MEP 803a failure

[EFR]

Pull the top cover. Look for hot parts and burnt parts, When you turn off the set, will the meter stay at 130%, or drop. Do you have 120 volts AC at the 120 volt outlet?

 

[EFR]

I got into the generator a little deeper today and I'm pretty sure I found the problem. The generator itself is fried.

Question: would I be better off finding a new surplus or rebuilt gen head? Is that what the electrical generating part is properly called? Is it easier to remove from top or front?

It looks like there are only 12 black wires from gen set to control, which are marked. Will a new genhead have the same setup?

Thanks for your continued help gentlemen.

 

[Guyfang]

I got into the generator a little deeper today and I'm pretty sure I found the problem. The generator itself is fried. (Well, lets not go overboard. The main generator winding are burnt, yes. But without testing, you do not know if the entire main gen is unserviceable. The exciter stator and exciter rotor may be good. So if they were, you might find someone who has a main gen that has burnt exciter stator/rotor. Its possible to make one out of two. )

Question: would I be better off finding a new surplus or rebuilt gen head? Is that what the electrical generating part is properly called? (It would appear that the civ world calls it that. In the milatary its a main generator.) Is it easier to remove from top or front? (Read the -24 TM. It tells you how to remove the main gen. Personally, I would pull the engine/main gen out as one part, and separate it on the ground. The TM explains how to do this.)

It looks like there are only 12 black wires from gen set to control, which are marked. Will a new genhead have the same setup? (What do you mean as, "New genhead"? A new, non military main gen? If so, it should come more or less looking like what you have. But finding one to fit properly may be not easy. Getting it rewound is pricy, but maybe a quicker solution to your problem.

Thanks for your continued help gentlemen.

 

[Guyfang]

Did you have the Quad winding fuse and varistor mod on the unit?
If you didn't maybe you just fried the voltage regulator and quad windings.

A member on here makes a direct replacement VR that works with fried windings

You have this backwards. The Quad MWO is not intended to protect the VR. Its to protect the quad winding from a VR that goes into an over volt condition.

 

[Guyfang]

No. Factory as it came from the Pennsylvania depot

You do not understand what was asked of you. The Quad MWO, Modification Work Order) was installed, or suposed to be installed, to correct a problem that the Army did not want to fix. The problem is that a VR, (volt reulator) can go into an over volt situation, and fry the quad winding. The MWO was installed by all levels of maintenance, but for some reason not all sets were upgraded. It was not done at the factory, and SHOULD have been done at the Letterkinny Depot, (Pennsylvania). So you need to check if its there. If you do not know what it is, look for it in the TM section, or simply open the control panel and take a picture. Post it here and someone will tell you if its there. Its simple to apply, takes a 10-15 min. The required parts and instructions are in the TM section.

 

[nextalcupfan]

You have this backwards. The Quad MWO is not intended to protect the VR. Its to protect the quad winding from a VR that goes into an over volt condition.

I wasn't very clear in my original post but I meant the Metal Oxide Varistor will protect the VR while the Fuse protects the generator head.
From my understanding the Varistor clips the voltage spikes that can damage the diodes in the VR.
I could very well be wrong though.

 

[kloppk]

I wasn't very clear in my original post but I meant the Metal Oxide Varistor will protect the VR while the Fuse protects the generator head.
From my understanding the Varistor clips the voltage spikes that can damage the diodes in the VR.
I could very well be wrong though.

Exactly correct

 

[EFR]

GuyFang:

Thank you very much. I know very limited about generator heads (or their parts, etc.). Your comments are quite helpful.

I just need time to pull it all apart and look. I have the TM's, but did not see (yet) to get the unit out of the case. It looks like a project. I'll look into the TM again for the relevant information. Once I get it apart, I should have a better idea of what exactly failed, and work on replacing same.

As for replacement, I'm hoping to use OEM parts/surplus.

Thanks,

EFR

 

[Ray70]

Looks like at a min. you will need to find a new (or used) stator. Post up some pics once apart and we can get a better idea.

 

[Guyfang]

Open TM 9-6115-642-24 to PDF reader page number 185. Start at Paragraph 3-6. Read it once. Then again, but decide if you want to pull the main gen and engine as one package, or just the main gen. After doing this one time, trying to just remove the main gen, I discovered that with very little more work, the whole package comes out just as easy, if not easier. You can also spend a bit of time cleaning things up, and getting to know your set better when it all comes out. You can also ignore some steps. Like draining engine oil. If your not going to open the engine up, why bother draining oil. You can also skip steps, if you think of ways to do the same step, without taking too many other things apart. This is not rocket science. Its just matter paying attention, and taking your time. The beast way to solve a problem is to divide it up in small bit, and solve the small bits one at a time. If you need help, or have a question, just give a shout.

 

[TrailLifeBill]

I just listed my 803 in the classifieds if you want a parts donor. It ran great for 3 storms (approx 50 hours since I bought it) and then blew a head gasket. I pulled the head, and there is more engine damage than I want to deal with - scoring on #1 cylinder and rod bearing. It was making electricity till I shut it down when the gasket blew. (I was doing a PM at 50% load and was at the control panel when the gasket blew.)

 

[EFR]

I've started to pull this thing apart. I have the housing pulld apart on the front of the machine. I do not want to take apart any more than necessary as there are a lot of wires and lines I don't want to screw up. Looking at the genhead, I would think the interior part would come out, making the unit lighter, and easier to remove the actual housing?

Does the central part (stator) come out? How is the housing removed from the motor?

I have downloaded all the manuals I could find, but found not much to help in this regard.

Thanks,

EFR

 

[Bluevic443]

You will need to put in some kind of lifting aid on the stator at the point you have it in now. I used an engine hoist. Lift the stator by the cable at the top. Remove the two mounting bolts that attach it to the skid. Put just enough lift to take the load of the stator, no more. It should now slide straight back. Will look like this when removed.

There are five bolts that hold the rotor plate to the flywheel. Again, use some form of lifting aid, these parts are heavy!!!


Will agree with everyone else that it is easier to pull it out as one piece.

 

[Guyfang]

Dude. Your killing yourself by not simply pulling the whole thing out. If you try and pull it apart as it is in your pictures, you are sure to screw something up. Its not that hard. Blue described how to do it. But in the set is a PITA.

 

[EFR]

Thank you very much Bluvic, that helps a lot. I'm hoping to avoid disconnecting all the wires, but it looks like I may have to. I am more concerned of miswiring than anything; hence my apprehension of removing he front cover, but I may have to. I started marking the wires with tape and a sharpie.

Thanks,

 

[Guyfang]

Keep in mind, marking wires can lead to miswiring. If someone else miswired something, you will just repeat that mistake. Every wire has a wire number stamped on it. Be sure to check the wire diagram in addition to looking at your markings.