When an alternator dies what actually has failed ?

[3barboost]

Hi all

When a round plug (early models) alternator fails - what has actually "died" ? is it a simple and obvious thing like a burnt diode ? circuit board melted ? brushes stuck or worn out ?

My alternator no longer charges and they are fairly scarce on the ground this end of the world - any ideas what other toyota models fit ? I dont want to mess too much with pulleys and there spacing etc - the wiring can be redone

thanks for the help !

[Lextreme]

http://www.lextreme.com/alternator.html IC Regulator is the most common problem and contacts would be the next.

[3barboost]

is the IC repairable ?

and what alternator fits from other toyotas ?

[Lextreme]

I think Supras alternators are very similar. Here is an article that might help. http://www.lextreme.com/Lexus-Alternator.html

[Muzza_NZ]

It is very easy to replace the IC regulator if the brushes and rectifier diodes are in good condition. The IC reg is a standard Nippon Denso (ND) part (common to most of their alternators) and readily available. If you type the part number into google, you'll find they're about $30USD direct from China.

Many honda and other Toyotas that use ND alternators have the same reg. Just check their output voltage rating (once again a google search) and excitation current rating.

[3barboost]

Ok I pulled the alt off and decided to have a look see

I found the commutator had worn through the copper to an insulated area underneath !

I have never heard / seen of this before

what type of mileage would it take to wear that out ?

I assume that there is no practical means of diy repair ?

[madmont]

Mine is worn like that but not so bad. I recently replaced the regulator which was not working properly. They are as muzza said a ND part and fitted to other alternators as well.