Calling all electricians

[loppylugs 8,429]

I have a Coleman Powermate Ultra 2500w. Gas powered generator. A while ago I plugged in an electric kettle and she quit generating. No breakers tripped etc. pulled the stator and rotor. Stator continuity checks out OK. Rotor continuity also seems fine. No sign of burning or any other damage. There are no brushes on the rotor. It has a couple of diodes, and capacitors mounted on the topside. I replaced those and a larger capacitor in the housing but no luck. I cannot find a circuit diagram, but if anybody has any ideas all would be welcome.

Dave

BTW. Tried flashing the unit with a battery, but no results.

[Ayupmeducks 1,730]

Has it any circuit breakers?? If so are they faulty?

Never had to flash any alternator that I've overhauled, and overhauled a fair few Dave.

Basically the rotor is the rotating magnets, have you checked to see if there is any voltage from the stator winding?? You might have a couple of coils gone open circuit.

Is there an exciter winding controlled via a PC board anywhere??

There really isn't a lot that can go wrong with them, I'd suggest you get an multi meter set at 200 volts AC, and check to see if you have any output at the outlets, if you have say, 20 to 50 volts, my guess would be open circuit in one of more of the stator coils, or stator coil wires burnt off.

You may need to do a continuity test of the stator windings, if you can get at the coil connections, try getting a continuity reading of each coil. Mostly though, they are fastened to the end windings and varnished with the winding..

You mention diodes, there are a couple of diodes buried in the end of the rotor on brushless generators, have you checked those??? The caps are for voltage regulation.

[MELTONSTILTON 452]

Do as above, or do as my Dad did with the telly when it did not work, give it one almighty thump........it worked almost every time

[Ayupmeducks 1,730]

I used to have a mate in California, if something didn't work, he'd take it outside, get his rifle and shoot the mongrel...Can't recall now how many computers he put out of their misery..

[Trevor S 2,003]

I often feel like doing that to the TV, what with all the crap that is on the tube these days.................

[loppylugs 8,429]

Thanks for the responses. I may just have to take it out and shoot it or at least get a dollar or two for the copper in the thing.

There are breakers in the unit and they check out o-k.

You seem closest in your thoughts, John. I started it on Saturday and plugged in a 60 watt bulb. That flickered for a while and I thought maybe things would come back up but it faded out. The bulb is o-k. Your guess at OC windings in the stator makes sense. That was the way I was leaning.

I did check the diodes on the rotor they seemed o-k but I replaced them anyway. Didn't make any difference. No pcb boards in this unit'

Probably cost more to fix than the whole thing is worth. Did someone say "Made in China?"

I'd kick the so and so but I'd probably just hurt my foot!!!!

Not sure if I could drop the jenny off and use the motor for something. It is basically a lawn mower motor. Maybe I should build a go-cart.

[Ayupmeducks 1,730]

The rotor driven end and engine share the same bearing Dave, the shaft is a taper fit, female on the rotor, male on the engine.

There's no way you can use the engine for anything, other than another generator rotor/stator.

If you can get to the diodes, check the windings resistance both sides and compare them, they must be almsot the same.

On some, there is an excitor winding in the stator windings, but on a small one like that, probably not needed.

I have a 6Kw version of yours, though a lot older and it has a "slipring" assemby on the end of the shaft, it's at right angles to the shaft, odd type.

You might find a complete stator/rotor assembly on Ebay, when I was looking for a manual yesterday I noticed several such sales at reasonable prices, albeit 6Kw units, but there could be more or different output sizes.

[loppylugs 8,429]

Yes, mine is the taper type of fit, John. I've already put more hours into this thing than it is worth. I have another jenny that is working ok. Probably just scrap the Coleman and have done with it before I hurt myself in some way fooling around with it. Reluctant to go the e-bay route. Might just buy another load of problems! Thanks for your thoughts.

[Ayupmeducks 1,730]

Just a thought Dave, sounds stupid, but is the rotor slipping??? I hope you didn't oil the tapered shaft??

Whenever I reassemble a generator to the engine, I slip the rotor onto the taper of the engine, thread the long bolt in to pull the two together, then I remove the bolt, place a heavy piece of wood against the shaft, and give it a good whack with a heavy hammer, then replace the long bolt and tighten up.

[loppylugs 8,429]

No, I don't think it is slipping. Real hard to get the so and so off. Think I'll cut my losses on it.

[Ayupmeducks 1,730]

Yeah, they are very hard to part, shock and gravity, I know no other way.

It's similar to chainsaw flywheels and small engine flywheels, all bloody taper shafts.