Pulsing Alternator Output!?

[stimps]

Alternator light is on, pulsing, checked battery, alternator still seems to be charging, battery voltage is 13.9 while driving, but car has random shutdowns, very small intermittent ones. Noticed that at 2000rpm reving motor alternator light pulses quicky, upon reving engine up to 4000rpm, pulsing slows down and alterntor output pulses! even with the headlights on and you can see the voltage pulsing in the lights!! weird!

anyone seen this? I am tempted to just buy a brand new aftermarket alternator. Battery is ok. I even doubled up another battery to it and had the same thing happening. Attached an oscilloscope to it and saw a sinewave fluctuating 1 volt up and down at high revs! so as the engine speeds up, the pulsing slows down!!!??

WIERD. anyone have any idea whats wrong? I know I cant buy a new regulator for the alternator so think i have to buy a whole new alterator. A month ago i even had the alternator out of the car and it all checked out ok!?

cheers

car is a import R32 RB20DET manual. 93 model.

Edited March 2, 2010 by stimps

[stimps]

Also just wondering what other skyline R32 owners have done in the past, with crook alternators, whether anyone has successfully changed the regulator in the existing unit, or have had to buy a second hand one, or part with 400 odd bux and buy a brand new item. *shudder*

[MrStabby]

Probably a stuffed capacitor, if i remember how rectifiers work. NFI on why the pulsing slows as revs rise. The rectifier is probably built into the regulator unit....but i got my rebuilt ($380 including everything) so they must be available.

[stimps]

Probably a stuffed capacitor, if i remember how rectifiers work. NFI on why the pulsing slows as revs rise. The rectifier is probably built into the regulator unit....but i got my rebuilt ($380 including everything) so they must be available.

Yeah I think the rectifier may be stuffed, acording to a technician I talked to about it at work. Im taking the unit out tonite and pulling it apart. Your alternator must have been different to mine as Ive searched high and low for a replacement regulator with no luck. Will post my findings tomorrow.

[stimps]

Found an open circiut Regulator diode inside it ( its one of the three little black ones) and changed it. I will put it in the car tonite.

Yeah I think the rectifier may be stuffed, acording to a technician I talked to about it at work. Im taking the unit out tonite and pulling it apart. Your alternator must have been different to mine as Ive searched high and low for a replacement regulator with no luck. Will post my findings tomorrow.

[**RB2530**]

You probably already know this but your alternator output will never be pure DC (even with a perfectly operating alternator)...There will always be some ripple component due to the fact alternator generates 3PH AC that is rectified by simple power diodes..

Good luck with it anyway and I hope you get it sorted...