Starter generator problems
 

I'm making a new thread after my previous one about putting an ammeter on my 70, i thought everything was running well but the problem has recurred.
This started after I rebuilt the starter generator and it started overheating. Enough that it started peeling paint on the bearing cover and its too hot to hold my hand on it.
After a ton of troubleshooting I thought it was fixed but its doing it again. To eliminate any other issues I disconnected the wires coming off the field winding and the small wire off the armature, just the heavy starter cable. It turns over the engine fine, plenty of starting torque.
After running for more than 20 seconds the generator body starts heating up.
I got an armature growler and it didnt show any shorts. I did turn down the commutator and polish it. The field coils seem fine with an ohmmeter, but could one of them have a short causing this?
Is my generator shot?

Could the bearings be bad?

They're brand new sealed bearings, they turn easily and don't make any sound.
the heat in coming from the body of the starter and the rear bearing mount plate.

Could be a grounding problem....

Didn't you say you were getting a new wiring harness? Is your tractor freshly painted that paint could act as an insulator between parts such as motor to frame, generator bracket to engine block, etc, etc. I would address that with the new wiring harness you are planning to install!

I hesitate to post this as it would be obvious, but is the armature showing signs
of rubbing on the pole shoes?
Another thought:
If you removed the regulator wire from the field terminal, then the Generator would not produce a charge as there is no excitation, unless the field STUD is no longer insulated and is grounded to the case where it comes through it,-------
Just something to check.
Also check the condition of the commutator for any signs of the brushes arcing,
as each segment should look the same compared to each other.
Also check to see that the armature windings where they are soldered to the commutator, have not been overheated and thrown/melted the solder out of the connections, that would indicate a bad armature.

Also check that your brush wires are not touching anything they shouldn't
like the through-bolts or touching the case.
Heat is either rotational friction or excessive electrical production/ground.
You mention installation of ammeter, did you wire it correctly?
They are not an voltmeter where one side is grounded!!
they are a "pass threw" as in cutting a wire and hooking each end to the ammeter terminals.:bigthink:
Edit:
I just looked at your profile, sorry,
I didn't know you were versed in electronics.

Wiring harness is in the mail... Not freshly painted probably a 15 yo paint job from a previous owner.
I broke down and bought another tested working unit and a parts one (has a broken ear bracket) from my parts guy (Bullpen Antiques in Canajoharie, NY) I will do minimal cleaning to that and put it on to hopefully get it running.
The grounding doesn't make sense as a problem because its getting hot as heck just sitting there spinning and unconnected from everything. In order to see if the issue was a bad regulator or wiring I disconnected all the wires from the generator except the heavy starting cable from the starting switch. So after the engine is started there is no current path to or from the armature or field terminals, unless there is an internal ground path that is intermittent?
The only other issue I can think is if I resurfaced the commutator down too far past the point where the brushes would bridge more than 2 sections and that is causing internal currents that is inducing heating?

Armature spins freely with no contact on the shoes
Yep ammeter connected properly, initially things were working and by grounding the field terminal could force it into charge mode and the engine reacted to load and the ammeter showed charging current.

See my above post, this all happened after I reconditioned the generator (new sealed bearings) and turned down the commutator. the new brushes I used sandpaper to make sure they matched well to the commutator and cleaned them off. I checked the Armature side brush to make sure it was well insulated, the ground side brush had a good ground. There wasn't much room for the brush connecting wires but with the insulating sleeving it looked like they where fine and weren't showing as grounded.

Is the FIELD terminal grounded?

With the unit running what is the voltage at the ARMATURE stud of the generator?

I'm also curious about all the wiring at the generator,
you said "To eliminate any other issues I disconnected the wires coming off the field winding and the small wire off the armature"
Did you goof, and mix up the FIELD and ARMATURE wiring?

What condition is the voltage regulator in, did you happen to open it up and see?

***********************************

Scratch all that, with the unit running and only the heavy ARMATURE wire connected it still gets hot.
Sounds like the FIELD is grounded internally.

Another silly question, is you starter /generator a type "A", or type "B"?

I will pull the generator off the tractor this afternoon and try to troubleshoot it.
when I reassembled it I checked all the connections with for shorts to ground and found none.
It was running at full speed with no electrical connections back to the regulator field or gen terminals and the case of the generator was quickly getting too hot to hold my hand on it.
I've looked over several of the delco manuals and don't know what type it is, I will right down the part number off the tag. This generator has worked on it for almost 2 years before i decided to rebuild it.

Replaced the wire harness that came in today, took off the generator and opened it up.
Commutator is really scored up from only an hour of use. When I cleaned and reconditioned it I polished it up with 600 grit and cleaned all the dust and grit out of it with a few shots of contact cleaner before I reassembled it. It was nice and shiney and smooth, now it looks really worn. Is that a sign of on of the coils being shorted?
The coils seem the correct resistance that I found in some over threads. Trying to measure any resistance to the case may be showing something that is bad? After cleaning the carbon and copper out my meter wasn't showing any path to ground, but now it briefly read 1 Mohm before going up to about 10 meg, so maybe there is an intermittent short when it warms up or jiggles, I started drilling the pole shoe screws out and will hopefully get those disassembled so it can unwrap the old insulation and see if there's any place that looks like it is shorting.
Armature still passes growler tests.

Notice the crazed paint starting to peel, that was from overheating. Was not like that before I replaced the bearings and resurfaced the commutator

Either you did a super excellent job cleaning this, or it doesn't look like it's been getting too hot. The way you were explaining things I was expecting to see the windings on the armature to be burnt/black, or at least some discolouration.

From what I read on the tag PN1101996, it is the proper generator for the Cub.

Do you have a nice photo of the brush end of the generator case?
Somebody might see something that you don't.

I used this as my weekly or semi-weekly mower for over a year so I got familiar with how warm things are supposed to run on it. The generator got warm in normal operation, but I could hold my hand on it forever if I needed too and the bearing end didn't get hot at all. After the rebuild, can't hold my hard on it for more than 2 seconds and the commutator end bearing was getting noticably more hot that the other part of the end plate. I shut things down when that started to happen because I was monitoring the generator since I had done all this work on it.
I had already taken apart most of the commutator end since I'm trying to pull out the pole pieces.
I had taken pics before I touched anything but this website doesn't like my phone for some reason now and only will let me take a picture to post, not upload from my saved pics.

Sorry, I'm not seeing anything obvious at the moment

When you rebuilt the generator did you happen to read through this first?

https://www.onlycubcadets.net/pdf/S_G.pdf

I'm thinking your armature is still good, I don't see any discolouration of the windings, doesn't look like your missing any solder from the commutator risers, and the growler hasn't revealed any shorts.

You don't think the armature has been turned down to far though?
It looks like it was already turned down at least twice since you can see the solder joints and armature wires soldered into the copper?

If you put the Case in a drill press vice, and put a large screwdriver bit in the chuck , most times you can hold the screwdriver bit in the screw and it cant back out while you loosen/turn the screws removing them.:beerchug:

I had already drilled pilot holes and I opened them up enough to fit an e z out into them and was able to back them out. I have a pack of new screws in the mail since I knew they would get torn up. Definitely putting a bit of antisieze on them if I have to disassemble it again.
I pulled the coils out and the heavy A terminal coil looked fined after stripping off the old wrapping, the paper insulator was good and didn't look like any place for the coils to touch together, so I wrapped it in fiberglass tape.
The field coil I can't be sure if there was any wire touching the case. There where two spots under the coil that looks suspicious like a possible place it arced. I pulled of and carefully separated the gummy plastic dip and gave it the same fiberglass wrap, and then carefully filed down any sharp edge or spot on the poles.

Here's hopping those two suspicious spots were the problem.

There's only two ways for the generator to get hot, either friction like the armature rubbing on a pole shoe or bad bearings, or electrical overload like a grounded field winding.

I forgot to ask earlier, while the generator was still on the tractor did you happen to put a volt meter on the armature side and see if/what it was outputting?

Got back from a vacation and was able to look at the "good" generator and parts generator I got in the mail from my parts guy.
The good one was a yellow painted (off a cub) 1101996 that looks pretty much identical to the one that came off my machine, I'm going to clean the gunk out a little bit more and put new new bearings on it and see if that will work. It did spin fine when I hooked it to a battery.
The parts one i found the number is 1101970 after I cleaned it all off. That is a cw rotating one so its not a cub generator. But are the stator coils the same as the ccw versions so I can pull all the parts out and recondition them? the armature also has half the number of contacts on the commutator so is it wound different that I cant use it in a ccw starter generator? I need to know if i have to send this back if its not useful for parts.

I didn't think to check the voltage off the generator when i had it running unconnected.
I have a large variable resistor that I can hook up like the testing documents show as a "dumb" load and put an ammeter on that and a voltmeter to see if its behaving right if i ground the field coil.

I the armatures out of both starters i got and carefully filed and sanded the commutators smooth on the lathe. I put the one from the parts unit which looked to have the least wear in the generator body that was original to my tractor (with checked and rewrapped coils). I put 2 analog voltmeters on the tractor, 1 hooked to the generator armature terminal, and one hooked directly accross the battery. It started fine, initially it looked like the generator was outputting ok, but when i tried to manually short the F terminal to ground to make it charge nothing happened on the ammeter. I thought maybe the regulator is bad (which i checked and readjusted on the bench). I bought a new old stock on on ebay so I swapped that regulator in, still no making it charge. Also observed the voltage on it changed a lot when throttling up and down.
So i took the tested good generator i had ordered (cleaned commutator, new brushes and bearings, only cleaned the inside manually with a brush and wiping off look carbon and gunk with shop towels) reassembled it and put it on the tractor with the meters the same and the new old stock regulator. Started the engine great. Voltage on the A terminal steady and doesnt change throttling up and down. Grounding F got a strong charging current back to the battery and after running it for 20 min the battery charged up to the proper voltage.
I guess the field coils are internally shorted and causing issues? I cant see it being the Armature terminal coil because that is a heavy enough winding I could see the insulation between all the turns and it runs with enough torque when starting?
The coils from the 1101970 gen look like they are wound in the same direction as the other generator coils, are they both incidental replacements for the generator that was originally on the cub?

Here ya go, its been 65 years or so since I undercut the mica on an armature after I turned it.
this is how its done.
I still have a brass jaw armature chuck with my lathe tooling.
https://www.youtube.com/watch?v=YRy9gS47HMo

Thanks for the link but mica in the commutator is not an issue on any of them. I used a hacksaw blade on the first generator armature to clean it out and there is plenty of space on the other 2 I got.
The problem lies somewhere in the stationary coils on the poles.

With your "New" generator and regulator on the tractor, you said "Voltage on the A terminal steady and doesnt change throttling up and down"
What was the voltage? Sometimes it takes about 15 minutes for the generator to reach 13 volts, even with the engine at WOT.

It defiantly sounds lie it was the field windings on the old generator.

The needle on the voltmeter at the generator terminal wanders up and down a bit, i cant remember exactly but I think from 12-14V. The voltmeter on the battery started a little above 12 and got to just below 13 after running for about 20 min. The generator voltage stayed pretty contant even when i went to low throttle. With the old generator the voltage went way down to about 6 volts when I went to low throttle.

Is anyone very knowledgeable about delco generator parts here?
I've fully disassembled the original generator on my tractor and the for parts one that ended up being a cw spinning unit. The coils from the CW unit I can tell from powering with a bench power supply and using a compass needle that the cranking coil and the field coil are wound in reverse of the ccw coils from the generator originally on my 70. I can actually probably change how the wires connect to the field winding so it will have the same polarity as the ccw unit to use them since i was going to rewrap the coils anyway.
The question I need answered is are the armatures the same for both rotation generators? The cw rotating unit looks like the armature is a relatively modern replacement that has half the number of commutator contacts and had virtually no wear on it. The previous one probably was replaced because the pole shoes show wear on the pulley end from a worn out bearing on the pulley side.
I'm stripping the paint off all the parts and painting everything with ceramic black engine paint

Ok so I finished rebuilding one complete unit from parts.
I have to take the poles and coils out of the unrestored working one to finish rebuilding the body of the generator that was originally on the tractor. My only question is if the armature with the fewer commutator sectors will work the same as the other one. Looking up replacement armatures on ebay the sellers list both CW and CCW units that they replace, so It should work fine?? From rewinding the coils i figured out the difference is the polarity of the windings (cant reuse the series winding, was able to switch polarity of the leads on the field coil and use it in the rebuilt unit)
Put voltmeters on both battery and armature terminal. Analog voltmeters were showing about 14V on both. could see the voltage wobble a bit as the governor dwelled a bit up and down. when i throttled down the voltage stayed the same and was more stable as the rpm was more steady at low speed. After about 20 min when I throttled down and idled a little while before cutting it off the voltage of the battery was stable. I even double checked the accuracy with my digital meter, the more recently calibrated meter showed it was 13V.
The body of the generator got warm much more slowly as the heat from the bearings spread from the end plate to the body. It does get warm but it seems the bearings are more of a normal amount of heating.

I cant help more then everyone already has but if you buy those ones of ebay for like $120 or probably more now. Make sure every thread hole or anything you are not using gets sealed. I used black rtv because the case is black. But I have ruined 1 of them with water getting inside and another I was able to save with cleaning. The one I saved I think water came in from the end caps? This is from sitting a year or something outside unused. My 2 cents... Good luck getting yours figured out though!

I was looking at the eBay listing because I can't find any Delco parts list that show what the parts would be for the 1101970 CW generator. If the people selling the new armatures list the armature that looks like the one that came out of it as being a replacement for starters that rotate both CW and CCW (seller lists the new armature as a replacement for 1101966 as well as 1101970) then it should be useable to complete rebuilding another unit. (So I have 2 working units)
When I finish with both of them I will put a little rtv in the notch in the end so water want get in. The 70 lives in a shed so it won't have any problem with being weathered.
I stripped all of the case parts and used a high heat ceramic low gloss paint. A thin layer of paint so It conducts heat away better and flat black to increase radiation, any little improvement to help it shed the heat.