Small Generator Wont Make Power

Status
Not open for further replies.
P

Physis 3

Guest
I'm looking at a Coleman 1850 watt generator. I'm sort of trying to backward engineer this thing in order to find the problem.

This is the design:

[1] 2 armeture coils.

[2] Coils are on either side of the armeture and shunted by two components. Ones either a capacitor or a MOV (I doubt it's a MOV, although it does look like one), the other looks like a diode but doesn't have a standard anode marking, so maybe it's a resister or something else but it's case looks like a silicon diode.
(I can't see the markings on these thins and I haven't removed these yet to get a better look because it wont be that easy and I'm douting that's where the problem is.)

[3] There are no brushes on the armeture.

[4] The iron cores of the armeture and the stator or field coils are either laminated or uncoated layers and are continuous around the circumferance in the case of the field or stator.

[5] There are three stator or field coils. One for the rectifier for 12 volts DC, one for 125 volts AC (?) and one that goes only to a 7.5 uf capacitor.

All the components check out OK. Although there is some kind of case damage on the capacitor and it doesn't seem to hold a charge long, The problem I'm having is understanding how you can expect to induce current in the absence of a magnetic field. As far as I can figure you'll either have to feed some power to some coils to "start" a magnetic field, and there's no means in the design to do that, or have some permanent magnets.

Lamenated or iron plates, in my experience, aren't used for permanent magnets.

I'm really baffled by this. At this point, all I can think is that it never should have worked in the first place. My best guess is that the permanent magnetic fields were lost but I wouldn't expect permanent fields from what's there. Or the 7.5 uf capacitor is damaged but those things don't make a magnetic field out of nothing. And the best I know is that I was the first guy to disassemble the thing.
 
Last edited:
I've heard of self-excited generators that sometimes have to be zapped in some way to restore a residual magnetic field. This would likely be in a service manual.

Is this a stationary or portable generator? If the latter, I wonder if connecting connecting a 12v battery might help. (If the former, there would already be a starter battery.)
 
No manual available at the moment Larry. It's a pull string starter so it doesn't use any battery. I was thinking of attaching a 120 v. sourse to it's output to make it think it's operating and maybe get a field going.
 
Physis 3 said:
No manual available at the moment Larry. It's a pull string starter so it doesn't use any battery. I was thinking of attaching a 120 v. sourse to it's output to make it think it's operating and maybe get a field going.
Okay, so it's basically a magneto, and it does require a load current if it's going to self excite. Let us know.
 
Physis 3 said:
I'm looking at a Coleman 1850 watt generator. I'm sort of trying to backward engineer this thing in order to find the problem.

This is the design:

[1] 2 armeture coils.

[2] Coils are on either side of the armeture and shunted by two components. Ones either a capacitor or a MOV (I doubt it's a MOV, although it does look like one), the other looks like a diode but doesn't have a standard anode marking, so maybe it's a resister or something else but it's case looks like a silicon diode.
(I can't see the markings on these thins and I haven't removed these yet to get a better look because it wont be that easy and I'm douting that's where the problem is.)

[3] There are no brushes on the armeture.

[4] The iron cores of the armeture and the stator or field coils are either laminated or uncoated layers and are continuous around the circumferance in the case of the field or stator.

[5] There are three stator or field coils. One for the rectifier for 12 volts DC, one for 125 volts AC (?) and one that goes only to a 7.5 uf capacitor.

All the components check out OK. Although there is some kind of case damage on the capacitor and it doesn't seem to hold a charge long, The problem I'm having is understanding how you can expect to induce current in the absence of a magnetic field. As far as I can figure you'll either have to feed some power to some coils to "start" a magnetic field, and there's no means in the design to do that, or have some permanent magnets.

Lamenated or iron plates, in my experience, aren't used for permanent magnets.

I'm really baffled by this. At this point, all I can think is that it never should have worked in the first place. My best guess is that the permanent magnetic fields were lost but I wouldn't expect permanent fields from what's there. Or the 7.5 uf capacitor is damaged but those things don't make a magnetic field out of nothing. And the best I know is that I was the first guy to disassemble the thing.

Heres something you may want to check out.
http://www.endtimesreport.com/dead_gen.html
 
Sam, where you been?

Sam, where you been?

Are you sure this thing does not have slip rings on the rotor? This is the classic way to excite the field magnet of an alternator.

Automotive generators (not alternators) depend on the residual magnetism of the iron in the field coils. In fact, they must be polarized in order to provide the correct polarity. Maybe you have a similar setup.
 
OK Sam,

OK Sam,

You must have a brushless alternator. See:

http://en.wikipedia.org/wiki/Alternator

As I understand it, the exciter field coils are in the stator. As the armature rotates, the residual magnetic field generates an AC voltage which is rectified to drive the rotating alternator field coils. An AC voltage is induced the the alternator stator coils, and this is rectified and regulated to drive the exciter field coils. Of course, there is plenty of AC left over to drive the load.

Your residual magnetism needs a boost maybe.
 
My neighbor was a service tech at Coleman for 10+ years. He says it could be the capacitor, but usually it is the stator. Bring it here to the mfg plant and you may get a very low priced repair done on it. Maybe nothing. Depending on how old it is and if they have some spare parts sitting around.
 
Hi Rattus, it's good to type with you again. :grin:

I'm sort a thinking the same thing about residual magnetic fields. There is no connection to the magneto or any other source with respect to the generator section, no brushes, slip rings or anything else.

Let me ask you a couple things Rattus. Looking at the armeture there're what look like diode across the coils on either side. Both coils and what may be diodes measure about 20 Ohms in either direction. I'm figuring it's gonna need a DC component in order to keep a magnetic field. AC will just demagnetize things. Diodes could satisfy the need for DC but getting the same measurement in either direction suggests that these gadgets either aren't diodes or are perhaps open. What are your thoughts on this as a design and a potential failure?

And if this thing needs to be remagnetized how would you handle it?
 
Sam, I think the armature carries two sets of windings: A DC generator as in the old cars but with rectifiers instead of a commutator. The second winding is the field winding of the alternator, and it is driven by the rectifier output.

The stator also carries two sets of windings: The alternator output which drives the field (through a rectifier) for the DC generator. Then there will be some sort of voltage regulator.

Your diode measurements may be shunted by the windings. You must make sure the diodes are isolated.

It is likely to be more complicated than this though, so I could not make any recommendations without seeing a schematic.

I would suggest trying one of the polarizing methods found in the links already posted.

I used to start balky PE-75s by jumping a Jeep battery to the exciter, but you don't have any slip rings!.
 
Well, let's address each item in order Rattus:

[1] Yes, 2 windings on the armeture.

[2] No commutator and no rectifier external to the mover other than the 12V. output. Although there are the devices that look like silicon diodes internal on the armeture that I've yet to pull out to identify and test.

[3] No form of regulation, at least that I've identified. And I don't mean, "there's something I haven't seen".

[4] "I must make sure the diodes are isolated". Thank you Rattus:grin:

[5] Schematic, yeah, that would certainly be cool.

[6] Exiting a magnetic field externally is something I'm considering. Except 12 V. wont work here. Like I've mentioned, I'm considering back feeding 120 VAC to it.
 
Mrat, I've just read the link you provided and it seems like it might have the potential to solve the problem. I'm sorry I haven't had the time to read it sooner but thank you and I'll post back with whatever the results are.
 
Jim Mac

Jim Mac

Try flashing it with a 12 volt battery. Plug in a 120 volt cord with with the female end cut off. Keep the ends of the cord seperated, start generator, take 2 - 6 volt lantern batteries and connect the two in series. With generator running connect one end of cord to minus terminal and quickly and briefly swipe the other cord lead across the positive terminal. Be careful because the cord will will be energized with 120 volt AC, if this corrects the problem. Good luck
 
Status
Not open for further replies.
Top