Re: Diodes Part 2

["Gary Walker" <NashFlash@xxxxxxxxxx>]

   You can run one of these Motorola alternators without the isolation diode
but it is like replacing a fuse with a slug.   The diode mounted in a red
stamped steel heat sink plate on the back side of the alternator is there to
protect the internal diodes which are much harder to replace.  Clip your
jumper cables on backwards and the isolation diode may go, but the circuit
to the internal diodes should then be open and protected.
      Gary Walker

----- Original Message ----- 
From: "Todd Tomason" <jayscore@xxxxxxxxxxxxx>
To: <mail@xxxxxxxxxxxx>
Sent: Sunday, December 12, 2004 10:42 PM
Subject: Re: Diodes


> I've never seen these red diodes on an alternator.  I have come across
them on
> eBay and such.  What years did they use them?  Were they only used for
> certain amperage ratings?  I'm assuming we're talking about the Motorola
> alternators.
>
> Todd
>
> On Sunday 12 December 2004 22:33, Gary Walker wrote:
> >    The isolation diode is the big red one on the outside of the
alternator
> > case.   This may be the only one that is damaged.  You can change it
with
> > the alternator in place.  Inspect it by checking continuity in both
> > directions.  Current should flow in one direction only.  If it is found
to
> > be good, and the output is still not over 14 volts, then clean the
armature
> > where the brushes rub,  Check the brushes for length and free movement,
and
> > if that fails then pull the smaller diodes on the inside and check them
for
> > current flow in one direction.  At this point, go ahead and replace the
> > bearings with new sealed bearings from a local bearing house.  They are
> > very inexpensive.  Some parts houses may still have the diodes.
> >          Your AMC friend,
> >           Gary Walker
>
> >            Owner of some old AMC cars and stuff
>
>