Update report:
All test performed successfully, and according to plan.
Connector located, opened, didn't look bad, good in fact, but cleaned thoroughly anyway. Re-inserted several times, and retested charge performance. Little to no improvement.
Disconnect again, and measured the resistance of all three generator coils. All within spec, and all bang on equal. Phew!
Run engine, to high revs, and measure all three AC voltages, pin to pin. Well in excess of 60V at 5000 rpm, and all about equal. Not possible to say if identical, because of fluctuation of steady rpm, but all three similar, and well high enough. Double phew!
Disconnect battery, and perform all diode tests, on the rectifier, as shown in the table previously, but all away from the regulator, at the end of long wiring looms, as I suggested might be possible above. All read a tad higher than spec, which did not surprise me, with the extra wire involved, but all read in the correct region, and matched each other where they should. Also, all were the high values, when meant to be high, and the low values when meant to be low. To my mind, the diodes were all behaving perfectly, at this low test voltage, thus, most likely, confirming that the rectifier portion of the rectifier/regulator is operating within spec. Of course, you can't test how those diodes behave under the much higher AC voltages from the coils, at high rpm, but in my mind they passed this low voltage diode test perfectly well.
What the manual never mentions, is how the regulator itself can be checked. Personally I don't think it can be checked. The diagram I showed earlier, shows an array of diodes, which I assume will perform the rectification, but the regulator, unmarked, is just a mystery black box. If, whatever is in there, is failing, how can that be checked properly?
Knowing that it passed all the prescribed tests to this point, I put it back together, and performed the charge voltage test again, and confirmed something that I'd noticed last time, but was wanting to check it for sure, before reporting it fully here. When I rev up, the more I rev up, the lower the output gets. To my mind, it should go higher and higher, within controlled limits, and get to, or above, 13.5V and stay there. Indeed, since it's meant to be regulated, it should soon be at 13.5V, with just a few revs, and stay there, all the way up to 5000 rpm.
Mine did the following. Lights on high beam, at idle, 13V and slowly climbing. Revved it up, and as it ramped up to 5000 rpm, the charge voltage dropped and dropped and dropped, until it read 12.75V, which is well below spec. On letting it go back to idle, it soon climbed back to above 13V, and continued it's very slow climb. So it could charge at low revs, but was loading the battery, and causing drain, at high revs, when the coils were definitely outputting a much higher AC voltage, because I'd already checked that. So, to me, it actually looks as though it's overregulating as the output from the coils increases. Maybe this is common for whatever is inside of the mystery box, when it's beginning to fail, who knows?
Either way, that points to poor regulation, to me.
The other thing, that pointed to lack of regulation, to me, is that the lights flicker a little, at lower revs. If being regulated well, the voltage should be steady, wouldn't you think?
I realise I have to get both the rectifier and regulator, since they are in the same package, but I'm fairly sure these two outcomes point to the regulator itself, and I need a new rectifier/regulator, despite the fact that it actually passed all the tests described above, apart from the actual charge rate test itself.
Would you guys agree that it seems likely to be failing, or might there be something I've overlooked. Of course I've not checked it at the regulator itself, but if the wiring or the connector there were dodgy, my diode tests would have been way out, and they were not.
Cheers
Sutty
