I know a real test of this unit would be to mount it and run, checking DC and AC voltage, current etc. The plan is to mount it on my Super Dexta, but this would need some work as there's currently a dynamo which is starting to fail. I was given the alternator free and would like to bench test it before I bother to do the conversion. Denso A127 alternator. It was removed from a JCB wheel digger as not charging. So far, I have done the following tests: Regulator: Hooked up to bench power supply, then connected 12V bulb across brushes. Checked bulb glows as voltage rises to 12V, then goes out at 14.3V. I say the reg is OK. Plenty of brush left. Rectifier: Desoldered and checked the six diodes with multimeter diode test, forward and reverse. There is also a component labelled 'DIDE' which has four connections - one to each phase and one to the +ve supply to the regulator - I assume this is a diode pack for 'bootstrapping' the regulator. There is a 0.5V drop between each of the phase connections and the output to the reg. Rotor: Cleaned slip rings - in good nick - and checked resistance between - 3 ohms. No short to body. OK? Stator: Desoldered three (double) phase wires from rectifier, then separated the three pairs of wires. Checked each of the six wires had continuity to only one other. No short to case. No visible damage. The only thing I found 'wrong' was the slip rings being dirty - the digger had sat for a while. As far as I can see, the alternator checks out OK, pending a dynamic test on the tractor. Am I right?