MEP-804A OVERVOLTAGE where do I start?

FLCracker

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Daddy said go to trade school not college...I should have listened to him.

I have a MEP-804A with a manufacture date of 5/95. This weekend I went to do the monthly test run and got a "OVERVOLTAGE" light and the generator immediately shut down. I have been searching the OP, Maintenance and TM manuals for trouble shooting help but did not see anything specific as to what to do when I get this OVERVOLTAGE error. I would appreciate a point in the right direction.

Here is a bit of history:
Immediately after I purchased it I noticed the batteries would not hold a charge between monthly test runs. I installed a marine type battery on/off switch, dead battery problem solved.

About 6 months ago the Frequency gauge would peg out over 62 Hz and there was no change when adjusting the potentiomiter. If I shutdown and disconnected/reconnected the battery, start, shut down, repeat multiple times (6-10 times) . It would run just fine at 60 Hz.

Yesterday, Dec 5, I am getting the "OVERVOLTAGE" error.

Yes, I should have started problem solving when noticed the Freq issues, but did not want to have the gen down during hurricane season...so now its down.

I have looked through many of the post, but I really have no idea where to start. I have a multimeter and a very basic understanding of generators. I admit this generator is more than I need, and more complex than I would like. Any suggestions to get me started would by very much appriceated.

Thanks
 

Guyfang

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Important!! Do you have the Quad Circuit MWO? Modification Work Order. The Volt Regulator, (A1) is a known problem area. So, if you have the MWO, then start the set. Watch the volt meter. Will it come up to about its normal reading, and then the set shuts down for overvolt? Or not?
 

FLCracker

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Location
Central Florida
GuyFang, THANKS for the reply. I am not sure how to answer about the Quad circuit MWO. I searched TM 9-6115-643-24P but found no reference for that. Please let me know if I should be using a different TM. I am including a photo of my voltage regulator if that helps to answer your question.

I did start the unit and watched the voltage meter. The volts jumped up to about 240 and then down to 220 . The overvotage light came on almost immediately as far as I could tell trying to watch both at the same time. As soon as I let off of the Start switch to return to "Prime & run" it shut down.

Thanks for your help.
 

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mciikurzroot

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My offering ? open the control panel and to your lower left below the annunactor panel is the white Molex nylon type connector, find the holding tab and press and remove the connector at the same time. your set should start and run as normal, [hopefully] now i said normal, thats a bit loose. but what should happen is your meters should all read like oil water volts and freq. Now keep in mind you're naked here, with no protection, [emm this has a bad direction heading] be sure you can tell your normal speed sound from one making really higher speed 2000 plus rpm .. but lets presume your reading are normal for the sake of this test. things you WONT be able to do is transfer the load, in this test that function will not work. but you dont care , you're trying to find a cause for shutdown. If the meters and speed sound ok, you're pretty good shape. But next is to pull off the lid covering the whole control box, then go through and loosen ONE by ONE every screw , every single one on damn near everything, skip the battery shunt, its not ur problem, but most often by loosening the wires and terminal lugs and resetting them every one, when you're done somewhere in the process you have solved your shutdown situation, it about 275 -300 screws to check loosen and then retighten, and the madness is you will never likely find the offending one/s but your false shutdowns will be solved. its maddening effort no getting around it.. but resistence builds up and slight corression does not help and the worst is if some dip stick has put on that gel or conductive grease, and terminals and lugs are turnning green, then it just does not end... do not keep your handgun even anywhere in sight.. but a cold beer and good attitude will go a long way.. Now this effort is only if your set in this initial test is normal, not over speeding or wild voltages, make you voltage readings on the volt regulator reset those screws and lugs first. But a 25 year old set will exhibit false shutdown/s conditions from infrequent or seldom use, along the way rotate all you front panel pots and rotary switches briskly and a good number of times, get some pot cleaner and spray the speed and volt pots or even replace them if they have dead spots .. if your set is an original 95 and no TIER reset then the VR mod Guyfang mentions will not have been performed .. that's the cheepest insurance you can do or buy to protect that system . if your speed pot is erratic try and clean it, if true speed is erratic and you feel comfortable the speed pots is good, using you VOM to follow the resistance swing of the pot, then cycle the 4 pot adjustments within and along the top of the Barber governor control box, its blue and along the top row just right of the centerline control cabinet back wall, but this is not for the faint hearted, but most likely the cause of erratic speed conditions if it gets to this item after performing all the other test... but by now you will be king shit of learning and testing your set so you can set it back up per the TM and be very proud of yourself ...
disclaimer: several others on here will give you this advice in smaller logical steps , try all those suggestions first.
best: mac/mc
 

FLCracker

New member
7
1
3
Location
Central Florida
My offering ? open the control panel and to your lower left below the annunactor panel is the white Molex nylon type connector, find the holding tab and press and remove the connector at the same time. your set should start and run as normal, [hopefully] now i said normal, thats a bit loose. but what should happen is your meters should all read like oil water volts and freq. Now keep in mind you're naked here, with no protection, [emm this has a bad direction heading] be sure you can tell your normal speed sound from one making really higher speed 2000 plus rpm .. but lets presume your reading are normal for the sake of this test. things you WONT be able to do is transfer the load, in this test that function will not work. but you dont care , you're trying to find a cause for shutdown. If the meters and speed sound ok, you're pretty good shape. But next is to pull off the lid covering the whole control box, then go through and loosen ONE by ONE every screw , every single one on damn near everything, skip the battery shunt, its not ur problem, but most often by loosening the wires and terminal lugs and resetting them every one, when you're done somewhere in the process you have solved your shutdown situation, it about 275 -300 screws to check loosen and then retighten, and the madness is you will never likely find the offending one/s but your false shutdowns will be solved. its maddening effort no getting around it.. but resistence builds up and slight corression does not help and the worst is if some dip stick has put on that gel or conductive grease, and terminals and lugs are turnning green, then it just does not end... do not keep your handgun even anywhere in sight.. but a cold beer and good attitude will go a long way.. Now this effort is only if your set in this initial test is normal, not over speeding or wild voltages, make you voltage readings on the volt regulator reset those screws and lugs first. But a 25 year old set will exhibit false shutdown/s conditions from infrequent or seldom use, along the way rotate all you front panel pots and rotary switches briskly and a good number of times, get some pot cleaner and spray the speed and volt pots or even replace them if they have dead spots .. if your set is an original 95 and no TIER reset then the VR mod Guyfang mentions will not have been performed .. that's the cheepest insurance you can do or buy to protect that system . if your speed pot is erratic try and clean it, if true speed is erratic and you feel comfortable the speed pots is good, using you VOM to follow the resistance swing of the pot, then cycle the 4 pot adjustments within and along the top of the Barber governor control box, its blue and along the top row just right of the centerline control cabinet back wall, but this is not for the faint hearted, but most likely the cause of erratic speed conditions if it gets to this item after performing all the other test... but by now you will be king shit of learning and testing your set so you can set it back up per the TM and be very proud of yourself ...
disclaimer: several others on here will give you this advice in smaller logical steps , try all those suggestions first.
best: mac/mc
OK, so pack a lunch right? I may have to wait for the weekend to start this.
 

mciikurzroot

Active member
Supporting Vendor
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Location
wimberley texas
Yah i sorta went too far,, like some times you ask a person what time it is, and you end up building a watch... but break it into bits and you will solve your issues or at least determine what is wrong. And again, if your set is a 95 build and no Tier reset, you wont have the A1 fuz mod, but your luck is good, this is the simplest easiest mod of all time to perform... its simple enuff i can do it...
best: mac/mc
 

Guyfang

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Location
Burgkunstadt, Germany
Here is a picture as requested. No such fuse as per picture by kloppk. Does this mean my unit does not have the quad circuit MWO? Next step?
Yes, you do not have the MWO. Like Mac said, its easy to do. But you should do it before starting the set again. Your A1, (AC volt regulator may be bad, and causing the gen set to over-volt. This can lead to main generator failure. So put in a fuse, and then we can go from there. The attachment I set, has part numbers and all that you need to do the MWO.
 

Arty

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Location
Los Angeles
Hi. What was the final resolution to this? I have a 2010 built MEP-804B with the MWO. I get overvoltage light instantly and it shuts off. Is it for sure A1 or should I also be looking elsewhere before ordering a replacement? Any steps for determining if A1 is bad?
 
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