Dual field alternator questions.....

[Staxbro]

Hi, I have a dual feed 1970 on alternator in my '68 Charger.
Was running and charging for many years with the original mechanical field regulator.
As part of a rewire of the car, I replaced the field reg for an electronic version of the same "square box unit" from YO.
Car now starts and runs perfectly, but getting no charge. It only ever had one of the field connectors with green wire, and I have replicated this. With the electronic Field Reg, do I have to connect a second field wire?

If some one is grounded the second field terminal so it can run on a mechanical one wire system, how can I tell?

Confused by this and concerned about potential for fire!
Any help gratefully received. 

[Nacho-RT74]

on earliers system the green wire was regulated positive and the only wire arriving to the brushes, while the other brush was grounded to chassis.

on later systems, both fields are now wired and both brushes are isolated, BUT the green wire becomes on regulated NEGATIVE source, while the other brush needs to be sourced now with constant positive coming from ign switch blue wire network.

I guess if you had dual field alt on mthe mech reg, is because one of the brushes was grounded somehow.

BE CAREFULL now and check for that, being sure BOTH brushes are correctly isolated, because if you accidentally plug the blue wire to the grounded brush, will get a short burning the wire from end to end

[John_Kunkel]

If some one is grounded the second field terminal so it can run on a mechanical one wire system, how can I tell?

An ohm meter, with one lead on the field terminal and the other on the alternator case or a circuit tester light with one lead on battery (+) and the other on the field terminal.

If the system ever worked with the mechanical regulator, one field had to be grounded...either with an external wire or internally with an early grounded brush holder.

[Nacho-RT74]

Or the field prong isolator washer replaced with a metallic one.

The ground should be visible

[Nacho-RT74]

an early grounded brush holder.

actually, earliers brushes never got a holder, they were attached straight to a casted provision for the brush

But definitelly, if worked with a mech regulator, some of the brushes was grounded AND you got luck didn't shorted the blue wire to that one

[Staxbro]

Thanks all. I will have a good look at the alternator, see what is going on with the grounding and probably post some pics. I thought that buying an electronic updated version of the field regulator would be a smart upgrade. Seems I would have been better getting a reproduction mechanical one!

[Nacho-RT74]

ok, wait a minute... dunno why I thought you upgraded to the stock laters electronic regulator... you got the upgraded electronic on the old version then.

if so, it should work the same than your old unit!... you need a grounded brush to get the constant negative field, and the green wire will carry the positive source coming from regulator

[Staxbro]

Thanks folks.

So I have checked the terminals, and indeed one of them is grounded. Can't see anything visible like a washer grounding it to the casing, so it must be internal, which of course it would have to be to work with the mech voltage reg.

Nacho - just to be sure, before I connect the field wire to the ungrounded terminal, you mean that it should be ok if it is an electronic version of the old style (pre 1970) Voltage Reg (rectangular box type, identical in appearance to the original?)

The year One Part number is RX343, if that helps..

[Nacho-RT74]

Maybe not internal, but the isolation was slightly trimmed to seat the screw straight against the prong without the isolation washer.

Yes, well,  it should, just be sure never connect the green regulator wire to the grounded brush. I'd recommend to cut or bend the grounded prong to make it impossible by mistake, because if some mistake, will get a short.

[Staxbro]

That sounds like a wise plan, Nacho. Hopefully I will get her charging again and then I'll make the grounded terminal safe.
Thanks for the help and advice, everyone.
N

[Staxbro]

Well,
still got no charge.

Have identified the grounded terminal and isolated it. Connected my field wire to the other one and still getting 12.8v at the battery with the engine running. (it rises slightly to 12.9 at high revs)
I've checked the wiring from the alternator to the ammeter and back to the battery and it is all good.

I can only suspect the new solid state voltage reg.

Before I order a new one from the US and wait 3 weeks for it, Am I definitely ok with the solid state version of the "old style" regulator?

Thinking I may be better off ordering an original mechanical one...

Thanks for advice in advance!
N

[Staxbro]

Just had a thought....
If I have inadvertently connected the field wire to the grounded terminal on the alt- will I have just fried my new electronic regulator? I'm guessing while the body is grounded to the bulkhead, the terminals shouldn't be.....?

[Pete in NH]

Unfortunately, it's very likely you did.

[Staxbro]

So this is how my (new) electronic Voltage Reg looked after being accidentally grounded.
I fixed up my old mechanical VR and it is now pumping out a solid 14.4-14.8v.

The chip on the field connectors obviously blew. So take care of shorting to ground, folks!

[Nacho-RT74]

It is actually a transistor, and SHOULD BE cheap and easy to replace. Hoping no other damage allong the circuit. Weird! There are actually weaker components there than the transistor itself