Sullivan Dynatron

[Wasted wages]

I have a Dynatron starter on 24 volts that has developed a bad vibration and growl... I tore it apart and cleaned it up and put new brushes in it and greased the bearings..
The armature looks good, nothing loose or out of balance... the vibration is there with or without the pulley on it.

The only thing that looked suspicious were the two brass bearing bushings. They seemed loose in the end caps.
Has anyone tried installing ball bearings in place of the bushings ?
Other than that, anyone know if parts are available
directly from Sullivan ? I'd rather try to repair it or modify it than toss it out.

 

[Brian Sorgente]

I've had good luck buying them direct in the past, but it was years ago. Definitely worth giving them a call to see.

Brian

 

[Mark Bullard]

Sounds like the armature has open winding. Everytime the brushes past the open bar on the com will make it feel like it is out of balance or growl.

 

[Wasted wages]

Good point Mark...
I took it apart again yesterday, the bushings have a little wear but not really enough to
Cause the symptoms...

Stuck it all back together and the vibration is still there.. I did notice a lot of ozone smell when I cranked it back up....

Probably time for a new one...

 

[Rodney Rogers]

Did you check for a crack in the magnets ? You can pull the armature chuck it up in a drill press spin it up to make sure it has not got out of balance .

 

[Rodney Rogers]

You can clean the Commutator with a Pencil eraser if it needs it .

 

[Rodney Rogers]

I had a starter one of the magnets came unglued .

 

[Wasted wages]

Magnets are all in good shape, I'm leaning towards an open winding as Mark pointed out...
There was a lot of arc flashover on the commutator, the brushes were trashed, so replaced them and polished the commutator.
I checked the balance of the armature on my prop balancer....it runs nice and true.

So, far nothing seems to have helped it..

 

[Mark Bullard]

If you can look at where the wires hook on the bars of the commutator you may see the problem. I have lifted the hook up and scrap the wire and push it back down. Then take a solder gun of at least 250 watt and solder the wires at each bar hook. This will fix most of the time if the wire is not broke further to the slots. but you can splice the wire if you see that. Then after you do this take some nylon string and wrap the wires close to the commutator with five or six turns stacking the string next to the turn before. Also use a thin piece of ply cut to fit the slots where the wire at. Then CA the string and ply in the slots and cure it out.
What happens is the wires come loose and lose there connection on the bars. It is speed and running at 24 vdc or 2 / 4S lipos in series that causes this. I have done this many time for myself and others to fix starters.
I am still running a starter that I got out of a trash can that had slung the wires out of the slots. So I rewound it.
Being that I am in the electric motor repair bussiness I have the materials on the shelve.

 

[Wasted wages]

Thanks Mark, I will pull it apart again and check the commutator bars at the winding connection.... I do have a good heavy duty Weller soldering gun...

Can I just ohm the winding/ comutator bars 180 degrees across from each other ?
Or is it wound differently?

 

[Mark Bullard]

You can put a ohm lead on one bar and start read to the next bar and keep going around the com. Don't know if the ohms will be that high to tell the differance but you may find the open bar. There again it may read all the way around and only opens at running speed. The way it is wound is you start with one bar with the wire to the starting slot around the slot span to the number of turns. Then depending on which way it is wound after the turns you come to the next bar and go to the next slot. This goes all the way around until you get back to the end to where you started.
Also a lot of times these are wound on a machine and the film is not removed to where it goes under the hook of the bar. This is where you lose the connection. And by lifting the hooks up and scraping the film off the wire at that point, you can push the hook back down and solder.

 

[Wasted wages]

I guess ohms was a bad choice of words...I really meant continuity..
I'll check it out.
My thought was that the bars were 180 degrees in opposing direction to power the winding as it passes the two brushes at the same time? Not so ?
Maybe my thought process is flawed in this respect..

Thanks again Mark!

 

[Wasted wages]

After re reading your last post, I think I'm beginning to understand...they are not necessarily separate windings, but a loop of wire with conection points at each bar...
Correct ?

 

[Steve White]

After re reading your last post, I think I'm beginning to understand...they are not necessarily separate windings, but a loop of wire with conection points at each bar...
Correct ?

Each pole in a motor is independent and an independent winding that's how the commutator able to time it.

It's about the electrical arrangement, not the physical property of how the terminations to the commutator are made.

The motor is probably wasted Frank. The only thing that could be repairable would be bushings, brushes, maybe a loose magnet and commutator could have a bad solder joint to a winding or be filthy dirty.

This type of DC motor is typically from 3 to 7 poles on the armature - more poles = more consistent low speed torque.

 

[Wasted wages]

Thanks Steve... it's perfectly clean, I've taken it apart 3 times now and brakecleaned the hell out of it.
Magnets are perfectly intact.
Installed new brushes..
Moly greased the bushings...
New pair of 12 volt batteries.
New speedmaster handle with a new 24volt
Relay mounted on the starter.
New 10 gauge wire from batteries to the relay.
Balance checked the armature twice.
Bushings are worn, but I've seen a lot worse.
Shaft has no wear spots on it.

There is no obvious reason why it growls and vibrates like it does. Pulley on or off makes no difference....

It has to be a dead commutator slot..
I'm going to break it down once again and solder all of the tabs as Mike suggested.

Failing that, its going in the trashcan.

 

[Steve White]

That's the most likely place it would fail electrically - at the commutator. Losing a winding internally due to breakage, is a rare thing - assuming it's not burned down - and it isn't, as you you see/smell heat evidence if it smoked it like that.

I gave a Dynatron away in the Christmas thread year before last - you should have blew it up sooner.

 

[Wasted wages]

That's the most likely place it would fail electrically - at the commutator. Losing a winding internally due to breakage, is a rare thing - assuming it's not burned down - and it isn't, as you you see/smell heat evidence if it smoked it like that.

I gave a Dynatron away in the Christmas thread year before last - you should have blew it up sooner.

The only thing that could make these starters any better would be replaceable ball bearings... it really look like there is enough "meat" in the end caps that they could be bored out and fit with a bearing.

Sullivan "stakes" the aluminum part of the two end caps where the bushing goes in making it impossible to service, replacing the entire cap/brush holder assembly looks to be the only option... unless I'm missing something.