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Joined: Sep 2021
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Grease Monkey
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Grease Monkey
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Hello. My 1936 suddenly started blowing the fuse at the ammeter when headlights are turned on.. I replaced it with another 20a and again, then a 25a and now a 30a is in there. However this is what I noticed with a 25a in it. Lights on, nice, bright, then I heard a click or something, the headlights dimmed, then the fuse went out.

So that's how it all began.

My ammeter needle has always been jumpy, but also it would go up to almost 20 at times. I looked into adjusting the 3rd brush, ran it to the RPM's and checked, using the gage, not a multi-meter.

Things were pretty dirty, so I cleaned all the connections, check the brushes, spring tension.

NOW what happens is, I cannot adjust the 3rd brush. the ammeter shows about 8 amps at idle, but once I get the revs up the cut out points open,,, no charge. the generator is charging, I've polarized it, I even swapped in another delco-remy cut out. same thing

It's almost like the cut out is working the opposite way?

So taking all that into consideration,,, I have no idea what's going on.

It charged before I moved the 3rd brush, and no matter where I put it, this happens.

Thanks in advance.

Last edited by kimo90808; 11/23/22 05:13 PM.

1935 1/2t truck EB, 1936 1/2t Panel FB, 1950 Styline Deluxe Wagon, 1954 Bel Air Sport Coupe
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first check the rubber coated wires inside the head light body. The rubber will be dried up and chipping of. Or could be the head lamp or tail lamp wireing at another location. DO NOT start foolowing around with the generator.


Gene Schneider
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Grease Monkey
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Grease Monkey
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Wiring is all new. That tail light design was archaic, filled it with another lights internals. I'll have a look at all of them though.

The only thing I failed to mention was the high beam switch. Lights only come on in one position, high or low,
I don't know? I've pulled it but that's it, haven't even checked it yet.

Oh I already been messing with that generator. Amazing how just moving the 3rd brush, cleaning the connections, changed things.

Last edited by kimo90808; 11/23/22 06:06 PM.

1935 1/2t truck EB, 1936 1/2t Panel FB, 1950 Styline Deluxe Wagon, 1954 Bel Air Sport Coupe
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Thy are cheap and redially availabl,,,,I would just replace the switch.


Gene Schneider
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Grease Monkey
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Grease Monkey
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Yeah, I checked all the lights they're all good. it hasn't burned a fuse. 30amp now though, which, on another post you mentioned that should be fine.

Now back to the generator

Charge at idle, maybe 6 - 7v, as I rev it up before it gets to 2000 rpm it'll go up to maybe 15 then straight to zero. stays there for a second when I go back to idle, then back to 6 - 7, and repeat.

I've watched the cut out, it opens at the higher R's. Isn't this opposite what it's supposed to do?

Thanks Gene, I always know if it's an answer from you it's a solid one!

Last edited by kimo90808; 11/23/22 08:40 PM.

1935 1/2t truck EB, 1936 1/2t Panel FB, 1950 Styline Deluxe Wagon, 1954 Bel Air Sport Coupe
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At idle speed, aroud 400 RPM, the generator should not be charging anything because the contacts in the cut-out relay should be open, If you speed up the engine so the genertor is producing more amps the points should close. They should also be open when the engine is not running or it will drain the battery.
You can check this out by remover the cut-out cover.


Gene Schneider
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Grease Monkey
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Grease Monkey
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I've been watching it, but when the points close the ammeter goes to zero. OK well, I've isolated the lights to not be the problem, I really don't know what caused the fuses to blow, and it looks like the generator is off to the rebuild shop. Generator charging problems kill me. Thanks!!!!


1935 1/2t truck EB, 1936 1/2t Panel FB, 1950 Styline Deluxe Wagon, 1954 Bel Air Sport Coupe
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The generator or the cut-out will not cause a fuse to blow.


Gene Schneider
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I had a similar problem and traced it to the dimmer switch.


1936 GMC T-14 low cab. TA for 1935-37 GMC, Director of the Gulf Coast Region
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Grease Monkey
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Grease Monkey
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OK! Yeah the switch seemed to be the problem with the fuse. But I'm still having problems with my generator, or the cut out relay. and a very shaky ammeter needle.

At idle the needle is just above zero. when I rev it a little the needle goes up to near 20, I rev it more and then it goes back to zero, while still revving, I let off, back to idle, and the needle then goes just above zero again.

all I did was clean the wire connections on the cut out, the generator and the brushes, then after installation attempted to adjust the 3rd brush.

The ammeter needle has always been shaky

I intend to take my generator to my guy, so I guess my next question is, and should maybe be my next search, is why is the needle so shky and is it normal, and, what does a bad ammeter do?


1935 1/2t truck EB, 1936 1/2t Panel FB, 1950 Styline Deluxe Wagon, 1954 Bel Air Sport Coupe
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Oil Can Mechanic
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Oil Can Mechanic
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A rough or oval commutator can cause that. It is a good idea to take the generator to someone that does generators.


J Franklin
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Just a precaution: when you take your generator to a shop for refurbishing, tell them to NOT take off the name plate and DO NOT paint over it.

Sadly, I did not realize this when I took my '28 generator to a local shop. They did good work on the generator, but the nameplate was painted over and I could not remove their paint and still keep the original painted information on the plate.

Dean

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Grease Monkey
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Grease Monkey
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OK thanks guys. Unfortunately the data plate is already gone. I'm lucky to have a local generator guy that not only specializes in them and alternators but is a classic car enthusiast himself. Dean, there's a gentle paint stripper I've used in a spray can, perhaps you know about it but it worked on a few things for me, "goof off", I was able to save the original markings on a WWII helmet that had been painted over several times. Thanks again !!

Last edited by kimo90808; 11/27/22 09:00 PM.

1935 1/2t truck EB, 1936 1/2t Panel FB, 1950 Styline Deluxe Wagon, 1954 Bel Air Sport Coupe

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