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Discussion Starter #1
hi. i understand that there should be low resistance between the yellow (output) wires of the alternator (single phase) and that there should be very high resistance to earth/chassis from these yellow wires. i have just checked my alternator and i get 60V ac at 3,000 rpm which i think is fine. BUT when i do the resistance check:
  • my yellow wire to yellow wire is less than 10 ohm - which is great
  • my yellow wires to earth/chassis is less than 10 ohm - which i hear is not good
but i get 60v ac? it seems that one of the yellow wires is grounded - does anyone know if this is a problem and why? cheers.
 

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Sounds as if one of the coil winding have shorted to ground. it must be near the end of the winding or a worn spot at the grommet as voltages look to be okay but I do not know for sure. I would look closely at the wires where they come out of the engine case.
 

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yes i think one of the contacts is shorting to earth. my thoughts are that if one of the winding is at earth (0 volt) then the other winding will have to go to a maximum of 60 volt ac and therefore i'll have "2 x voltage" across one of my regulator diodes (and 0v across the other) which means the rectifier part of the regular will get very hot and will fail quickly - and its expensive!

i don't know if the above logic is correct. what do you think? i did say it was techie :)
 
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