Mep-003 Putting out 300 VAC and stalling

[Davon]

So this morning it is putting out 260 vac and it does respond to the voltage regulator knob. The T1 transformer had 45 vac between the two outer pins and 22.5 to the lower pin from each of them. I also checked this at the board. It's a little cooler here today. Maybe some poor connection that is a little better when it's cool. I guess I'll try to figure out all of those coils in CVT1 and see if they are getting the correct voltage inputs. Any help on this or other thoughts appreciated. In my mind CVT1 is either not getting the correct voltage or not putting out the correct voltage since I had only 5Vac on pins 14-17 and on my good generator I had 12 vac on these same pins.

 

[Ray70]

Something else you might try if you haven't already, unscrew the connectors on the back of the AC reconnect box as well as the control cube, separate and reconnect all of the connections incase you've got a bad connection on one of the pins. Look for any signs of corrosion while you have them separated.
If you have electrical contact cleaner you might as well clean / lube them while apart.
Definitely sounds like an intermittent connection somewhere.

 

[Guyfang]

Thats why I try to use serrated washers when bolting that box down. It was always a problem with grounding. And the Electric fuel pumps and the bracket they are mounted on. Serrated washer help there also.

 

[Davon]

I checked voltages at H1-2, 3-4, and 5-6 on my good generator and had 8, 12, and 15. On my bad generator they were between 12 and 15 vac. The good generator has an output of 12 vac between c1 and c2 while the bad one has 5 vac. I checked it at the CVT1 to rule out a bad connection downstream and had the same measurement. I have concluded that the CVT1 is bad and am working to swap it out. Hopefully I am correct

 

[Guyfang]

This is a job, that you need to take your time with. If you do not have enough time to do it, or do not think you do, do it in the morning. Get the wire diagram printed out and USE it. Do not just mark wires and wing it. If someone before you miswired it, you just repeat the mistake when you mark wires. Do take the time to clean out the AC box, while you are in there. Put on some good jams and take your time. No beer until it works.

Also, the wires are often secured with concrete. I mean they can have corrosion from hell on them. Reef them too hard, pop goes the Wiesel. You break off a terminal.

 

[Ray70]

A little trick I learned is that the plugs are secured to the back of the box with screws and nuts.
It is helpful to disconnect the plug with the main wires that loop through the CVT but it's very difficult to get your hands in there to reinstall the nuts.
The holes in the connector are the perfect size to tap to a 10-24 or 10-32 thread, allowing you to simply screw the connector back on with machine screws from the outside.
Hopefully your AC select switch has threaded tabs rather then screws and nuts as the threaded tabs are much easier to deal with.

 

[Davon]

Swapped out the transformers with no change. I'm not really surprised. On the working generator I did find that I have 50 vac at wires 14 and 17 if I disconnect them. On the bad gen, I have 25 vac when they are disconnected from the board. I guess I need to look upstream of the transformer? It's definitely not clear to me.

FYI, I just put the bad genny's transformer in the good genny to save time. Still spent all day at it.

Any suggestions?

 

[Davon]

Ok, so finally I figured it out. At least why it isn't able to regulate the voltage. Not how to fix it. I discovered that it isn't putting out 3 phases from the generator. If I measure from TB2-1 to TB2-2 I get 0 volts AC. From TB2-1 or TB2-2 to TB2-4 I get 150 VAC. That tells me that TB2-1 and TB2-2 are getting the same phase from the generator head. Not sure how that's possible. I started taking the generator head apart but didn't get to far. Any thoughts? I'm wondering if this generator is worth it. I need to get a new throttle for it and a fuel line. It's only got 120 hrs on it but it's on a jury rigged base. Happy for your input. Glad I at least figured out why CVT1 wasn't putting out the correct voltage even though the inputs were high. I think H1-H2 and H3-H4 were likely cancelling each other out or at least not increasing the voltage like they were supposed to because they were the same phase. Kinda feel stupid I didn't find this earlier on, but I guess I learned a lot more about the voltage regulation this way.

 

[Ray70]

Well, unfortunately I'm not an expert on the generator head itself but I'd imagine the TM can help you determine how to test the windings correctly.
If you decide to fix it up, I have a parts 003 here in RI with a good generator and skid base. it's essentially a complete machine other than I used the AC reconnection box, blower wheel and a few other small items on other machines.

 

[Davon]

Well, I wasn't as smart as I thought I was. After checking measurements on my other generator I didn't feel like I could blame it on the generator head after all. It looks like the head puts out split phase and the boards/diodes convert it to 3 phase if that is selected. I don't get why there is lower voltage going to pins 14 and 17 on the VR board but I don't know what else to try/check. I swapped out every part I could other than the head and spent hours figuring out the wiring diagram best I could. Now on top of this my other generator is cranking hard, but maybe I should make a seperate post for that. It's like the motor is just hard to turn over. Maybe I should put the motor from this high output generator on the hard cranking one?

 

[Guyfang]

If you do start anything with the second gen set, please do start another thread.

 

[cuad4u]

My 003A has a similar issue. When I start the engine in single phase 120 / 240 position I get 300 volts (on the panel meter and on a Fluke meter) for around one minute then it settles down at 240 volts and it stays there as long at it is running. The engine does not overload or cut off. When I put a 12KW load on it, it still holds at 240 volts as long as I keep the 12KW load on it and it does not go back to 300 volts until I shut it down for several hours. Then it goes through the same issue again. Not trying to hijack the original threat, but my problem is similar to the original poster's problem.

 

[Davon]

My 003A has a similar issue. When I start the engine in single phase 120 / 240 position I get 300 volts (on the panel meter and on a Fluke meter) for around one minute then it settles down at 240 volts and it stays there as long at it is running. The engine does not overload or cut off. When I put a 12KW load on it, it still holds at 240 volts as long as I keep the 12KW load on it and it does not go back to 300 volts until I shut it down for several hours. Then it goes through the same issue again. Not trying to hijack the original threat, but my problem is similar to the original poster's problem.

I am curious what voltage you have between pins 14 and 17 on the voltage regulator board when it is running.

 

[Triple Jim]

It looks like the head puts out split phase and the boards/diodes convert it to 3 phase if that is selected.

No, it's a 12 wire generator, and those wires are connected as needed to get 3 phase or single phase power.

 

[Davon]

No, it's a 12 wire generator, and those wires are connected as needed to get 3 phase or single phase power.

Ok, you probably are right. That was what I expected, but when I started testing voltages coming from the head when it was set to three phase I changed my mind. Not that it's always reliable, lol. I can't remember exactly how I concluded that. Regardless, I did finally swap the whole control box over from my other generator and it works! So, I guess it is something in the box. Now I have to figure out which part still since all of the parts that seemed to affect voltage tested normal per the manual and I already swapped out the VR board. I am wondering if the VR rheostat is testing normal by ohmmeter and failing when it has current going through it.

On another note, the generator that I thought was starting too hard due to friction was actually a bad connection and fairly new batteries that seem to be failing. So, my generator situation is not as hopeless as I had convinced myself it was.

 

[Davon]

Well, stupid thing is it was T2. I was poking around in the box with an ohmmeter and found that the windings on one side of it were open. Still confused how I missed that initially because I checked voltages on both sides?! Anyways, glad to have it figured out finally. Wish I hadn't made it so hard to figure out though. I did sub it with the other generator's T2 and confirmed that it doesn't put out 300 vac then