Mep701a stopped producing power

Hello SS members, happy new year to everyone! I was wondering if anyone could give me some insight on the issue I'm having. I have an off grid cabin and we use an MEP701a for power while we're building the place and is hard wired into the cabin as well. The other night at dinner the lights had shut off(generator stopped making power) I went outside to see if any fuses popped. I checked the 2 on the front panel, then opened the panel and checked the 2 inside the box. All good. The generator was still running. I checked all the gauges, I noticed I wasn't making any Hertz. The generator has 1450 hrs, I've put 1000hrs on it my self in 3 years, no problems, filters and fluids changed like clock work. Any insight would be great, we're building a custom cabin upstate NY and are a few weekends away from completion but are dead in the water with no power. Thank you guys in advance and God Bless!

Your hertz meter dosnt work, because it needs AC voltage. So, did the circuit breaker trip? Or is it still in the up positions?

Do you have the TM's for this gen set? Have you read the troubleshooting diagram? Can you use a multimeter and schematics?

were you using the gen set for anything else then lights when it quit?

Yes the circuit breaker was still in the up position. I have the TM and I've read the troubleshooting diagram. Schematics and multimeters are no problem. 5-10 minutes before the lights went out my mother was using a electric Coleman grill and I was using a circle saw. When the power cut off I only had LED lights running. I would of tried the troubleshooting procedures but it was 8 o'clock at night and -10 outside. My cabin is 5hrs away , so I'm trying to get as much info together as possible.

I would upload the TM's on a lap top. take it with you.

Sometimes, the circuit breakers just needs to be reset. It trips, but the handle doesn't go down. If so, just push it down, (you should feel it kinda slip, and then click into place) and then back up. If that is not it, look at the schematic and find the F1 and F2 wires on the volt regulator. Should be the last two wires on the left side of the regulator. BUT do not trust my moth eaten brain. LOOK. Its marked on the regulator. Have someone start the set up, while you measure the DC voltage on terminals F1 and F2. Anything over 6 volts is good to light off the exciter. If you have good voltage, (and you can read up on how to do this in the manual) then you can use the TM to check the winding of the gen set, but if I were to bet on it, the volt regulator is 99.999999% the cause of no output voltage.

If you do NOT have DC voltage on F1 and F2, then you need to start at the Start switch and work towards the regulator. I am not at home right now, or would look at the TM's and tell you what places to check.

If it turns out to be the voltage regulator , is it hard to swap a new one in? Would a specialist be needed? Or is this something my brother in law with 15 plus years as a union electrician could handle?

Changing a volt reg is tooooooooooooooooooooooooooooooooooooo easy. 4 screws, and about 7-8 wires? Not something I would call hard. The gen set uses a "universal regulator" That means it is used in 3-5 different gen sets. The only thing you need to look at is the wire diagram to make sure the jumpers are in the right place on the TB, and then hook up the 7-8 wires. Finding one may present a problem, not sure. There are threads about using new state of the art regulators. If push comes to shove, read up on it and get smart. A good electrician who repairs this kind of stuff, should be easily able to repair one.

quick look at the big auction site revealed one for sale. 399.00
NSN 6110-00-764-7621
part # 13219E0813

There are at least 6 more NSN's. But the reason they are no longer in the system is because they failed at a higher rate. If you want those numbers, tell me, will look them up.

Is there an particular reason a voltage regulator would give out like that?

The T2 transformer and the Q-? Transistor were a weak point. I will not say that's what's wrong with yours, but our support unit that repaired the regulators often complained about how many of them they replaced. My theorie is that too many people idled the gen set to cool them down. Idling is bad for regulators. But unless someone tears it apart, you just can not say with 100% certinly what went wrong. Have you looked at it yet?

My generator does ALOT of idling, right now we're building the cabin so at most I run an air compressor and circular saw at the same time. I have not looked at the generator yet it is 5hrs/320 miles away at my cabin. I think I might go ahead and order the voltage regulator, if it turns out not to be that I will at least have an extra on standby. I found one for a mep-016b for $300. Also is the t2 transformer and Q2 resistor built into the voltage regulator ? Or do I have to order those separate?

Offgrid14 said:

My generator does ALOT of idling, right now we're building the cabin so at most I run an air compressor and circular saw at the same time. I have not looked at the generator yet it is 5hrs/320 miles away at my cabin. I think I might go ahead and order the voltage regulator, if it turns out not to be that I will at least have an extra on standby. I found one for a mep-016b for $300. Also is the t2 transformer and Q2 resistor built into the voltage regulator ? Or do I have to order those separate?

Click to expand...

Idling means running at less than the 'regular' 1800 RPM. NEVER do that on a generator. It may be 'loafing' because of no load, but it should still be turning at 'full' speed.

Offgrid14 said:

My generator does ALOT of idling, right now we're building the cabin so at most I run an air compressor and circular saw at the same time. I have not looked at the generator yet it is 5hrs/320 miles away at my cabin. I think I might go ahead and order the voltage regulator, if it turns out not to be that I will at least have an extra on standby. I found one for a mep-016b for $300. Also is the t2 transformer and Q2 resistor built into the voltage regulator ? Or do I have to order those separate?

Click to expand...

I second SCSG-G4's comment. NEVER idle a generator.

Yes T2 and the Q2 transistor are in the regulator. Not to worry. Just make sure the jumpers on the volt regulator are in the same place as on the old one. They are all color different, so its just too simple.

If you know someone who works on that kind of stuff, the test procedures are in the manual. I do not think it would be hard to fix, and then you have a spare, or sell it.

Did the generator lose it's excitation field? Might want to try "Flashing" the field before throwing parts at it.

Buddy of mine called me over the summer from his boat and asked why he might have lost output voltage from his generator. Had him flash the field with a 9V battery and got the generator back up and running! Just a thought..

That's always a good thought. But his gen set stopped making electricity, and kept running. Normally when a generator loses its excitation field, its been setting too long, or the generator has been dropped, or had some sort of a shock. But it cant hurt. If you want to try that, LOOK at the sticker on the top side of the regulator. PAY CLOSE ATTENTION to what it says, and follow the instructions TO THE LETTER. Its simple, but get the Positive and Negative right. The old regulators did not have this warning label. Lots of people ruined regulators because they got the procedure backwards. And the army pulled the procedures from the manuals because of that. Oh, if there is no warning sticker, positive side of your battery goes to pin 20, and the negative side goes to pin 21.

Thank you guys for all your help. I have ordered the VR, seems like I got a good deal at $135. I will try and flash the field before I swap it out just in case. I will post back next weekend after I work on the generator.

Good luck!

Could you guys tell me if I ordered the right glow plug please. I thought I read up on it enough to make the decision but when it came in the package says 12 volt and I know my generator is 24 volt. The glow plug has AC-19G ingraved into it and the part number on the bag is 333-0242

PAOZZ 2920-01-275-4311 PLUG, GLOW .........................
333-0242 (44940)
19G (70040)

You should have the right plug.

And if the NSN was on the bag also, then you could have looked that up in the TM. For that matter, the part number, 333-0242 is also listed in the TM.

Hello again men! I have successfully labeled all the wires and removed the old voltage regulator. My last question is how do I test for polarity?

Do the wires have numbers on them? If so, no need to mark the wires. Simply hook them up IAW the wire diagram. I assume you are talking about the warning in message 13? If so, the positive side goes to pin 20, and the negative side to pin 21. The regulator is a universal regulator, so you need to follow the instructions on the regulator as to where the jumpers get hooked up to, and then hook up your wires. I will be up for a few more hours if you have questions. I am 7 time zones with you, so if its too late, maybe someone else will jump in and help. This is not tricky. Just hook up the wires.

Voltage regulator hooked up and still nothing