Armature demagnitized?? $90.00

Dave1929

Dave1929

Junior Member
My generator on my '29 Tudor stopped working the other day. I took it to my local generator shop. A few hrs later I got a call saying that it was ready. The gentleman there said it would be $90 to get my generator. I'm ok with that as long as it works right? My next question was "what was wrong with it"? All he said was that my armature was demagnitized. What does this mean? How did that happen overnight and how do I stop it from doing it again? How do you remagnitize an armature?
 
There are all kinds of things wrong with this explanation, but then I don't know a lot about auto electricity. However, As I understand it, it's the field coils, not the armature that get magnetized/excited,(Please someone, correct me if I'm wrong about this) And the way they get "Excited" is by turning on the key. To demagnetize one thoroughly, the generator must sit on the shelf for years, in fact, Automotive generators get the coils excited by turning on the ignition, not by residual magnetism. And it ain't worth $90 to fix one! Someone else will probably give you a better explanation of what was wrong than I can. I think you can slop the hogs with that story!
Terry
 
I misunderstood the guy when he called. He told me when I went to pick it up that the armature was magnetized. He said when he put it on the growler and held a hacksaw blade to it the blade started jumping. I'm not sure what this means. He put a used armature in my generator and a new bearing. That's what cost me $90.
 
Any ideas how an armature gets magnetized and goes from charging one day to not charging the next? The new used armature worked as I am back on the road.
 
If he placed your armature on a growler and with the hacksaw he had it vibrating erratically, there were shorts in the armature. Bad bearings in a generator could cause such an occurrence if the armature starts rubbing the field coils and wears thru the insulation of the armature.
 
Re: Armature demagnitized?? $90.00-why laquer thinner is bad for shellac on wiring

Does anyone know if the shellac on the wires of an armature can be dissolved if sprayed with laquer thinner or brake cleaner or any other common cleaners?

What cleaners should one avoid using?
 
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You want to use products specifically for cleaning motor windings.

Description
Keeping electrical parts clean takes special care. Your facility can keep machinery up and running with this cleaner, which features a non-staining, non-corrosive, non-flammable design to withstand tough workplace conditions.
Helps keep electrical parts clean without leaving a residue.
Non-flammable formula is designed to resist staining, corrosion and conductivity. Features a high dielectric strength of 37,500V.
Contains no 1,1,1-Trichloroethane.

https://www.officedepot.com/a/produ...17&gclid=CJHGoviKudwCFdSYxQIdMEoGjg&gclsrc=ds
 
160B said:
You want to use products specifically for cleaning motor windings.

Description
Keeping electrical parts clean takes special care. Your facility can keep machinery up and running with this cleaner, which features a non-staining, non-corrosive, non-flammable design to withstand tough workplace conditions.
Helps keep electrical parts clean without leaving a residue.
Non-flammable formula is designed to resist staining, corrosion and conductivity. Features a high dielectric strength of 37,500V.
Contains no 1,1,1-Trichloroethane.

https://www.officedepot.com/a/produ...17&gclid=CJHGoviKudwCFdSYxQIdMEoGjg&gclsrc=ds
Click to expand...

Thanks for the 'memory jog"


The IBM "Gold Can Cleaner" that we used in Vietnam in 1967 and 1968 ... contained Carbon Tetrachloride WHICH causes kidney damage as I remember.

Sometime in 1968 I remember getting a RECALL on all cans of cleaner.

They replaced with new cans labeled 1,1,1-Trichloroethane see above

Sometime later they found that the 1,1,1-Trichloroethane was HAZARDOUS also.

We had to remember the name because for years after that I would run across cans with 1,1,1-Trichloroethane in old stock rooms and customer's sites.

I do not remember what they replaced the 1,1,1-Trichloroethane with.

I see from your post that Office Depot says it was Tetrachloroethylene.

I sure am glad that I did not have to fix too many IBM 407 PRINT UNITS with their "Selector dog" springs or IBM 1052s ... many cans of "Gold Can cleaner" were used on each 407 and 1052 repair.
 
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Years ago when I was in the computer business, we used a product called CRC.
I have no idea of the compounds in it, or if it had a specific number associated with it.
It was non hazardous
 
Kahuna said:
Years ago when I was in the computer business, we used a product called CRC.
I have no idea of the compounds in it, or if it had a specific number associated with it.
It was non hazardous
Click to expand...

CRC
Electronic Contact Cleaner;Aerosol Can;20 oz.;Flammable;Non Chlorinated Automotive Cleaner Item
Electronic Contact Cleaner

Cleaner Container Type Aerosol Can Cleaner Container Size 20 oz.

Net Weight 19.00 oz.
Cleaner Solvent Base Solvent
Flammable/Non Flammable
Chlorinated/Non Chlorinated Non Chlorinated
pH N/A
Cleaner VOC Range Contains No VOC
Ready to Use/Concentrated Ready to Use
Cleaner Application Fleet/Vehicle,Parts Washing
Color Light Yellow
Boiling Point 310 Degrees F
Freezing Point 172 Degrees F
Flash Point 172 Degrees F
Pour Point 0.89 Degrees F
Specific Gravity 0.89
Features Plastic Safe
Standards RoHS Compliant


https://www.grainger.com/product/1Y...17807&ef_id=WWoVQwAAAGNKXQPA:20180725024725:s
 
I use dry compressed air to blow clean the armature and fields. If it is oily and dirty, then I also used gas, a soft paint brush, and blow dry it as quickly as possible.


I wouldn't use lacquer thinner.
 
There is no power going to the armature on a Model A generator, it is self contained single wire out unit. How ever there is a bit of residual magnetism in the shoes that support the field winding, just enough to start the generating process.
 
Tom Wesenberg said:
I use dry compressed air to blow clean the armature and fields. If it is oily and dirty, then I also used gas, a soft paint brush, and blow dry it as quickly as possible.


I wouldn't use lacquer thinner.
Click to expand...

Tom,

I thought that L Thinner was bad for Shellac ...

Thanks for lacquer cleaner comment ...I know that brake cleaner was mostly Lacquer thinner until recently before the EPA changed everything with VOC s (Volatile Organic Compounds.)

I do not know if the replacement will dissolve wire coatings or not, which is my reason for bringing up the topic in first place .
 
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Dave1929 said:
I misunderstood the guy when he called. He told me when I went to pick it up that the armature was magnetized. He said when he put it on the growler and held a hacksaw blade to it the blade started jumping. I'm not sure what this means. He put a used armature in my generator and a new bearing. That's what cost me $90.
Click to expand...

A short in the armature winding will cause the blade to vibrate.
 
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