Help with Johnny generator, please...

[royal0014]

Johnson Super Seahorse Electramatic RK-28 40hp (1966)

Attempting to determine if the gen. is any good. I am clueless.

Have continuance between field and armature posts. Have cont. between each post and the frame (short?) Took apart and removed armature. No cont. between armature and commutator. Continuance between arm. and shaft, but not comm. and shaft.

With armature out, still have cont. between posts and each post to frame. Brushes look good, little wear. Is it ok for bare brush wire to contact inside of frame?

Thanks to all........

 

[Chris1956]

Re: Help with Johnny generator, please...

It has been a long time since I messed with one of those. You need to disassemble generator to test it.

Commutator to commutator (opposite side contacts only I think) should be only continuity the armature has. Commutator to armature continuity is bad. Check continuity across field. Only continuity should be on field winding. No continuity to generator case.

 

[boobie]

Re: Help with Johnny generator, please...

Also been a long time for me for this generator work. If I had it in front of me I could tell you right away. The only thing I could suggest is putting the gen back on the mtr, GROUNDING out the FIELD terminal and rev up the mtr. If the ammeter shows high voltage the gen is okay. If not, gen is bad. But if you get high voltage you have a bad regulator. Hope this helps. Also check that you have battery voltage on the BAT terminal of the regulator.

 

[F_R]

Re: Help with Johnny generator, please...

How to bench test a generator:
1. Ground the frame to battery neg.
2. Ground the field terminal to frame.
3. Connect the armature terminal to battery pos. Armature should rotate like a motor. If it does, generator is working ok.

The above test also polarizes the generator, so no need to do that again.

 

[boobie]

Re: Help with Johnny generator, please...

FR. The generator can "motor" okay on a bench test but what happens when the generator is turning at it's proper rpm or higher? How about the windings in the armature seperating from the commutator due to centrifical force due to bad connections ?

 

[royal0014]

Re: Help with Johnny generator, please...

Thanks for the answers, but me still confused.....

I did the 'motor' test before I took it all apart, spun good, no sqeal bearings.

But I took it apart because meter was showing continuance between the two posts, and between each post individualy and the frame.

Once apart, windings, bars, and spacers all looked in excellant shape, and all tested good. No short between commutator and armature. Brushes looked to be near 100%, very little wear.

BUT, with the armature out, I was still showing continuance between the posts and the frame I assume short??

Well, I can't really do anything else with it, so I put it all back together and put it back on the engine. Hitting the water today, so we'll see what happens...

I can find generators to replace, just can't afford them right now. But I have not found the voltage reg. anywhere.

One last question (or two).... If the gen is shorted, will it fry the voltage regulator? And if they are both bad, will it damage the battery? Just bought a brand new marine starting battery yesterday.

Taking the 9 y/o out for his first trip on Daddy's boat today. I must have answered a thousand questions while I worked on it yesterday Hopefully I won't be tempted to use him for cut-bait.......post back later w/update. Thanks to all.

 

[F_R]

Re: Help with Johnny generator, please...

Don't be dreaming up trouble. If it motors, it is ok. See the circuit and you will understand why you get continuity.

No, there is no way a bad generator can fry a regulator.

No it can't damage a battery. Discharge it if shorted, maybe.

I don't get the question about centrifugal force. It can't rotate faster than it was designed to do, which is 5000 (engine) RPM. It won't motor anywhere near that fast. Bad connections? Exactly what kind of bad connectons are we talking about? If bad battery connections, it simply won't work. You can even run it without a battery.

Before anybody asks, you can't use a car regulator. Some of them will seem to work, BUT THAT CAN fry the armature, due to too high a current regulator setting.

 

[royal0014]

Re: Help with Johnny generator, please...

Thanks for the post FR. I know a car v.r. won't work.

UPDATE: Took it out with the kid today. Had trouble with the L/U slipping out and high revving. Electramatic, I'll start another post for that trouble.....

When I could get throttle up, the ammeter showed output. About 15 or so amps at 3/4 throttle, and nearly 20 at WOT. Needle moved more or less with the RPM's. I forgot to take my multimeter with me to check actual output. Maybe next time; I was more interested in the wildlife today

At least one thing went right today, 'cause the fish weren't cooperating. The nine y/o got a nibble and missed, that was it for the day!

Thanks for the answers. Look for another post from me about the Electramatic L/U

 

[fwbdave]

Re: Help with Johnny generator, please...

For what its worth....I was in the parts business for 30 years. Back during generator and early alternators heyday, Standard Ignition sent us a letter refering to Voltage regulator returns. They said 1/2 of one percent of all V/Rs returned as defective were actually defective. All the rest were other problems.....David

 

[Willyclay]

Re: Help with Johnny generator, please...

Taking the 9 y/o out for his first trip on Daddy's boat today. I must have answered a thousand questions while I worked on it yesterday Hopefully I won't be tempted to use him for cut-bait.....post back later w/update. Thanks to all.

Keep on answering his questions Dad and in a couple more years he might be able to handle the maintenance on that great old motor for you. Be safe!

 

[F_R]

Re: Help with Johnny generator, please...

15 to 20 amps is too much. Do you not have a voltage regulator on it? I'm wondering how you got it to charge at all without it. Grounded field?? Anyway, that high current is what fries armatures. The regulator is set to 10 amps.

 

[royal0014]

Re: Help with Johnny generator, please...

FR : Yes, it has a voltage regulator on it. I neglected to mention, the reason I took it off to check it out in the first place was because I tested both posts shorted to ground. Can't remember if the volt reg was wired up at the time....I'll go back and check again.

 

[royal0014]

Re: Help with Johnny generator, please...

Ok, so retested. Disconnected the wires from the field and armature terminals on the volt reg. Both were reading continuance to ground, but the battery terminal was not.

Maybe the guage was reading high, even though the needle was moving with the engine RPM"s. It is 40+ years old. Next time out I will take along my meter to get a actual output reading.

Afraid it will be awhile before I can go out again, work schedule has me messed up the next couple of weeks

Thanks again

 

[F_R]

Re: Help with Johnny generator, please...

Well sure, the regulator's field terminal would have direct continuity to ground. That's what makes the generator put out. When the voltage goes above about 14.5 volts, the contacts open and it is then grounded through resistors. That's what limits the gen output. Not sure about the Arm terminal. Never thought about it much. And of course the bat terminal isn't grounded because that would discharge the battery.

 

[boobie]

Re: Help with Johnny generator, please...

FR. The centrifugal force thing is like this. Back in the 60's I worked in an auto electric shop. Had a gen on a '55 OLDS that would charge fine at idle and just a little above. When mtr was reved up it would quit charging. Come to find out the the soldered connections on the armature between the armature windings and the commuator were bad . As the armature spun faster they would open up and gen would quit charging. Back to idle or just above it was fine. By the way, I liked your diagram as that should answer any questions about continuity.