Test of Rectifier Regulator of Royal Enfield Motorcycle

Rectifier/Regulator is one piece unit in Royal Enfield motorcycle. It receives current from alternator as AC, converts it to DC, regulates voltage and safely charges the battery. It is located on down tube of frame below gas tank in G5 and under headlight, behind name plate in C5. In some models, it is under the seat. Its diodes are tested with digital multimeter (DMM).

[@whorayful]

As you have already worked out, it's the series pass element of the regulator that stops you getting any reading on the red lead. Another simple go/no go test is to measure between each of the yellow leads, you should measure twice the reading (two diode voltage drops) each way between each lead. If any lead measures 'open' or shorted the rectifier is dead. Note, some cheapo multimeters may not be able to measure two diodes in series, quality meters like Fluke, Snap On and others should manage ok.

[@hariharanc6251]

Nice bgm & good explian

[@hari-317]

Interesting video and problem. I feel the rectifier is a three phase "half wave" rectifier type instead of the three phase bridge rectifier normally found. Thus there is no continuity found in the diode test mode between the alternator inputs and the negative output. For this system to work and the circuit to be closed, the alternator must be of star winding type with the neutral grounded (the negative terminal of the battery is also grounded to the bike chassis, so the circuit gets closed without the need for the 4th wire i.e. neutral to be run from the alternator stator to the R/R unit).
Pls do the following test to determine if the alternator is indeed of the grounded neutral type: With the multimeter In the ohms mode with the range set to say 400ohms, measure the resistance between the body of the motorcycle (say the clutch cover) and the alternator terminals. If the neutral is there and is grounded, all the three alternator terminals will show nearly the same resistance to the motorcycle body and this theory maybe confirmed. If the alternator is three pgase type with the neutral disconnected then the terminals will show "open" with respect to the bike chassis.