MEP-003A problems

[spyderrls]

MEP-003A problems/ UPDATE PAGE 2

Looking for some insight guys.

Ok, I recently got my first piece of green iron, a MEP-003a generator I got from GL. It runs great and everything was there, as far as I know. But here's my problem, It doesn't make electricity! No reading on the voltmeter or hz gauge in any position, and regardless of where the voltage reconnect switch is. I verified this with a fluke digital multimeter. All I was getting was about .5 volts from the lugs and convenience plugs.

So I get to looking around at it. I noticed on the voltage regulator board it was missing the jumpers from terminals 1,2,3 and 4,5. According to the wiring diagram. But the screws were laying in the bottom of the cabinet. So I replace those and put in jumpers. Still nothing.

After that I started going through the manual. I did the procedure to check the VR. I removed the wires at TB3-6 and TB3-5 and connected a 12v battery per the manual. That got me the following, the load meter pegged all the way past 125%, I could get the hz to adjust to 60 and that stayed stable. And no reading on the panel voltmeter. Also, the voltage on the connection lugs checked as follows, with the reconnection switch in the 120/208 position.

L1-L0 15.75V
L2-L0 8.2V
L3-L0 6.3V
L2-L1 12.35V
L3-L1 21.8V
L3-L2 13.7V

Also, without the battery and hooked up as normal there is no voltage at TB3-5 and TB3-6.

So I'm not sure what this is telling me. Also, I checked all the rotating diodes and they all appeared to be fine. Im leaning towards this being a VR issue. However this is the first generator Ive ever messed with, and I'm not an electrical pro by any means.

So I was wondering if anyone had and ideas on which direction to point me in.
Sorry for the long read, but I wanted to try and get as much info in as possible. Much thanks in advance and any help is appreciated. We've got a winter storm with significant ice expected on its way soon.

Jason

 

[atankersdad]

Welcome to the site. You have come to the right place for help. Go to the forum that deals with Gen units and read 5 or 6 threads. You will immediately become aware that we have some real experts on these units and the second thing you will know is who they are by reading the valuable help they give fellow members. They helped me, they will help you.

 

[glcaines]

Have you tried flashing the generator? Sometimes I need to flash mine to get output, sometimes not. Simply turn the selector to the start position for a few seconds and see if it starts putting out. Sometimes I have to do this several times. Don't worry, the starter will not engage.

One note that is very important. Never, never, never let the engine idle. This will damage the VR. When the unit is putting out at 60 hz, simply shut it down. When you start it, the engine should come up to full operating RPM.

 

[spyderrls]

Yes, I have tried flashing the field. But that didn't get me anywhere. And also, Im aware of the problems of idling this set. I'm thinking maybe that's what happened before I got it. They should have known better, but maybe someone wanted a quieter gen for their unit.

 

[Speddmon]

First off, welcome to the site.

I'm assuming that you tried the test I have taken a snapshot of from the TM??



In the last sentence of that test it says, "If there is no output, the main alternator is bad."

You are not getting any output from what you posted, so there is something wrong in the generator head. With a battery hooked up to the two wires in the test, you are effectively replacing the voltage regulator and the bridge board with the battery. If the generator does not put out voltage like that, then the generator head has a problem

Right below that test procedure in the TM, it tells you how to test the rotating diodes. In the paragraph leading up to the test (inserted below) it tells you that the diodes being bad can lead to no voltage output or low voltage output.



From the test results I'm seeing in your post, I would guess you have a bad diode or two. That would be the place I would start. If after you check the diodes, and repair any bad ones if you find any. Let us know what's going on with it and we'll help you out.

 

[Speddmon]

OK, I just re-read your initial post....did you go through the test procedure for the diodes like the TM states? You said you are no electrical pro, so I'm curious if you are comfortable with your assessment of the diode conditions? If it's not the diodes, you could have problems with the field windings, the exciter field windings or the main alternator windings.

I'm leaning against there being a VR problem because you didn't get any output with the battery hooked up. It's not to say that you could have more than one problem (IE: generator head problem and a voltage regulator problem). But you have to get the generator head to start producing power first before you can worry about the potential of a voltage regulator problem.

 

[spyderrls]

Well I did get about 10 to 20 volts when I applied the battery. But that's a far cry from 120. I wasnt sure if for that test they were looking for the correct output, or just any at all. And yeah, Im no expert on electronics, but I'm pretty confident on the diodes. Had my grandpa double check them and he confirmed my readings. I'm alright on the basics. But that's about it.

I welcome any suggestions though on what to do and all the help is appreciated. Thanks!

 

[Speddmon]

I just thought of something else. When you did the battery test, did you have the battery hooked up the the right side of the wires? Meaning did you have them hooked up to the two wires going out to the generator head? And the correct polarity as well?

I wasnt sure if for that test they were looking for the correct output, or just any at all.

When you do the battery test you should see a considerably higher voltage than what you got in your test. And the voltage should be fairly consistent between the phases, meaning all the phases to L0 should be roughly equal, and the phase to phase voltages should be pretty equal. Yours are not, making me think more troubleshooting of the generator head is in order.

 

[rat4spd]

One note that is very important. Never, never, never let the engine idle. This will damage the VR.

Caveat, this applies when you have the exciter/VR energized. Otherwise the generator doesn't care what the motor is doing. Also, is the fuse for the DC circuit blown?

 

[jbk]

to check those diodes you will have to remove them or the wire. should have contin. in only one direction.

 

[atankersdad]

Help just arrived. No better than the above members!! I knew it would not take long Speddmon, rat4spd and JBK to help you. I sometimes just read their posts and wonder how they remember this stuff..

 

[spyderrls]

Ok time for an update, and a thanks to those who have tried to help! I finally got the right combination of good weather and free time to be able to work on this generator.

I got access to a KNOWN good voltage regulator from a functioning unit. So i swapped it out with mine temporally to maybe at least rule mine out as being bad. I know most of the people here have been leaning against the VR being bad, but i took the shot anyways. Here is what happened, fired it up and nothing had changed. It was in the 120/208 position. Shut it down and repeated the process in the 120v 1 phase position, same results.

Now here was the unexpected part, I repeated the shutdown and changed it over to the 120/240 1 phase position. Upon starting up, with the cb off, the percent of rated current gauge maxed out, the engine acted like it was bogging down with heavy black smoke, and the alternator started smoking heavily! All this happened within about 5-10 seconds and I shut it down immediately upon noticing this.

So what do you guys think this means? Is it a short in the alternator or is maybe the reconnect switch bad?

 

[Speddmon]

It's hard to tell....something is definitely shorted though. I still think something is going on with your generator head itself since you don't get the proper voltages out of it when you do the battery test like you did above. But, what you just described now, could mean you have multiple problems.

 

[spyderrls]

Found out yesterday this set wont run when you disconnect the batteries. It should shouldn't it? SO does that mean maybe there is something wrong with the 24v system that's not letting it energize? Or do I have a whole nother problem?

 

[Speddmon]

First off, yes it should run without the batteries connected. Secondly, NEVER disconnect the batteries while the set is running. The surge you created when you disconnected the batts, could fry the voltage regulator, and/or any of the DC components what are powered at the time of disconnection. If you haven't already damaged any of the DC stuff you are lucky.

Now, back to the original point of your post...if your set is not staying running, then your voltage regulator is not putting out. There is a thread I'll have to find it where I spell out the easiest way to test and check all of the components of the charging system.....I'll put it in this post as soon as I find it.

Edit...Here is the post I was talking about. Follow the instructions and find your problem...Testing the DC Voltage regulator.

 

[pmramsey]

An often over looked problem is the fact the control panel is grounded. If the ground is failing, the gauges deliver no or unreliable indications. Dismount the control box from the machine. Clean all connections including the ground wire and screw connection on the bottom of the box. Check for bent pins on the connectors. Reassemble as required. Disable fuses before dismounting the unit. When not in use, disable the two fuses on the front panels.