Dead Short - Seems to be in the Rectifier

[ray forsyth]

Took the CBX out this morning. An hour later stuck on the roadside with a blown main fuse. disconnected the Red/White, Green, Black connector (Red/White and Green go to the rectifier, Black goes to ignition) and got going again with spare main fuse.



At home I checked the alternator/Stator resistance: .5ohm vs manual spec of .4ohm and White to Black 35 ohm (no specs in manual);



All Yellows to Green and to Red/White at the rectifier 4 to 5 meg ohm in both directions (way out of spec -manual says 5-40ohm forward and 2 meg reverse);



Red/white to Green at rectifier .3ohm - almost a dead short; ohm's law says that draws 40 amps through a 20 amp fuse - no wonder!



Everything I read on rectifier/voltage regulator/alternator problems result in a benign failure. Mine is catastrophic.



I am charging up the battery before I can check the voltage regulator.



Any ideas??



Thanks in advance,



Ray Forsyth

[Ray Forsyth]

What I did not ask in my previous post, but which is surely the most important part: why has it gone wrong?



This is a '79 CBX and the rectifier is the original (judging from the condition of the component), so why now?



Ray Forsyth.

[ukchap11]

Have you looked at the alternator clutch plates to see if they are scored? My 82 had a similar problem and after putting a new regulator the bike still was not charging, now after digging deeper, the plates had formed a groove and were not doing the job of keeping a charge?