Wet Weather Issue With MEP 831A

[Lostranger]

I am brand new to this forum. I bought an MEP 831A about a month ago. Less than 30 hours showing. Solved the battery issue with a stacked pair of garden tractor batteries and fixed a couple of minor wiring issues.

This machine works great when the weather is dry. When it's wet—even misty—it runs three seconds and then shuts down. The Overload Short Circuit light comes on when it dies. The GFCI usually has to be reset when I start the thing even in dry weather, but I've taken the GFCI and the 110v outlet out of the circuit, and the machine still dies after 3 seconds.

I need to get this thing running in the wet. I have basic circuit reading skills, but I don't even know where to start troubleshooting this issue. Any help would be greatly appreciated.

Jim in NC

 

[Guyfang]

Jim,

Take off the top covers, open all the doors, and open the control panel door. Then, at night, with no lights on, start it up. Have several people standing around looking at the set from different angles. Do you see a spark anyplace durring start up?

Don't laugh, I have used this trick many times, and sometimes it works real well.

If not, try this. Follow all the steps above, and hold the S-1 (start switch) up, keep it up, do not let it go, let the set run 30-40 seconds if it can, then snap up the S-7, (battle short switch) and then let the S-1 go. Will the set still run? If so, perhaps your K-8 relay (short circuit relay) is bad? Move the K-8 to one of the other relay sockets and see if you still have problems, but in a different area. Proof that the K-8 is bad. This sounds like you have a bad relay, or a wire worn through, someplace on the set. I would start looking in the control cube. You might also have something small laying in the control cube that is ALMOST touching a wire or TB, (terminal board) connection.

 

[Lostranger]

Jim,
Don't laugh, I have used this trick many times, and sometimes it works real well.

Hey Guyfang,

Not only am I not laughing, I am deeply grateful. That is exactly the kind of info I was hoping to find here. I'll be working on that as soon as I get home.

All the best,

Jim

 

[Guyfang]

We willknock this out Jim.

Take care and will shout at you later. Need to hit the hay. Its almost 23:00

Guy

 

[Lostranger]

I have a replacement relay being shipped. One of the three behind the control panel (the right one) appeared to have an internal arc when I checked the machine in the dark. I've not had time to swap relays and see if that makes a difference. The replacement should be here Monday or Tuesday. I'll have more to say after that.

Jim in NC

 

[tburk49760]

Can we assume this issue is with no load connected? Had similar issues and it was a wiring issue in my extension cord.

 

[Lostranger]

No load. This problem is in the generator.

Thanks.

 

[Dewie38]

The K8 relay is in the inverter, the relay all the way to the right in the control box is an AC relay (K15) the other 2 in the control box are DC, don't swap them, if you put one of the DC relays in the AC relay socket the relay will fry.
If the set shuts down then the fault is a short circuit, overload only opens the contactor.
And the issue is probably the inverter.

 

[Lostranger]

Thanks, Dewie38. Now I'm more confused than ever. Hopefully the relay I have coming is the AC relay. Would that relay have a constant light inside that I might have mistaken for an arc?

Jim

 

[Dewie38]

yes all the relays in the control box have LED's so you can tell when they are energized.
Check all the relays and make sure the ones to the left are DC. and the one to the extreme right is an AC relay
Sounds to me like you have a bad inverter and if you flip on the Battle Short switch it will still shut down on short circuit.
Battle Short bypasses all faults except short circuit.

 

[Lostranger]

It does still shut down on Battle Short.

 

[Lostranger]

Can the inverter be repaired?

 

[Guyfang]

For the army, it was a DX, (direct exchange) item. That meaning, pluck and chuck. Remove, turn in, get another good one, (you hope) and replace. Thats why the parts manual will not show you what parts are in the inverter.

 

[Lostranger]

The fellow I bought the gen set from sent me a different inverter, and I finally got it installed yesterday. Generator did fine then, but it was dry. We had rain overnight, and now I'm having trouble again. I no longer have the "run a few seconds and stop" syndrome, but it's not making usable power. Seems to run too slowly, and when I attach a load (circular saw) i get mixed results. Sometimes it will run the saw for a second or two then the short circuit/overload light comes on. Sometimes nothing happens. Sometimes the generator shuts down.

On the subject of shutting down, sometimes I can't get it to do so. Sometimes neither the main switch nor the emergency stop will get it to cut off. Eventually, playing with those two switches will shut it down, but I've not found a consistent pattern.

Any ideas on these issues? Does anyone know of a troubleshooting manual for this unit? I need to get it working.

TIA,

Jim

 

[Guyfang]

I just up loaded the manuals in the TM upload section.

 

[DieselAddict]

I've been wondering if the internal circuit boards of the inverter were comformal coated. If so the coating could be breaking down allowing moisture to cause the problems.

It may be worth taking apart one of the inverters an inspecting the circuit boards. If you find damaged coating it can be stripped off and reapplied.

 

[Lostranger]

Thanks for the uploaded manual. I'm reading it now. Wish I had had this from the beginning.

Jim

 

[Guyfang]

Ask, and you shall receive.

 

[Dan91d]

Do anyone by chance have the nin for the AC relay the TM 9-6115-639-13&p only list the DC relays. I may have a DC relay in the k15 area led lights up green I notice on a working gensets k15 is red led. I have 3 mep 831 with the problem contact switch won't close no voltages out the lugs but get 120 AC out of the gfci . I'm trying my best to avoid ordering the inverter box
Thanks

 

[DieselAddict]

If you have power at the GFCI then the inverter is making power.

Have you done the troubleshooting to see why you are not getting power to the output contactor coil?

Have you tested the output contactor to make sure it works if you apply power to the coil?