Coleman generator model PM0555523 only have 1.9volts output

Hi,
I couldn't find anywhere to get a wiring diagram for any models of Coleman Powermate, they are out of business. Not to worry, I've repaired LOTs of generators so I'll use this answer as a general one for how to troubleshoot "no output" problems and refer to it in other answers. My apologies for the stuff that doesn't apply to your situation.

The first thing to know is that portable generators have to be run with some kind of load about once every 3 months in order to keep working. So if you've stored your generator in the shed for a couple of years it may just need to be flashed. If that's not the case the rest of this procedure applies.
I'll write one of these about how to flash a generator when someone asks for it on FIxYa :-)

If the engine runs more or less as it always did, we can eliminate it as a problem. If it ran more slowly than it is supposed to it would be a problem. If it ran but sounded like it was loaded even with nothing plugged in that would be a different problem. It should run at just over 3600 rpm just like a lawn mower.

Looking at the back end of the generator you'll find a plastic squareish cover held in place by 4 long bolts that run all the way thru the generator, this is the endbell cover. Get out a 7/16 box end wrench and a socket and remove the 4 bolts, there will sometimes be a ground wire and lug on one of them that you just move out of the way. Gently pull the cover off if it doesn't fall right off the end of the generator, there may be wires connected from the endbell cover to the windings of the generator. There may also be a set of graphite brushes sticking out of the endbell cover. Look at the wires that come out of the part of the generator that doesn't move (stator), there will be at least 2 and most likely 4 of them that are larger and go off to the outlets of the generator. Look for obviously broken wires. You can check these power windings of the generator with an ohm meter, on the 4 wire models you should find that there are 2 sets of 2 wires that measure less than an ohm with no connection between them, none of the stator winding wires should be connected to the generator frame.

Looking at the end of the generator you will now see one of 3 basic ways of building a generator;
a) nothing at all connected to the rotor part of the generator, and a capacitor with 2 wires that go to a winding on the stationary part of the generator. This is a brushless generator.
b) a flat plastic plate connected to the shaft of the rotor with 2 metal rings in the surface of it. There will be 2 brushes in the endbell cover under a little PC board, and 2 wires will run to a winding on the stator.
c) a brush holder assembly that has 2 brushes riding perpendicular to the rotor shaft on 2 metal slip rings. There will be wires connected to this assembly, on some models these wires go directly to the windings on the stator, on others they connect to a voltage regulator module.

If this is a brushless model, check the capacitor first. You can visually inspect it for cracks, obvious damage, broken wires and so on but the only definitive test is to get a meter and measure it. The value in microfarads will be written on the side of the capacitor somewhere.
If the capacitor was good, look at the diodes and movs located on the rotor itself. Usually these are tucked into 2 little slots in the plastic frame that the rotor winding wires wrap around. If you don't see any visual damage like broken wires, burned parts, etc. You'll have to unsolder one end of each of the diodes to test them. Just unsolder one end and unwind the wires for the 3 parts that connect together (winding, diode, and the mov behind it), this keeps us from getting the diodes back in the wrong direction later. Use the diode function of a DMM to test the diodes, check the rotor windings with an ohm meter (should be tens of ohms from the disconnected wire to the other end of that diode) and check that the mov(s) aren't shorted.
If all of that stuff checked good, put it all back together and try flashing the generator.

Generators with brushes:
On both types of brush arrangements above, examine the brushes themselves first. They have to be long enough to press against the slip rings. Also look closely at the slip rings themselves, under normal use they'll become dark and a little worn but too much junk on them is enough to keep the generator from making its rated power. Clean them with a bit of fine emery if they are dirty and the using an ohm meter measure from one slip ring to the other, you should get something between 10 and 100 ohms depending on exactly what pawer rating your generator has. The main things to look for are that the rotor winding you're measuring is not an open circuit and isn't a dead short. Also measure between either slip ring and the shaft or the rotor, you should get an open circuit.

On those models with a brush holder assembly you'll need to remove it to do the above checks. Mark it first with a Sharpie or other pen so that you'll be able to get it back in the same direction it came out, then using a 9/32 socket or nut driver take the bolt out of it. Be careful as this is not a good bolt to break off. On all brush assemblies look for evidence of melting of the plastic housing, when this happens the brushes can't make proper contact with the slip rings.

If the rotor checked good, and the brushes looked good, we need ot check out the part that supplies the voltage to the brushes. On the models with a flat plate commutator ( case b above), there will be 2 (usually yellow) wires that come from the stator and go either to a plug on a pc board mounted in the endbell cover, go to a metal plate with 2 diodes mounted on it on these older models just disconnect the wires and check the diodes and the capacitor, check the stator winding too. On models with a pc board, unplug the wires from the board and check the stator winding. Next take out the 3 phillips screws that hold the board to the endbell and look for burnt or bad solder at the place where the socket pins go into the board. Other than visual inspection of the board there is not much on it that someone unfamiliar with electronic power supplies can test on it. Check for broken wires on the brushes themselves.
The only other thing to do on these flat plate models is to reassemble them, flash them, and see if that fixes the problem.

On models that have a brush holder assembly with just 2 wires going directly to the stator, mark and remove one of the wires on the brush holder then measure the resistance of the winding from the wire you removed to the other wire where it attaches to the brush holder. You should not see an open circuit, and this winding should have an open circuit to the generator frame (as in not shorted inside the stator). Resistance values of a few hundred to a couple of thousand ohms are normal for these windings. If all of that is good you may have a bad part on the brush holder assembly, like the pc boards above troubleshooting them is not for the untrained.

On those models with a voltage regulator module connected to the brush holder assembly, find the wires on the voltage regulator that go to the stator (usually a blue and red wire marked 4 and 6), and make the test described above. If that checks good remove one of the wires that go to the brushes and measure the resistance across the brushes, you should see a resistance that's almost the same value as when you measured across the slip rings earlier, if not the brushes are bad or misinstalled. As far as I know there is no way to repair the potted voltage regulator modules used in most small portable generators. If you've gotten to this point and a good visual inspection of the voltage regulator module hasn't convinced you it's burned of otherwise broken rate this answer and ask me directly for how to troubleshoot around the module they're expensive little buggers.

OK, if you've gotten this far you should have found something broken in the generator that you could replace, now you just have to figure out where to get a replacement part for your particular generator.
I know a little about that too but I'll insist on having to be asked.
If you got this far and found that you've got a broken rotor or stator my advice would be to go look for another generator if possible. It isn't hard to change out either of them really, but it does require skills that are best taught in person by someone who has done it before.
If you got this far and haven't found anything broken, you can ask me directly and I'll give you my best advice.

To ask questions of me directly you'll have to go to my profile and hit the "ask me" button I think.

Good troubleshooting,
Carl

How do u flash a generator