Coleman Powermate low voltage

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Hello, Forgive me if this post is Off Topic, I cannot seem to find any sort of generator newsgroup, I posted this on alt.rv but I have not had any responses...
I have a Coleman Powermate 1850 MegaPulse Generator Model PM0401853 which I am trying to help my father-in-law fix. Unfortunatley I don't have any sort of tachometer to check the speed but it starts easy and sounds right and I really don't feel that there is anything wrong with the gas motor itself.
So, I assume that my problem is in the generator side of things, it will only give me about 90 Volts @ 60HZ. Because the Hz is right I assume that the RPM's are correct, so why am I only getting 90 Volts?
If I manually overspeed the motor (and it really sounds like it is running too fast when I do this) I can get 120 Volts BUT the frequency is about 70 Hz (which again leads me to beleive that the engine speed is too fast). This is frustrating because if I had a bad diode or a bad winding I would think it would not work at all. But I cannot think of a reason that I would get low voltage at (what I assume to be) the correct RPM.
Some research on the internet let me to un-solder the diodes on the rotor and according to my voltmeter they are okay. What I need to know is what Ohm readings I should get on the rotor windings as well as on the different windings in the stator. Also, according to my voltmeter the capacitor is okay. The only manual I can find for this generator on the internet is the owners manual. Anyone with a techical manual for this generator perhaps you can help out...
Thanks in advance
Craig
** Follow UP** the folks at Powermate think it is a diode problem (unless I am using my voltmeter wrong, I already checked them).
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What kind of meter are you using to measure the voltage? Does it measure the correct voltage level from the power company? Could the meter be confused by the saw tooth or square wave out put of most gensets vs a pure sine wave?
Steve
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And what are you using to measure the frequency? There aren't a lot of home-handyman instruments that measure frequency. I'm also thinking that your measurements may be misleading because of waveform.
What is it that leads you to suspect that the unit has a problem? Do things not work when they're plugged into it?
Chip C Toronto
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I'm learing a lot here, thanks for that. As for the sine-wave problems I have no idea how to address them. I have been using a digital volt meter to check everything (except the frequency), I have an older analog meter that I can use if that will yeild different results. The ONLY thing I have that shows frequency is a little electricity use gizmo called a KILL A WATT, not as good as something else but it is the only thing I own that shows frequency. As for things working right, any sort of light bulb seems dim (I have been using a 300 watt shop light for testing purposes). The generator is a brushless style and in fact won't show any voltage until I place a load on it, so I plug the light in one socket and my DMM probes into the other. I am hesitant to start pluging stuff in if it is not working right, I don't want the low voltage to dammage something (but, maybe it wont).
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the generator is probably low voltage cause engine running slow, they are VERY noisey at running speed. frequency of square wave probably confuses kill a watt.
I bought one of these generators for 50 bucks off craiglist for a buddy of mine. he adjusted one govenor spring that was stretched and it warks fine
try some standard light bulbs to test voltage.
frequency doesnt matter for most stuff but does mess with clocks etc
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That's why I suggest a cheap toaster, or a lamp with filament bulb. My guess is, you're over analyzing the problem.
If you don't think you're over analyzing, I'll give you several other options.
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Christopher A. Young
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wrote:

I'm learing a lot here, thanks for that. As for the sine-wave problems I have no idea how to address them. I have been using a digital volt meter to check everything (except the frequency), I have an older analog meter that I can use if that will yeild different results. The ONLY thing I have that shows frequency is a little electricity use gizmo called a KILL A WATT, not as good as something else but it is the only thing I own that shows frequency. As for things working right, any sort of light bulb seems dim (I have been using a 300 watt shop light for testing purposes). The generator is a brushless style and in fact won't show any voltage until I place a load on it, so I plug the light in one socket and my DMM probes into the other. I am hesitant to start pluging stuff in if it is not working right, I don't want the low voltage to dammage something (but, maybe it wont).
I typically use (used to anyway, until it said "PF" and then nothing) a Kill A Watt to check the frequency of my generator before connecting them to my OutBack inverter system which will refuse to connect if the frequency is out of range (about 56-64 Hz, thereabouts). I typically set the frequency to about 63 Hz and it generally drops to about 59-60 when a load is applied. The generator you have is rather pathetic (I have one too) and if I recall it only ever put out about 100 VAC at anything over about 1000 watts. If you ask me they are lying about the output. If the diodes check out OK and the field and stator coils are not open then I suggest increasing the engine speed until you get 63 Hz which will probably be around 130 VAC. Until you attach a load.
The good news is that for half the money you can get a cheap Chinese generator (UST GG2300) that really does produce 2000 watts and lasts about 10 times as long. It's a little bit bigger and noisier though, but not real loud.
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I'm using a Craftman Digital volt meter for the voltage. And a P3 Kill A Watt for the frequency (I don't have anything else to read frequency)
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Pumbaa wrote:

Does the voltage remain low when connected to a load?
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Good question. In fact the voltage reads 0 until it is connected to a load. As I understand it, this is due to it being a brushless style generator.
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Try alt.energy.homepower many there know generators, but if its 60hz, rpm is probably correct at 3600.
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Some inverters put out modified sine, which reads about 90 volts on a digital meter. My suggestion is try a filament lamp of some kind, or maybe a hair dryer. Old style toaster, is also good. If the toaster works, you're likelly getting modified sine. And the machine is OK.
I have an ETQ which has really done a good job. Never checked the voltages. It runs a toaster (Yes, I really did plug in a toaster, and try it.) Also runs a furnace, guy I knew had his power out, couple years ago. The ETQ ran his furnace nicely.
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Stormin Mormon wrote:

Ah, good catch! If the generator is putting out a modified sine wave and the meter is measuring peak-to-peak, there's gonna be a difference.
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Why would a single phase generator be putting out a square wave? I imagine it may be somewhat fuzzy, but I think it pretty much has to be a sine wave.
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It's incredibly unlikely that a small generator would put out square wave, or mod sine. It's so much easier for a small, inexpensive generator to spin a coil, and produce natural sine.
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On Jun 24, 2:43�pm, "Stormin Mormon"

a buddy put several generators on a techtronics scope, none were nice sine waves like the power company provides
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somehow someone was talking about inverters,which can either output square wave,modified or quasi-sq.wave,or sine wave AC.
Why it came up about generators,I don't know. An AC generator is always going to output a sine wave.
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Jim Yanik
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I'd think so, at least the spinning coil ones. Honda has some that have "inverter technology". Maybe the guy with the oscilloscope is picking up some harmonics, and other noise.
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http://www.hondapowerequipment.com/products/generators/content.aspx?asset=g g_inverteradvantage
the generator makes "multi-phase AC",converts to DC,then uses an inverter to get back to 60hz AC.
it's very possible it makes a lot of electrical noise.
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Jim Yanik
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You guys lost me. A Coleman is not a Honda inverter generator. Besides that, Honda claims their sine wave is better than what you get from your local utility.

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