Voltage Regulator Question

[Old Henry]

Just took the generator apart and don't see any connection between the armature circuit and the field circuit which it seems like there would have to be for the generator to charge with no outside current being supplied to the field. Tested the field resistance and it was 3.3 ohms - right in spec. Tested for short between the armature terminal and the body of the generator and there was none.

[Old Henry]

Said the shepherd boy to the little lamb, "Do you see what I see? (Echo: Do you see what I see?) Down there in that hole little lamb?" (Less than three months till Christmas.)



What's wrong with this picture?

See that little wire from the field terminal to the field? It's poking out. And, it's insulating coating is gone and it appears to have gotten hot. When I put the end cap on one of the brush brackets hits that wire and feeds current directly from the armature to the field causing my problem. I'm thinking I'll push the wire down, maybe a piece of tape around it just to be sure, and I should be good to go. (Keeping my fingers crossed.)

Also, notice the silver ring around the inside just next to the field coils? That's the solder that melted out of my old armature when it overheated and killed it.

[Old Henry]

So, I pushed down the offending wire, covered all with tape, put it back together and back in the car and it works perfect, even on the oldest of the three regulators I now have. (Now have two spares that I never wanted.)

I'm pretty excited, I was getting worried that I'd have to put off my Route 66 trip I'm planning in two weeks.



The wire at the bottom of the picture that hooks the two sides of the field together actually had to be brought out away from the side as the bolt wouldn't line up with it next to the side.

[Old Henry]

Originally Posted by Old Henry

I can only guess that somehow the output has shorted to the field circuit and it is feeding the field from the output and making it charge to max the same as in the open circuit voltage test koates previously described in #9.

Originally Posted by koates

. . . if the generator is still charging flat out with that field wire disconnected then there is a short or incorrect connection in the field circuit inside the generator. Pull gen off and open up and recheck what was done when you replaced the brushes. Check the two field wires where they are connected and get back to me. Regards, Kevin.

We were both right on! So much for local generator "experts" that could only say, "That can not happen. It just doesn't work that way."

[Old Henry]

What I learned from my experience and the advice of others:

1. Votage regulators are not the cause of charging problems as much as I used to think. (Evidence me now owning three perfectly good ones.)

2. Generator brushes don't last forever. Then do, in deed, wear out and have to be replaced.

3. Be careful when changing them to check the field wire and make sure it's pushed down and to the side so it doesn't touch the brush bracket when the end is put back on.

4. There is almost always someone on the barn that knows more than me from whom I can learn who is willing to help and teach.

[Old Henry]

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I have thought more about the source and cause of my problem since, when I replaced the brushes, I never touched that field wire. I've concluded that when my generator was built by the company I bought it from that wire was touching the brush bracket but the insulating coating on the wire was preventing current from passing from the brush bracket into it until I changed the brushes. Then, when putting the end cap back on, I twisted it back and forth just a bit to line the cap up with the case. That scraped the insulating coating off of the wire so that contact could be made and cause my problem. Do you think?

[PeteVS]

I think that when the generator was originally built, there was one continuous length of wire through both field coils. The stretch between the two coil probably had a short piece of some sort of insulating tubing for protection. Then, your generator was rebuilt somewhere along the way and one half of the field coils was replaced. the wire was spliced and gently tucked out of the way. That's my opinion. (By the way, one indication that the generator has been "redone" is the oxide colored paint on the inside. There's over spray on the coils and the paint is down into the rust pits on the inside.)

PS: Just looked at the pix again and you can see the remnants of the insulating sleeve where the connecting wire emerges from the coils.

PPS: You might want to consider putting some sort of insulating sleeve over the through bolt that passes that splice. (Plastic straw? Or unshrunk heat shrink tubing?)

PPPS: Also, try to get that piece of tape (on the right side of your after photo) trimmed back and tucked down to avoid it coming in contact with the armature and breaking the wire or something like that.

[Old Henry]

Originally Posted by PeteVS

I think that when the generator was originally built, there was one continuous length of wire through both field coils. The stretch between the two coil probably had a short piece of some sort of insulating tubing for protection. Then, your generator was rebuilt somewhere along the way and one half of the field coils was replaced. the wire was spliced and gently tucked out of the way. That's my opinion. (By the way, one indication that the generator has been "redone" is the oxide colored paint on the inside. There's over spray on the coils and the paint is down into the rust pits on the inside.)

PS: Just looked at the pix again and you can see the remnants of the insulating sleeve where the connecting wire emerges from the coils.

PPS: You might want to consider putting some sort of insulating sleeve over the through bolt that passes that splice. (Plastic straw? Or unshrunk heat shrink tubing?)

PPPS: Also, try to get that piece of tape (on the right side of your after photo) trimmed back and tucked down to avoid it coming in contact with the armature and breaking the wire or something like that.

''

All good points and ideas. I did rearrange that tape on the right so as not to touch the armature.

Thanks.

[Roger/Sacramento]

In certain situations I have used the Liquid Black Tape to cover a connection. It hardens up and provides a solid coverage.

[koates]

Hi Old Henry, you have done very well to sort your problem. It just goes to show that one must be verv fussy when assembling equipment during rebuilds. Pete VS is correct when he states that the field coil wires usually have sleeving on them when built new, but some dont and rely on the enamel coating for insulation. I usually fit some insulation sleeving around the through bolt where the field coil link wire loopes around the bolt. You should check the current regulator maximum setting (30 amps is enough) as l described in an earlier post. What a shame it is so difficult to find a good old auto electrician theese days. Your man should have picked up this fault when he test ran your gen in his test bench. One test we always do in the test bench is disconnect the field terminal wire on the generator whilst running to make sure the field is not internally shorted like yours was. He stuffed up. As they say, " hard to find good help theese days ". Regards, Kevin.

[PeteVS]

One last point... You stated that the errant field coil wire / splice was touching the brush bracket when the rebuild was done. If that was so, it would have never worked right. It most likely moved around with the vibration and temperature swings the generator witnessed. (As I recall, your generator has seen some temperature swings?)

[rotorwrench]

The materials used for insulation back in the day left a lot to be desired. They didn't have vinyl (PVC) to any great extent. Pyroxylin coated cotton fabric was more common. The stuff will fall appart if you touch it after 40 or 50 years of existence.

[Old Henry]

Now that the generator is working fine I need to figure out how to adjust the regulator so it lets the generator put out more when I'm driving at night with the lights, radio, and heater running. Sadly, the last "expert" to work on my generator had no way to hook it up to a regulator to test it. The generator is not keeping up when I know it has the capacity after seeing what it will do with full current to the field. Will test all voltage and ampre outputs to see if they are at spec and adjust if not and if are will adjust anyway to get more out of the generator. Any ideas on that are welcome.

[Mart]

My personal experience is that any regulator I have tried to adjust ends up being thrown away. I think it may just be me. Glad you found the problem with the generator, though, that's good.

Mart.

[Old Henry]

Originally Posted by Mart

My personal experience is that any regulator I have tried to adjust ends up being thrown away. I think it may just be me. Glad you found the problem with the generator, though, that's good.

Mart.

Yeah. I've heard they are pretty tricky to adjust. I guess it's a good thing I have three of them if I'm going to try that.

[Old Henry]

Just checked the voltage output between the armature and ground terminals on the regulator and it was 7.1 - right in the specs of 6.9 to 7.2. So, guess I don't need to adjust that.

Hoping to borrow my neighbor's amp meter tonight to test the amp output.

[PeteVS]

You want it to be charging at 7.2 (7.1 is fine) at both no load and high load (Hi beam head lights and heater motor) at a high idle. If you tweek the springs to get that, make sure the readings are the same when you put the cover back on. I was taught to never mess with the cut out contacts.

[Old Henry]

Originally Posted by PeteVS

You want it to be charging at 7.2 (7.1 is fine) at both no load and high load (Hi beam head lights and heater motor) at a high idle. If you tweek the springs to get that, make sure the readings are the same when you put the cover back on. I was taught to never mess with the cut out contacts.

How about the current limiting relay in the middle? That's the one I'm thinking of tweeking to get more amps on a cold night.

[PeteVS]

When I was doing this kind of work back in my teens (fifty some years ago) I never learned what that relay did or what to do with it. I was just told that it was the "high load" contact. It does make sense though that it might be a current limiting contact that would open when the load gets up there. When you get hold of an amp meter, let us know what you find out. (Sears used to sell a neat little current meter that one just held over a wire and it would show what the current was in it. There were two sort of brackets on the back side. The larger one was held over a battery cable to read starter current and the other over a generator (or alternator) cable to show charging rate. Haven't seen one for sale in years. I'll have to google for one.)

[Old Henry]

Here is the schmatics of the charging system that shows how current to the field of the generator can be cut off by the voltage regulating relay (on the end by the armature terminal), the current regulating relay in the middle, or the cut out relay on the other end by the battery terminal.