Model A generator problem
 

Hoping someone has an answer ! My generator stopped charging, cleaned, put in New brushes, replaced field coils, cleaned armature, new diode cutout. Polarized it, when I first start engine it will show amperage on the car gauge , At idle ! a little more rpms and it will go to 15 to 20 amps. Then it seem like a thermal breaker or something just shuts it off and won't come back up until I do a complete shut down and restart ???????? I have also cleaned battery connections, disconnected light switch from steering column to try to avoid any possible shorts. But no difference. Thank you for any idea's!

Re: Model A generator problem
 

If this is an original generator, try a different cut out.

Re: Model A generator problem
 

Reduce the charging amps by moving the third brush. 20 amps is way too much.

See what happens when you have it set to charge about 10 amps.

Chris W.

Re: Model A generator problem
 

I agree with moving the brush and reducing the charge rate, I prefer it at 3-4 amps.

I also agree with trying a different cut-out. Is yours just a diode cut-out or an EVR ?
Try to find an original cut-out, they are pretty bullet-proof.

Re: Model A generator problem
 

Have tried new cutout.

Re: Model A generator problem
 

Thank you for the information , will try moving 3rd brush.

Re: Model A generator problem
 

A diode is like a one way check valve. A cut out was originally an electromechanical device to switch the generator on line after it reaches enough voltage to close the circuit. I know that folks still refer to the diode look alike as a cut out but it's not the same critter. Depending on what type of diode was used makes a big difference. Some are near indestructible and some are crap.

Was the armature tested with a growler for opens or shorts. Armatures and field coils can be affected by heat if there is a crack in a wire or a short. A battery can also be affected by heat.

Make sure your battery connections and ground paths are in good condition and tight. Adjust that 3rd brush to limit your amp output. Over amping will cause more heat and a three brush generator always has output unless a modern voltage regulator is installed so they always create some heat unless regulated. The battery is your voltage benchmark so it has to be in good condition and well connected.

Re: Model A generator problem
 

If moving 3rd Brush (around 10 amps or less) does not solve the problem and you have the old type relay cut out, I would reinstall it and see if that helps. Also, Although, not a model A, but on one of my vintage tractors with a generator, I had something similar, and after chasing my tail, found a loose connection on the ammeter. Drove me nuts for a while, and just kept at it by process of elimination. Hope ya get it figured out!

Re: Model A generator problem
 

Thank you

Re: Model A generator problem
 

Have tried about everything people have suggested with out any change. Have not had armature on a growler but it does put out voltage and amperage. Amperage seems to high and kicks it off ! One last thought ! I have not undercut the armature could that make a difference?

Re: Model A generator problem
 

Check battery connection to frame, and check ground path from frame through engine mounts to generator. Bad ground connection between battery and generator can cause weird problems.

Re: Model A generator problem
 

Some [most or all] aftermarket diode cut-outs or EVRs are ruined by polarizing.

If the generator motors when power is applied directly to it then 99% of the time its fine.

Re: Model A generator problem
 

A diode cutout won't be hurt by polarizing the generator. EVR - perhaps.

Problem could also be a bad battery. Check resting voltage and electrolyte levels.

Re: Model A generator problem
 

I want to thank everyone for their help. This one is a Real stumper ! I have tried everything anyone has suggested. Adjusting third brush does not seem to make any difference on the amp gauge, (new gauge ) generator will motor ! It has not been on a growler ! If I start the engine and leave at the very lowest idle it will charge at about 7 amps ! Give it any throttle at all and it kicks off ! When I bought the car years back, it has always showed about 20 amps on the gauge all the time it was running, (for years ) finally on a drive last fall , it stopped charging, a couple miles down the road it started charging again and got me home. But now I have this problem.

Re: Model A generator problem
 

You need to get the armature checked. It could have a flying short that allows it to work sometime and sometimes not. The segments need to be undercut on generators. While you are getting the armature checked, get the battery checked too and clean the terminals. New amp gauges are not that great so would not completely trust it. If you have a analog or digital meter to check with, you might try using it. Unless you have a sealed battery, have you checked the water level in it?

Re: Model A generator problem
 

Redmodelt, thanks for your time, I believe what your saying might just be the problem, sometimes charges sometimes not. Will have to find someone with a growler in my area. Thanks again.

Re: Model A generator problem
 

Does it motor when power is supplied or not ?