figured i would do some other checking on the 1930 , still need to tweak the tuning

generator output, used my meter to check generator output to battery, per the specs generator spinning at around 1700 rpm (850 engine rpm) should put out around 16A - 8V, with the meter on was getting zero nil nothing from the generator output side, and reading 6.5V from the battery side (which is what i get with meter on battery).

so decided to polarize generator first, just to be safe. turned off, polarized, then fired engine back up to recheck and still nothing.

next up was to pull the cover band off and see where the third brush was sitting. and when i removed the cover, what do i see ??masking tape, old crusty masking tape, looks like whomever painted it masked it off and never remove it when done.

removed masking tape and noticed one of the brush wire insulation was worn off to bare wire and touching the third brush. so pulled off wire put on a layer of heat shrink and reinstalled. also noticed that the third brush would not move as well as springs was not holding it down against armature. yes, screw was loosened first  worked the brush a little but and finally began to move, spring also was fine, but but stuck, so now all moves and spring holds brush against the armature.

put it all back together and set the third brush to 4 bars away from brush.

all back together before adjustments

rear brush

did a test run and still nothing on the generator output.

adjust brush closer as that is supposed to increase output, still nothing, moved further away and still nothing

not getting a single volt or amp coming out ?!?

so anything else i can do, or time to pull and have it rebuilt ??

Now you need to check field coils for continuity and grounding. Can do that with a VOM. Be sure to put paper under the brushes so they don't conduct through the armature while testing the coils. If all tests okay then it is time to take it apart and check armature for shorts, etc.

My guess is it needs to come apart for more detailed and accurate testing and repair.

well dropped of the generator at the local starter/gen shop to evaluate and advise.

are the armatures readily available if needed ?? per my MPPL they list 817221, and looking around online looks like many places listed them for sale from $20 to $50 also reference Lester #733 ?? few NORS but many rewound

anything particular i should look for or avoid ??

Before they work on your unit, make sure they DO NOT paint over the information tag.

Been there and didn't do it. ;-(

Dean

also got another gift today got the generator from the rebuilder. said the armature was fried, so replaced it with a new and also cleaned up the inside.

also put on an aftermarket cut out, but still have the original one as well.

shot a short video of the sparks...

should i put on new brushes, or will the sparks go away once the brushes seat ?? or ??

1930 Chevrolet Universal AD - Generator Rebuild Sparks

If you replace the brushes it is going to do that until they break in. If they aren't showing serious wear, I don't think I would bother. New ones will lose considerable length right away as they wear to match the curve of the commutator. I would drive it and if it is charging OK, leave it alone.

I agree that you do not need new brushes. That extra arcing is due to the slight curvature different between the old brushes and the new commutator.

The old brushes should be bedded in to suit the new radius of the new commutator(it should be in the owners operating manual),otherwise the arcing between the commutator segments & the brush face will cause severe burning of the soft copper segments,causing the copper surface to become abrasive and cause premature brush wear.It can be done in situ,by getting hold of a commutator "bedding" stone,which is essentially a soft friable pumice like material,and hold it against the rotating commutator.As the segments rub against the soft bedding stone,particles of it will break away,get dragged between the brush & commutator surfaces and bed the brushes in to suit the radius of the new commutator.Then just blow the carbon/stone dust out and the jobs done.The bedding stone can also be used to remove any "glaze" that builds up on the segment surfaces causing squeaking brushes.
I did this both as part of my job in a motor winding w/shop at the local steelworks for 34 years as an electrical fitter/mechanic,and re-building starters & generators at home as a hobby.

also went through my spare parts list i made up (been getting spares for the 1929 while engine is in shop), and seen that i have a spare set of Brushes for the 1929 generator, so will be swapping them out and putting in the New set, then seating them using the stone when it arrives in the next day or two.

well decided to look more into the generator before i replace the brushes.

looks like the shop did a 5 minute job on it, basically pulled the cover removed old armature, put in new armature, replaced the cut out with a newer diode style. threw it on the bench and validated it had output.

this is with the engine running about 10-15 minutes.
was hoping they would have at least looked at the bushing, bearing, springs, brushes, wiring and replaced any and all of it, they are easy simple parts all under $5 each !!

gong to talk to them today, but want to validate that the output is adjustable on the generator. at idle the ammeter shows 0, then press on the pedal and it pegs the gauge on the charging side. going to put it on and use my meter to see various output is, if any. gauge is pegged with lights on or off. per my volt meter it is putting out 7.2-7.5V DC on the generator side.

it is installed, belt on, battery connected, as i get 6.x volts on the battery side of the cutout.

can i polarize with this type of cut out ? or will it fry it ??

Sounds like they have the third brush set for way too much charge. That will potentially overheat the windings in the armature to the point that the solder melts.

A good starting point is to set the third brush about 2 commutator bars from the fixed brush. The charging rate is constant and is a function of the third brush setting.

The cutout does not alter the charging rate. It is energized and the circuit closes essentially when the voltage from the generator is greater than the voltage from the battery. There is no voltage or current regulation in a third brush generator system with just a cutout.

Your shop manual or the spec sheet should tell you what the charging rate should be in amps and at what engine speed. Remember that needs to be checked at the output side of the cutout. The ammeter reads the net charge going to the battery. The ammeter reading does not include the current used to energize the generator field coil and the ignition system.

When you check the output specs in the manual also note the variance of a hot vs. cold generator. If my memory serves me right i believe there is quite a difference.

With the original style electro-mechanical cut-out,if all the air gaps and point gaps are set correctly,the voltage needed to close the points should be between 7.0 - 7.5 volts,with is adjustable on the old style cut-out by means of increasing or decreasing the tension on the flat spring steel strip on the top of the cutout.
The position for the maximum safe out put on most 3rd brush generators(at least most GM ones),is no closer than 2 segments away from the + main brush(the one that takes the output to the cut-out).For normal day time driving,a charge rate of a about 4 - amps is more than adequate.The output current must be measured at the generator cutout,as the reading on these primitive ammeters doesn't take into account the ignition current draw.
The 3rd brush is just a very primitive form of current output control,and as you drive the car at increasing car speeds,the output will slowly drop off due to "armature reaction".This "armature reaction",is caused by the magnetic field produced by the wire conductors in the armature winding becoming stronger(depending on 3rd brush position)overcoming the strength of the magnetic strength of the field system,which is an electrical characteristic of any 3rd brush generator.

ok, tinkered with the 3rd brush, did not change or do anything with the generator yet.

used my multimeter and used the amp clamp to clamp the wire from the generator to the cut out. at idle was around 5A, then as i revved up the engine it went over 40A !! which would explain pegging the ammeter on the dash at 20A

my understanding, and per the diagram on Bill's 1931Chevrolet Page, moving he brush away from the front brush, going towards the engine block would decrease the output !! however this increases the output. so i pulled the third brush all the way forward, as close as i can get to the front brush, and output at idle was around 1A, as i revved up it went up to around 4A. so i can have to push it away from the front brush to increase output.

this is complete backwards of the diagram ??

i understand that the output should be around 8-10A at around 1700 rpm or cruising rpm.

The third brush setup is a battery killer.
If you set it to carry the ign load in the daytime, you'll run down the battery when you use the lights.
If you set it to keep up with the nighttime load, you'll overcharge in the daytime.
A diode makes a far better cutout, but doesn't help the regulation problem.
I have heard of solid state replacements for cutouts, but haven't seen anything lately.
I can design one and will try it when my truck is going.
WL

Hi all,

Check out the Filling Station's cutout rebuild with a diode: Filling Station cutout rebuild for 1929-1939 Chevys

Cheers, Dean

Check to see that the lead from the cutout goes to the + main brush(the fixed brush nearest the mudguard),and that the smaller lead from the field coil on the mudguard side of the generator barrel is connected to the adjustable 3rd brush.
If the leads are transposed,the field in effect is connected directly across the armature and no amount of moving the 3rd brush will lower the output,as the generator is trying to work like a "shunt field connected generator".If the output is still not able to be controlled by moving the 3rd brush,it could be that when the armature was re-wound,the lead "throw" to the segments is not correct.

did some more checking this am before calling the shop back.

with the third brush pushed all the way forward, i get the 1A idle 4A running, but as soon as i move it any away, it goes to 10A idle 40-60A running. so something is NOT right.

Are you able to motor the generator? When I tried motoring my rebuilt generator it ran backwards. In my posting at the time I finally resolved the problem.

"Problem finally resolved! I bought a second rebuilt generator on e-bay. When I compared the two I noticed that the field coils on my first generator had been wired backwards. I had replaced the coils with new ones and wired them the same as it was when I got it from the re-builder. The wire which was supposed to go to the field brush was screwed to ground and the one which was supposed to go to ground went to the brush. When I tried to motor the generator it rotated backwards. Re-polarizing didn't change the direction. I switched the wires, and now it seems to be working fine, charging 8-10 amps."

Just one more thing to check.

Will try to motor it this weekend...

talked with the shop and he inquired to validate I have a good solid ground, and then validate cut out is not a lemon.

so i ran a hard ground direct to the generator casing. used one of the bolts on the case/housing. did a few random continuity checks on the generator and have a good solid ground. fired up the engine and checked generator and same ordeal. output does not seem to vary when i move the third brush. so something has to be wrong. or i am missing something.

next i left ground connected and put on one of my 1929 cut outs that i know works. also metered it off the car to validate function before installing. installed and connected on the generator and same thing.

i am going to swap out generators, and see if i install the one from the 1929 on the 1930 what happens, just to eliminate everything outside the generator itself.

I would be looking for a different shop. I am far from being an expert on electrical components but they should be able to diagnose and advise quickly especially since they "rebuilt " it. You should not have to be the one to do all the testing which they should be able to do in less than five minutes.

Hi BearsFan315
It's been a while since I worked with a third brush, but...
Two things.
First
Is your picture posted at #449316 10/23/20 05:57 PM from after it was to the rebuilder?
I ask because that armature has way too much copper between the bars and needs to have it cleaned out. Probably a little undercutting as well.

Second
Is it possible that as you move your third brush further away from your armature output brush, the wire from the third brush to the fields is bare somewhere and is contacting a bare spot between the armature brush and the armature terminal... and then getting full armature voltage?

Just a few thoughts
Good luck!

If there was any copper between the segments,even a minute speck,it would cause the armature to show a short circuit in the winding(if tested correctly on a growler),and there would be no output at all.Sounds like the "re-builder????" needs to go back to basics,and you can't get more basic than a 3rd brush generator

well decided to channel my inner electric mindset... pulled the generator and then chased the circuit flow. also helped that i have the same generator on my bench from my 1929 which is in the engine shop. this generator works great. so can do a side by side. as well as the info provided by CJP's 29 (Thanks)

and what do you know it was a ground problem, one that the rebuilder caused !! the third brush was wired directly to the output wire, runs from brush to the gen side of cutout. this wire is supposed to run from the front stationary brush to the gen side of the cutout. the wire from the field coil is supposed to run to the third brush vs the front stationary brush. i swapped the wires around and then reinstalled, and away we went. i put the third brush all the way up (lowest output) and that is what i got. then pushed it closest to the front stationary brush and got the max output. approx 10A at idle up to 18A then slowly dies back off. I adjusted the brush so that it was putting out about 2-4A according to the dash ammeter, which is approx 6-8A at the cutout according to my hand multimeter. rev up to max output is approx 8A at ammeter. this is all with lights off.

going to look into adjusting the cutout to ensure it is working correctly. i swapped out the electronic one for the old school one for now. wanted to validate it.

nailed it

pulled the generator off and will drop it off in the morning with shop 2 along with a check list and specs, same as i did for shop 1. see what happens

Dropped off generator at shop 2 this morning, with info i had (same as shop 1)
they told me should only be a few days, since they stock most items in house

we'll see what they have to say, wonder IF they will call me BEFORE they do any work, supposed to diagnose and tear down then call me with details and recommendation.

got a call from generator shop 2...

gentleman had finished rebuilding the generator, and was inquiring as to what output i would like it set to. he said it is working great, adjustable output, etc. he inquired as to how i was getting an output from the other armature ? stated it was bad, plus it was NOT the correct one for the generator and that looks like the one end was chewed up in the bushing. they are saving the old parts for me.  he also stated when i come it he will put it on the bench and put it through its paces for me (demonstration).

so kind of excited to go pick it up and see what we have. hoping for a fully functional & operational generator !!

Great news, it sounds like you got good service!

Nice!

went by the gen shop this morning on my way into work and picked up my rebuilt generator. plus got my box of old parts.

generator looks good, will install it and test it out. 

few pictures of the old parts. and the NEW old Armature


original field coil, bearing, brushes, and NEW OLD armature (from other shop)

close up of field coils

armature from other shop

close up on the bushing end of the armature, defined grooves !!

few shots on the rebuilt generator GUTS

brushes have been seated, generator output tested and validated, should be ready to rock and roll....