Mep005 Not Producing

[Old Man]

Yes, I have 24 volts dc at F1 and F2. I followed the directions in TM 5-6115-465-34 page 5-75. When I hold the start switch up I notice the voltage meter will climb up to about the 24 volt range until I release the switch. Anyway, after following the instructions in TM 5-6115-465-34 page 5-75 since after jumping across pins A and C on connector P37 I have 24 volts DC at F1 and F2 the problem should be the speed switch. But now I have replaced that and still nothing. Since I have 24 volts DC shouldn't that mean the voltage regulator is working properly? I will look for any broken wires tomorrow but everything still looks pretty new. This gen only has 54 hours on it.

 

[Guyfang]

If you have 24 volts on F-1 and F-2, you need to pull the rear cover off the gen set and then remove the end bell of the main gen. See if F-1 and F-2 wires are undamaged the whole way from one end to the other. I have found on a number of occasions, that one or the other wire was pinched/cut someplace. If they are good, then you need to test the exciter stator, located in the bell housing end cover. If that's good, you need to look at the diodes on the rotor.

If you have 24 volts to the exciter/stator, (via F-1 and F-2 wires) and the stator is good, and the diodes are good, that main gen should put out voltage, IF the windings in the main gen are good. You can excite the main gen with two flashlight batteries, if everything is in order.

 

[Old Man]

Ok, I will look at those things today. Funny you should mention the flashlight batteries. I was already going to ask you about an idea I had. If I took a 24volt dc transformer and fed the 24 volts into the 110 volt outlet and then started the unit would that lite off the gen? My thinking is if that worked wouldn't that narrow down the possible problems?

 

[Guyfang]

We were told in AIT that this was indeed something we could do to excite the main gen when all else failed. And in fact, one of my fellow CWO's did just that in El Paso. So give it a try. But if you have voltage on F-1 and F-2, there is nothing in between . Nothing to hinder the main gen from lighting off, IF the exciter/stator is in order, the diodes and the windings.

 

[Old Man]

Well I couldn't find a 24 volt dc transformer locally so I took my 18 volt cordless drill battery and fed that into the 110 volt receptacle and started the engine. Still nothing. So I guess that means I'm going into the end bell. Unless I find something obviously wrong there should I replace the diodes next? I did read a post on another site that detailed how to do that. He said it is rather easy on the mep005. Is there a way to narrow it down to either the exciter/stator or diodes prior to replacing things?

 

[Guyfang]

Read the -34 book. I posted them in SS. It explains everything. And yes, I would call it easy to check. And repair.

 

[Old Man]

Well, just an update. It turned out to be a bad diode. Put a new set of diodes in, tested the old ones and sure enough one was bad. Its back to producing power just fine now. Guyfang I want to thank you for helping me with this. I would never have figured this out without your help. Thanks again.

 

[Guyfang]

That's what we are all here for. Help, or helping. Glad your problem is fixed. And yes, you could have figured it out. Might have taken a bit longer, but you would have found it sooner or later! Take care and have a nice sunday! Ours is about over, and looks like rain again.