MOTOROLA Alternator redux

The 1970 Motorola was exactly the same with one exception - they changed the brush cover to a metal plate with the ground connection.
Instead of the phenolic brush cover and the ground going to the negative internal diode stud, the ground now went to a spade or flat type connection next to the field/brush connection.
1970 also saw a change in model numbering as Motorola dropped the OEM model numbering - no more "A12NAMxxxxx" - they went to a more universal model numbering and the auto makers chose from those. Saved a bunch of money.
So 1970 model year would have a model "8ALxxxxxx" instead of "A12NAMxxxxx" and would have the ground next to the brush or field connection instead of on a stud on the back of the alternator.
As long as it has the isolation diode and does NOT have a diode trio, it would work with 1970 and prior regulators.

Now I have seen some fools take and put an isolation diode on a 71 and later Motorola thinking gee, this alternator is missing a part -

Look in the back of the alternator through the rear vent holes.
Each diode INSIDE should have ONE wire soldered onto it.
Of the diodes on the left (with brushes on top) have two wires to them, it should NOT have the isolation diode, the red plate, on the back.

So if you hold the alternator, looking at the back, brushes on the top, all diodes inside should have ONE wire soldered to each diode - that's for 1970 and earlier.
If you hold it looking at the back with the brushes/brush plate at the top and the diodes on the left (positive diodes) have TWO wires, that is a 1971 or later and MUST NOT have an isolation diode on it.
the second wire to each of the three positive diodes is the diode trio inside the alternator that takes the place of the isolation diode.
Do not run both.

In other words, don't run an isolation diode on an alternator with two wires soldered to the positive diodes inside as it has a diode trio inside.

Note - one wire on each of these diodes for 1970 and earlier years. TWO wires on any of these means 1971 and later only and it must not have an isolation diode if there are two wires on these.

Edited by billd - Jun/22/2018 at 1:46pm

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White70JavelinSST Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Aug/08/2012 Location: Minnesota Status: Offline Points: 4867	Post Options Post Reply Quote White70JavelinSST Report Post Thanks(0) Quote Reply Topic: MOTOROLA Alternator redux Posted: Jun/22/2018 at 11:46am
	I have a later version 55 AMP Motorola (I assume it's later than 1970 manufacture) with the red heat sink Diode trio, it needs a cleanup rebuild, Will this work with the 70 voltage regulator? Are there differences in connections on this alternator versus the 70 Javelin 55 amp Alternator ? Thanks Edited by White70JavelinSST - Jun/22/2018 at 11:49am
	70 Javelin SST, second owner, purchased 1972

billd Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894	Post Options Post Reply Quote billd Report Post Thanks(1) Quote Reply Posted: Jun/22/2018 at 1:38pm
	The 1970 Motorola was exactly the same with one exception - they changed the brush cover to a metal plate with the ground connection. Instead of the phenolic brush cover and the ground going to the negative internal diode stud, the ground now went to a spade or flat type connection next to the field/brush connection. 1970 also saw a change in model numbering as Motorola dropped the OEM model numbering - no more "A12NAMxxxxx" - they went to a more universal model numbering and the auto makers chose from those. Saved a bunch of money. So 1970 model year would have a model "8ALxxxxxx" instead of "A12NAMxxxxx" and would have the ground next to the brush or field connection instead of on a stud on the back of the alternator. As long as it has the isolation diode and does NOT have a diode trio, it would work with 1970 and prior regulators. Now I have seen some fools take and put an isolation diode on a 71 and later Motorola thinking gee, this alternator is missing a part - Look in the back of the alternator through the rear vent holes. Each diode INSIDE should have ONE wire soldered onto it. Of the diodes on the left (with brushes on top) have two wires to them, it should NOT have the isolation diode, the red plate, on the back. So if you hold the alternator, looking at the back, brushes on the top, all diodes inside should have ONE wire soldered to each diode - that's for 1970 and earlier. If you hold it looking at the back with the brushes/brush plate at the top and the diodes on the left (positive diodes) have TWO wires, that is a 1971 or later and MUST NOT have an isolation diode on it. the second wire to each of the three positive diodes is the diode trio inside the alternator that takes the place of the isolation diode. Do not run both. In other words, don't run an isolation diode on an alternator with two wires soldered to the positive diodes inside as it has a diode trio inside. Note - one wire on each of these diodes for 1970 and earlier years. TWO wires on any of these means 1971 and later only and it must not have an isolation diode if there are two wires on these. Edited by billd - Jun/22/2018 at 1:46pm
	http://theamcpages.com http://antique-engines.com

White70JavelinSST Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Aug/08/2012 Location: Minnesota Status: Offline Points: 4867	Post Options Post Reply Quote White70JavelinSST Report Post Thanks(0) Quote Reply Posted: Jun/22/2018 at 1:52pm
	Thanks billd.
	70 Javelin SST, second owner, purchased 1972