How to test RR38

[mortonc]

I bought myself a new RR38 a short while ago but I'm not sure if it is working.

I have it off the bike and want to test if it is broken, I have seen a number of different explanations for how to test reg recs so not sure which I should use.

Could anybody guide me with where to begin.

Here is a diagram of how it looks.

 

[BBS360]

Easiest to test in the bike.
If the voltage across the battery rises to around 14V as you increase the RPMs the regulator is good.
There's always the razor blade test. With the bike ignition on the magnetic field from the alternator's field coil should be able to hold a razor blade against the alternator case.
Not a comprehensive test but a quick indicator.
No magnetic field, no charging.

 

[mortonc]

Given that my electrics are all in bits at the moment, do you know of anyway to do it off the bike?

 

[BBS360]

As long as it doesn't need the 3-phase rectifier input for the regulator to function you should be able to do it with a variable voltage power supply capable of doing at least 5-20VDC, a load (the field coil itself would be best if it's off the bike), and a multimeter to monitor voltage and/or DC current.

I'd have to double-check the wiring diagram later but with the field coil wired in and power supplied you should be able to see the current through the field coil vary as the supplied voltage varies.
Supply at ~15V and you should see very little or no current through the field coil.
Drop the supply slowly and the field coil current should increase to compensate.