It could be because of damaged stator winding of simply a faulty AVR ,,,,,,,,,,first check for stator winding ,,,,,,, it can be damaged because of loose armature bearing ,,,,,,,,, bearing become loose in its hub and armature grinds with stator ,,,,,,,,,,, hope so that’s not the case ,,,,,,,,,,, lets consider the second case ,,,,,,,,, before replacing the AVR you must check the voltage of stator connections ,,,,,,,,,,,remove all the connections of AVR and remove it ,,,,,,,, hold a digital multi tester and start the engine ,,,,,,,, now check the voltage coming out from the carbon brushes connectors,,,,,,,,,,, it must be around 3-4 Volt AC ,,,,,,,, if you are getting that then move to next step,,,,,,,,, now gave a 12 Volt DC input to these carbon brushes connectors ,,,,,,,,,,, and measure the current from a 4 pin connector which is coming out from a stator main winding ,,,,,,,,, 2 yellow wires connections are called exciting in mechanics language ,,,,,,,, color may be different but these wires further connects with the 2 yellow wires of AVR ,,,,,,,,,,, without 12V DC input supplied to armature it must be 2-3 Volt AC ,,,,,,,,,and with 12 V DC it must be around 30-40 Volt AC ,,,,,,,,,,,, if you pass this then move to third step,,,,,,,,,,,, remaining 2 connections of 4 pin connector which is coming out from main stator ,,,,,,,, they also further goes into the AVR ,,,,,,,,they are called center loop in mechanics language ,,,,,,,,,,,,,with 12 Volt DC supplied to armature stator it must be around 8 to 9 Volt ,,,,,,,,,,,,,,, if you pass this then move to 4[SUP]th[/SUP] test ,,,,,,,,,,now you have to check the main 220 Volt AC voltage of generator ,,,,,,,,,,,, with 12 Volt DC connected with armature carbon brushes it must be around 100 to 150 Volt ,,,,,,,,,,, if all that ok then replace the AVR ,,,,,,,,, I try to mention these connections on pic , do check that ,,,,,,,,,
