Dynamo Trouble

[Freebirdbeachbum]

All the sudden (between starts), the charging warning lamp lit up. I removed the side cases and inspected the wiring and belt and nothing looked problematic. I removed the belt from dynamo and put a charge to it and the dynamo runs. I also put a meter to the battery while the engine was stopped and when running with no difference in voltage (6.35 or so). Did the regulator crap out suddenly?

Anyone know of good trouble shooting guide for a typical 6 volt system like this?

 

[john zibell]

All the sudden (between starts), the charging warning lamp lit up. I removed the side cases and inspected the wiring and belt and nothing looked problematic. I removed the belt from dynamo and put a charge to it and the dynamo runs. I also put a meter to the battery while the engine was stopped and when running with no difference in voltage (6.35 or so). Did the regulator crap out suddenly?

Anyone know of good trouble shooting guide for a typical 6 volt system like this?

Schematics are available to folks in the downloads area if you upgrade your account. Stating which bike you have will also help. To upgrade see this. https://www.guzzitech.com/forums/threads/user-account-upgrade-donations.14025/

 

[Freebirdbeachbum]

Schematics are available to folks in the downloads area if you upgrade your account. Stating which bike you have will also help. To upgrade see this. https://www.guzzitech.com/forums/threads/user-account-upgrade-donations.14025/

Thanks John.

The bike is the '65 Lodola in my signature.

I have the owners manual, parts manual and service manual, including the schematics for the electrical system.

Over the weekend, I removed and cleaned the dynamo and lubricated the bearings. The brushes looked good and wiring seemed all in-tact. I also checked the continuity of the wires in the system without finding any issues.

I'm looking to replace the regulator as the next step, unless someone has another idea.

 

[Freebirdbeachbum]

Thanks John.

The bike is the '65 Lodola in my signature.

I have the owners manual, parts manual and service manual, including the schematics for the electrical system.

Over the weekend, I removed and cleaned the dynamo and lubricated the bearings. The brushes looked good and wiring seemed all in-tact. I also checked the continuity of the wires in the system without finding any issues.

I'm looking to replace the regulator as the next step, unless someone has another idea.

Update (although it appears I'm just updating myself):

The charging system started working again as mysteriously as it stopped. I had already purchased a replacement regulator so I'll keep it on the shelf until the system decides to quit again.

 

[scottmastrocinque]

Not intimately familiar with the Lodola but very familiar with Dynamos (Dynastart) as used on BMW Isettas.

Forgive me if any of this isn’t applicable.

I assume you have brushes on your dynamo. Also spring steel roller springs to keep tension on the brushes. The brushes should be isolated from the housing. Sometimes they ground out causing a failure.

In my pictures below, I had to make a new mounting plate from circuit board material, (the one at 2-3 o’clock) and pop rivet it onto the stator. That stopped my power on/off like you are experiencing.

Also, the starting posts can short out to the housing causing the same issue.

Check the commutator surface also. They can become heavily oxidized. Clean with a gentle 0-0-0-0 steel wool wiping. It used to be alternator shops would shave down the surface a thousandth or two to get to clean fresh metal. I haven’t seen any shops like that though for years and years.

This is always the first place I check when Dynamo current goes on and off.

I also physically touch and feel the magnets on the stator housing to make sure they are intact. It can be maddening sometimes trying to track down a loose connection or broken soldering point.

In all the Isetta work I have done, I’ve never actually found a rotor in a dynamo that experienced a broken winding. Those buggers are pretty well made back then.

The next would be carefully examining wiring for any evidence of severe bending or pinching marks.

Also, look at any and all connectors on a motorcycle of this age. It is not uncommon to have wiring connector pins that have worked their way out of the connector. I gently push pull each wire to check for solid retention within the connectors.

Good luck! I adore your motorcycle very much. She’s way cool.

I presume your dynamo is similar to this one from a 300cc BMW Isetta.

 

[scottmastrocinque]

Found some photos of what I think you have.




I also would check this. There is a section of the loom that passes down between the oil tank and the battery box to feed the points, dynamo and brake light switch on the r/h side of the motor, so this passes underneath the swinging arm and therefore has a point of stress there. This image shows the failing point on that wire.

Please check yours.

 

[Freebirdbeachbum]

Found some photos of what I think you have.

View attachment 27199View attachment 27200View attachment 27201


I also would check this. There is a section of the loom that passes down between the oil tank and the battery box to feed the points, dynamo and brake light switch on the r/h side of the motor, so this passes underneath the swinging arm and therefore has a point of stress there. This image shows the failing point on that wire.

Please check yours.

View attachment 27198

Thanks Scott. I'll be going thru the wiring again if and when the problem returns. I did check the continuity of each wire that serves the system when it wasn't working and they all checked out. My dynamo does look similar to the one here except it didnt look like it was once on fire like the one pictured here. I wish i had taken some pics when i had it apart. I also cracked open the regulator and cleaned the contacts. It's a Bosch and the official parts manual lists a Marelli so it was probably replaced at some point. Neither the dynamo or regulator showed any signs of moisture or corrosion or fire/heat.

 

[scottmastrocinque]

Isn’t it nice to know that your update was not just for you!

I enjoy updates as well as questions.

It keeps my mind chugging along and helps to stave off early Alzheimer’s.

 

[Freebirdbeachbum]

Update (although it appears I'm just updating myself):

The charging system started working again as mysteriously as it stopped. I had already purchased a replacement regulator so I'll keep it on the shelf until the system decides to quit again.

Another update:

The charging system stopped working again suddenly. I R&R'd the regulator but that didnt do it. I'm going to remove the dynamo again and see what I can see.

 

[scottmastrocinque]

Apologies as I don’t have firsthand knowledge of your setup but I believe that you have carbon brushes on your dynamo like these in the photos.

These brushes are there and held by coil springs.

I usually find the brushes worn too short to make constant contact, or the coil springs are broken.

Check those first. Given the age of the bike I’d bet those brushes are shot.

 

[Moto-Uno]

This may sound a bit irrelevant , but when I used to service H-D Sportsters , I found the insulating
sleeves the brushes ran in would swell on occasion and cause the brushes to bind in them . Peter

 

[Freebirdbeachbum]

Apologies as I don’t have firsthand knowledge of your setup but I believe that you have carbon brushes on your dynamo like these in the photos.

These brushes are there and held by coil springs.

I usually find the brushes worn too short to make constant contact, or the coil springs are broken.

Check those first. Given the age of the bike I’d bet those brushes are shot.

View attachment 28173

Everything looks good. The coils are strong and the brushes are making contact.

 

[Freebirdbeachbum]

I just realized I never closed the loop on this thread. I had a specialist look at the dynamo who ran some tests and deduced the armature windings were bad. He referred me to another specialist who did the re-winding and now it's working fine. Thanks all for the input.

 

[Raven]

Thanks for posting the final outcome. So many times things are left unresolved.

 

[Moto-Uno]

, Peter