Topic: Stator Coil Outups 0 volts ac, faulty stator coil?

[yarburdin]

Hello Everyone,

Honda CB 750 k7 here.

My battery is not charging.

Did all possible tests found on website.

Passed all of them, except couple (will be numbered bellow).

While testing alternator:
 Passed: .6 ohms measured between phases (3 yellow wires) for stator coil, no short on case
 Passed: 7.2 ohms measured between green and white wires on field coil, no short on case
1. While running bike and with 3 yellow wires disconnected, I get 0 vac between yellow wires

Also, the isolation of wires coming from the stator coil melted.
Found this:

2. The white wire coming from the regulator outputs .2V
Are we dealing with the burnt stator coil and possibly faulty regulator?

Attached pics of stator and field coils, as well as the burnt wires coming from the stator coil.

What do you guys think?

[69cb750]

The dark color at the connector is common for older bikes.
1) Check if the filed coil is energized (+12 volts) with bike running.
2) Check output of field coil (ac on volt meter) with bike running.

[scottly]

2. The white wire coming from the regulator outputs .2V

The white wire from the regulator should have 12V with the key on, engine not running. If the field coil is not energized, there can be no output from the stator.
When the field is energized, there will be a strong magnetic attraction at the heads of the mounting screws.
 

[bryanj]

I'm getting fed up of saying this

FIELD AND STATOR COILS ALMOST NEVER GO BAD

[yarburdin]

Thank you all for the comments.

Yes, I've bypassed regulator, powering field coil directly from the battery.

The field coil created magnetism on the cover, and the stator coil outputted desired 15-20 volts ac.

The problem is that its my second RegulatorRectifier (RR), meaning that something else is wrong with the charging system.

The story goes as follows:

PO said the battery was not keeping the charge.
I got a new battery but a different model with polarities swapped.
Didnt look while installing, toasted main harness for few secs and probably burnt most of electrics on the bike.
At that point brought the bike to mechanic, described the situation.
The guy said he inspected the harness across the bike and fixed burnt parts of the wires. Suggested to get new RR, since the battery was not charging.
Got the bike back, got RR unit, installed, but the charging issue didnt go away.
Checked alternator - passed the tests.
Flipped out; ordered new wire harness, installed, and vuala! - start getting 13.5 - 14.5 V on the battery while revving the throttle.
Rode for a month, than the problem came right back - the battery is not charging.
Just now figured out that the regulator went bad again.

Couple side notes: PO changed the ignition key switch for some cheap chinese one (mechanic told) and my rear light is not working (trying to think of everything).

Afraid if Ill change RR again, it will go bad soon.

But maybe I got a #$%*ty RR in first place (paid $30), and I should of gotten a $120 piece.

Any thoughts?

[tlbranth]

I'm getting fed up of saying this

FIELD AND STATOR COILS ALMOST NEVER GO BAD

I'm with you Bryan. On this forum and the Naked Goldwing forum people are always chucking stators to fix what is probably a bad connection. The power connectors on both bikes are inadequate. I replaced mine with Anderson Powerpoles.