens out in the end!

Hope this all helps with some basic understanding.

G'luck!