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Discussion Starter · #1 · (Edited)
Model PM0535202
Briggs engine

I just purchased this secondhand. I need help with the carb throttle adjustments. They were diddled when I got the generator. There are to adjustment screws. One appears to be the speed adjust. This end of the screw was missing the target tab. I bent the screw tab so it now aligns. I assume this is adjusted to set max RPMs. I also assume this needs to be set correctly.

There is another screw adjustment which I don't know what it's for. It's very difficult to see this mechanism. I may need to remove gas tank to see more.

^The throttle lever only moves a tiny bit.

I've tried to word this the best I could. I may have to remove gas tank and take pics.
 

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It would help if you post a clear picture of the following:

1. The complete throttle and governor linkages to see exactly what mechanism is being employed, and
2. The two screws you're referring to
 

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A few thoughts:

Is the engine running OK? Or do you sense it running rich or lean? Some carbs have adjustments for the fuel mix, some dont. The last engine I messed with those on was a 2 stroke Husqvarna 455 chainsaw. If these are the type of screws you are talking about - a service manual should describe a starting point for them. However, I am not sure how to find a service manual for your gen engine. You would have to find what the engine model is (not the gen) then search briggs & stratton to find the service info.

The throttle linkage (as OrlyP alluded to) is what will set your engine speed. Your engine speed will set your AC frequency - given this is a rotary generator (not an inverter). If you had an oscilloscope or an AC frequency reading multimeter (most don't show the AC frequency, just the voltage - fancier ones will show RMS - you need accurate frequency measuring). There will be a screw adjustment for a tensioning spring in the throttle linkage. This tensioning spring sets the governor and the adjustment screw is how you fine-tune the engine speed. This is not the same as a throttle on, say, a push mower where you have a lever to run through the whole RPM range of the engine. Your governor is designed to hunt for a constant speed - which on a rotary of this class is 3600 rpm.

For what it is worth, setting the RPM so your frequency is a tad high at no load is probably best. As you load the gen it can sag a bit. Electronics are able to handle a slightly high frequency better than they are able to handle a low frequency.

The above is especially true for running gasoline engines on natural gas. NG has less energy so it goes without saying that you won't get the same amount of wattage out of the gen. However, when you get up in wattage engines running on NG can sag a bit. If you tune the throttle a tad high you will have some head room. Better yet - load the gen with your anticipated high load then tune the governor/throttle linkage for correct frequency (60.0hz in North America). Then check at no load.

As to the voltage of the windings - check continuity through the windings. That alternator should be a split phase - so you have 2 hot leads and a neutral. Find those tap points in the windings and check continuity through each hot and neutral and through each hot. Both hots together should be 240v. Either hot to neutral should be 120v.

If the winding continuity check checks out then you need to follow the circuit and check the voltage regulation circuitry.

The above electrical checks would benefit greatly from schematics and service detail for the gen you have.

Good luck with it!
 

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Discussion Starter · #5 ·
A few thoughts:

Is the engine running OK? Or do you sense it running rich or lean? Some carbs have adjustments for the fuel mix, some dont. The last engine I messed with those on was a 2 stroke Husqvarna 455 chainsaw. If these are the type of screws you are talking about - a service manual should describe a starting point for them. However, I am not sure how to find a service manual for your gen engine. You would have to find what the engine model is (not the gen) then search briggs & stratton to find the service info.

The throttle linkage (as OrlyP alluded to) is what will set your engine speed. Your engine speed will set your AC frequency - given this is a rotary generator (not an inverter). If you had an oscilloscope or an AC frequency reading multimeter (most don't show the AC frequency, just the voltage - fancier ones will show RMS - you need accurate frequency measuring). There will be a screw adjustment for a tensioning spring in the throttle linkage. This tensioning spring sets the governor and the adjustment screw is how you fine-tune the engine speed. This is not the same as a throttle on, say, a push mower where you have a lever to run through the whole RPM range of the engine. Your governor is designed to hunt for a constant speed - which on a rotary of this class is 3600 rpm.

For what it is worth, setting the RPM so your frequency is a tad high at no load is probably best. As you load the gen it can sag a bit. Electronics are able to handle a slightly high frequency better than they are able to handle a low frequency.

The above is especially true for running gasoline engines on natural gas. NG has less energy so it goes without saying that you won't get the same amount of wattage out of the gen. However, when you get up in wattage engines running on NG can sag a bit. If you tune the throttle a tad high you will have some head room. Better yet - load the gen with your anticipated high load then tune the governor/throttle linkage for correct frequency (60.0hz in North America). Then check at no load.

As to the voltage of the windings - check continuity through the windings. That alternator should be a split phase - so you have 2 hot leads and a neutral. Find those tap points in the windings and check continuity through each hot and neutral and through each hot. Both hots together should be 240v. Either hot to neutral should be 120v.

If the winding continuity check checks out then you need to follow the circuit and check the voltage regulation circuitry.

The above electrical checks would benefit greatly from schematics and service detail for the gen you have.

Good luck with it!
Thanks for the reply. The continuity is about 3,2 ohms on each winding using a digital meter.. Now I'm thinking it's something else wrong. The 2 diodes are measuring infinity in both directions with digital meter. I'm thinking I need to find my darsonval meter to check them. My knowledge of this circuit is beyond me.
 

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Discussion Starter · #7 ·
Are you sure you're using "diode test" mode on the meter? When diodes fail, they almost always "short".
The diodes are ok. So I have one wining putting out 120V and the other winding 0v. The only components on the brush end of generator are the 2 diodes and a capacitor. I don't know if there any componets in other end of gen.
 

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If you get power from one leg but not the other, the rotor and any of its ancillary parts (diodes, capacitors, brushes, etc.) have nothing to do with it. The problem is isolated to that 2nd winding and/or how you're testing it.

Are you testing for voltage at the winding itself, Hot to Neutral, from inside the genhead back cover, or are you trying to read it from the receptacle?
 

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Discussion Starter · #9 ·
If you get power from one leg but not the other, the rotor and any of its ancillary parts (diodes, capacitors, brushes, etc.) have nothing to do with it. The problem is isolated to that 2nd winding and/or how you're testing it.

Are you testing for voltage at the winding itself, Hot to Neutral, from inside the genhead back cover, or are you trying to read it from the receptacle?
Measuring the voltage right at the leads coming out of gen.
Can I lose residual magnetism in one winding?
 

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Can I lose residual magnetism in one winding?
Nope.

Residual magnetism resides on the rotor. The rotor produces the field excitation to energize both stator windings (Leg1 and Leg2). If you get power from Leg1 but none from Leg2, it means that the problem lies with Leg2.

Do you see any burnt-looking windings on the stator?
 

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Discussion Starter · #11 ·
Nope.

Residual magnetism resides on the rotor. The rotor produces the field excitation to energize both stator windings (Leg1 and Leg2). If you get power from Leg1 but none from Leg2, it means that the problem lies with Leg2.

Do you see any burnt-looking windings on the stator?
no
 

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I looked again today and nothing looked over heated. All the windings have a uniform color.
Can you take detailed pictures of the following:
1. Detailed pics of the stator windings
2. Test points for Leg 1 and Leg 2

Do any of the rope wrapped around the stator appear to be broken or cut?

If I take it at face value, it seems that one leg of the stator is open.
 

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Discussion Starter · #14 ·
Can you take detailed pictures of the following:
1. Detailed pics of the stator windings
2. Test points for Leg 1 and Leg 2

Do any of the rope wrapped around the stator appear to be broken or cut?

If I take it at face value, it seems that one leg of the stator is open.
View attachment 12744
View attachment 12742

View attachment 12741

The string wrapping the windings are fine.

Resistance and voltage readings were taken at the squire white plug in last pic.

How does the field coil and stator come off? They seem stuck and I don't want to force it.




Light Automotive tire Wood Motor vehicle Electrical wiring

View attachment 12754
 

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Discussion Starter · #19 ·
Start at 6:48 below and it should take you to the stator removal part.

I remove the field winding and all wire looks good. Nothing burnt or discolored. More pics attached. I can not see where the two armature windings are connected together.
 

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How many wires came out of the stator? I can see 4 inside the white connector... 2 Black and 2 White wires.

If I'm not mistaken, each Black-to-White pair is a 120V leg. Do you have resistance readings for each pair? Typically, you should see 0.3-0.5 Ohms. Otherwise, their resistance values should be close to each other.

Do you get any continuity/resistance reading between Black-to-Black and White-to-White? If the windings are isolated from each other, these should be open.

Check also continuity/resistance between each of the 4 wires to ground (ie. stator core). These should also be open.
 
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