Mep-003a not producing power

[lukewright]

I recently purchased a second mep-003a after loving the first one. I purchased this one very cheap because it had been setting in the weeds for a few years and didn’t run. In only a few minutes I was able to get it running and it was producing power but as I would increase the throttle it would produce to much power. I took the main control box off my good generator and put it on this one i was having trouble with and it worked fine with the good box. I replaced the ac voltage regulator in the bad box and I also changed the exciter bridge rectifier assembly in the distribution box because I’ve heard those go bad as well. After all that it will not produce power at all anymore and I’m out of ideas. Any input is appreciated.

 

[rickf]

The very first problem I see is that you just guessed at the problems and threw parts at it instead of following established diagnostic procedures. That may sound a bit harsh but the fact of the matter is that those diagnostics are there for just this reason, so you do not go off on a wild goose chase. Once you start throwing new parts into the mix you can mask the real problem and that in turn will cause even more problems down the road. I strongly suggest you get hold of the manuals and go through the procedures, with the original parts back in place.

 

[Ray70]

Did you test it between changing the original VR and changing the bridge rectifier?
If not I think you need to back track and determine if you have a bad/incorrect connection somewhere or if you installed a bad part.
What did you use for a VR, an OEM or something like Kurt's upgrade VR?
If you used an original, are you sure it's a good one? Were all the jumper bars in place ( which are almost invisible unless you know to look for them ) and are you sure the wires are on the correct screws?

If all above checks out go to the rectifier... same thing are you sure its good and connected correctly?

If in doubt, on either part, swap out the control panel again and retest.
Then swap out the AC box and retest.

You need to have a game plan to test systematically to take 1 variable out of the mix at a time in order to isolate your issue.

Could be as simple as a bad connection or even forgetting to attach the ground strap under the control box.

 

[msgjd]

After all that it will not produce power at all anymore and I’m out of ideas. Any input is appreciated.

with other kinds of machines i have done the same thing as you , tossing in known good parts but unknowingly having a hidden problem deeper within .. A lot of us have done it, and if it turned out to be the wrong move we regret it . Usually our expedient action is due to time constraints and production demands, you need it to work and you need it now.. However, rickf above is right, and i have to concur with him .. I have yet to have any issues with my 003's other than a bad frequency meter recently, thus i cannot help you with your direct issue.. I am offering you luck and to point out the "manuals" (TM's) can be downloaded for free here https://steelsoldiers.com/forums/generator-and-electrical-tms.121/

specifically ; https://steelsoldiers.com/threads/all-the-tms-you-need-to-work-on-the-mep-003a.155936/
You should make sure you thank guyfang on here for them (and other guys for other stuff wherever applicable).

 

[Guyfang]

You wrote:
recently purchased a second mep-003a after loving the first one. I purchased this one very cheap because it had been setting in the weeds for a few years and didn’t run. In only a few minutes I was able to get it running and it was producing power but as I would increase the throttle it would produce to much power. I took the main control box off my good generator and put it on this one i was having trouble with and it worked fine with the good box. (You should have stopped here, and tested it several times. Even load it up. Why, just to make sure that the problem IS in the control box. Then, Start reading the TM.) I replaced the ac voltage regulator in the bad box (I assume that you put the "Bad" control box back on the original gen set? Wasted time. Should have left the good box on the gen set, and replaced the "good" VR with the suspected "Bad" VR. and I also changed the exciter bridge rectifier assembly (Wasted time. You have already established that the problem is in the control box.) in the distribution box because I’ve heard those go bad as well. After all that it will not produce power at all anymore and I’m out of ideas. Any input is appreciated.

There is not much more in the control box to look at. T1, T2, and the S1, start switch. That is what sends the voltage to the Main gen to excite it. I think pin 27 on the S1 is what sends the voltage down to the VR and to the excitation system, AND T1 and T2. Should be 24 volts. So, I would look for DCV on pin 27, during start up. Then I might just put the known good control panel, with the known good VR in it, back on your problem child gen set, start it up and see if it make good voltage. Then put the suspected "bad" VR in the control box. Start it, see what happens. Works? Then try T1. Then T2. Then write back and tell us what is what.

 

[Chainbreaker]

... After all that it will not produce power at all anymore and I’m out of ideas. Any input is appreciated.

With generator off, as in not running, have you exercised the "AC Reconnection Switch" back & forth to clear any oxidation on internal Reconnection Switch contacts? If it doesn't want to switch over, gently rock it back & forth with increasing pressure until it comes free & breaks over to latch in the other positions. If it won't... don't gorilla twist it as you can break it. There is an older thread on how to loosen the screws/nuts internally on that wafer switch to get some free play within the contact wafers to free it up & spay contact cleaner on contacts if required.

A bad or erratic AC Reconnection switch can cause intermittent AC output issues. I would pull the cover off the front below the load terminals & peek inside. After all...you said this genset was sitting off in the weeds. So, mice could have done some damage inside as they love to explore that box & nest in it.

 

[lukewright]

I recently purchased a second mep-003a after loving the first one. I purchased this one very cheap because it had been setting in the weeds for a few years and didn’t run. In only a few minutes I was able to get it running and it was producing power but as I would increase the throttle it would produce to much power. I took the main control box off my good generator and put it on this one i was having trouble with and it worked fine with the good box. I replaced the ac voltage regulator in the bad box and I also changed the exciter bridge rectifier assembly in the distribution box because I’ve heard those go bad as well. After all that it will not produce power at all anymore and I’m out of ideas. Any input is appreciated.

After further troubleshooting I’ve discovered that the issue is in the ac output box. I have replaced the a4 bridge rectifier board and still not getting any power.

 

[Guyfang]

Probably, the next step it to check the CT's. The current transformers. And I assume you have checked the box out good. Its a mouse hotel, and they often turn it into a flop house. CVT1 and CT1 could be bad, and you can test them. The below test procedure is in the -34 TM, page 6.15. You need a Multimeter to do the tests. You need to remove the wire from the items before testing.

7) Current Voltage Transformer (CVT1). Using an
ohmmeter check three primary windings of transformer
(figure 1-1, 6-7.1 and 6, figure 6-9) by measuring resistance
from terminals H1 to H2, H3 to H4, H5 to H6. Resistance
must be 2.27 ohms ± 0.227 ohms. Check resistance in three
secondary windings of transformer by checking from
terminals Xl to X2, Xl to X3, X2 to X3. Resistance
must be 1.68 ohms ± 0.168 ohms. Check resistance in
control windings by checking from terminals Cl to C2.
Resistance must be 9.6 ohms ± 0.96 ohms. If any of the
windings do not show the proper resistance, replace
transformer.

Current Transformer (CT1). On the current
transformer (figures 1-1, 6-7.1 and 7, figure 6-9) only the
secondary windings can be checked. Using an ohmmeter
check resistance in secondary windings by checking from
terminals 1A to 2A, lB to 2B, lC to 2C. Resistance must
be 0.5 ohms ± 0.05 ohms. If any of the windings do not
show the proper resistance, replace transformer.

 

[rickf]

I'm confused, You said you put another control box on and it was working fine. Then you said you changed a bunch of stuff and it no longer made power. I am guessing you went back to the old control box? But from the sounds of it you are now outside of the control box. So did the good box die or is something else now going on. Having trouble following this one. It still sounds like you are throwing new parts at it and then asking why they don't work.