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sixshooter- the modern combined rec/reg usits are only partially testable off of the bike. You can test the diodes in the rectifier. To test the regulator output, it needs to be on a running motor where you can test the output of the battery charge lead. You can che3ck the output by checking the voltage from the battery charge lead to ground.

To check the diodes in the rectifier involves actually doing 12 different tests on the unit's leads. Without starting a discussion on whether electricity flows from + to - or the other way, this is what you need to do:

The terminals that you need to identify are the three stator leads, call them S1, S2 and S3. The ground terminal for the unit. And the battery charge lead (BCL).

Set the meter to the ohm setting to check resistance. You can also use the diode setting to check for continuity. I like to use the resistance setting because you can check the manual for the unit and find out what the correct resistance readings should be.

With the red probe from the multimeter on the ground, and the black probe on s1, s2, and s3, you should get a reading. Check the manual for the unit to see if it is in spec.

Reverse the leads and put the red on s1, s2, and s3 and the black on the ground and you should get an open line reading. there should be no continuity.

To check the output side, red lead to s1,s2, and s3 and black to the BCL should get a reading. Again, check the manual for the proper resistance.

Reverse the leads and put black on s1, s2, and s3 and thhe red on the BCL and you should have no continuity, or and open line.

If the resistance is out of spec, get another unit. If you have a reading where you should have an open line, get another unit.

If with the bike running it is putting out over 15vdc, get another unit.



chopperfreak and 74rat- My understanding is that some of the excess voltage is dumped to ground, but on an electromagnet system like this, the primary way that a solid state unit is going to control the voltage is by shutting down the field coil thereby actually stopping the charging process. It does this hundreds of times a second to keep the actual voltage produced down to a reasonable level. Anything left over is dumped to ground. A good unit should never put out over 15v. That is not to say that there are not old bikes out there that can do it. That doesn't mean that it is working the way it was intended. Old technology is very forgiving. Can you imagine what a voltage spike like that would do to a modern fuel injection or cdi unit?