MEP-002A & MEP-003A Generator A/C Volt Regulator Info.

[Guyfang]

Good morning.

I just found some old files on my laptop. One of the files dealt with the MEP-002A and MEP-003A, A/C Volt regulators. The message was from CECOM, so its 99.9999999999% trustworthy. It seems that the A/C volt regulator for the 400 hertz and the 60 hertz model are compatible. The message stated that the military had long ago made sure that both NSNs were compatible, but had NEVER changed the TM's. So I asked someone I know, and he told me "its the truth." He should know. I was under the belief that as both A/C volt regulators had different NSNs, they were not compatible. Well, I is wrong. So there you are. If someone should have a regulator with the 400 hertz NSN, use it!

The really interesting thing here, is that in the 003A parts manual, there is a number for both the 400 hertz and 60 hertz A/C regulator.
NSN: 6115-01-037-9650, part number 72-5020, for the 60 hertz regulator.
NSN: 6115-01-095-7440, part number 72-5338, for the 400 hertz regulator.

In the 002A parts manual, there is only one NSN in the parts breakout: 6115-01-095-7440, part number 72-5338. That the same NSN listed for the 400 hertz in the 003A TM. AND, no listing what so ever for NSN or part number in the rear of the TM. Its as none of it ever existed. Strange, strange.


The next bit of info I do remember seeing, but so long ago, I was doing 150 KW Turbine gen sets, and didnt have time for "Small stuff". So I promptly forgot it. And this is something would check if I had a MEP-002A or MEP-003A.
View attachment Starter BurnoutDED.pdf

Hope this is of interest to someone.

 

[Triple Jim]

The 72-5020 and 72-5338 are the same for all practical purposes. There are minor and insignificant differences in the ratings of a couple components, but the circuit is the same. When I designed the replacement regulator that I sell, I went though every component, looking up its NSN and getting is specifications, so I'm not guessing here. The 72-5020 and 72-5338 boards are configured for 60 Hz or 400 Hz by using jumpers on the terminal strip.

The page you posted that tells how to prevent starter burnout is very interesting! I've wondered for a long time why some 002A and 003A wiring diagrams show the starter circuit wired so field flashing will not work after the generator is up to speed, and some show it the way we expect, so flashing can be done any time. This explains the change, which must have been officially done at some point along the way. And it means that any generator that's wired to avoid burning out the starter if CR2 fails is wired so that you can flash the field after the engine is up to speed.

My 003A is wired the "bad" way, so I think I'll make the change suggested.

 

[glcaines]

This is very good information. Thanks for posting!

 

[dangier]

Checked my 002/003's and they are all wired the "bad" way. Guess I have some work to do..
Many thanks for the info.

 

[Kahles56]

Guyfang,

Thank you for the starter information,

By chance do you have any more "tid" bits of information like this hidden away that you could provide .

Also is there a repository of these corrective measures that you know of that can be searched for info like this.

 

[Chainbreaker]

Regarding: "Prevent Starter Burnout" wiring advisory supplied by Guyfang...

I checked 2 of my MEP-002's and a spare control box and here is what I found:

1991 Genset & 1991 Spare Control Box both had the revision already incorporated "good way"

1986 Genset was wired the "bad way" with wire P59E16 wired to TB4-3 (right side terminal), The wire was just long enough to move down to TB4-12 (left side terminal)

If you have difficulty identifying P59E16, if it is wired "good way" you should only have only 2 wires on TB4-3 and a total of 9 wires total between TB4-12,13,14 Left+Right.

Both my 1991 Control Boxes had P59E16 located on TB4-14 Right because they must have issued an ECO revision to wire it that way at some point.

Photos (top half) & (bottom half) of TB4 in 1991 Control Box showing TB4 with OEM wire harness wired correctly:



Photo of 1986 with P59E16 after I relocated to TB4-12 Left; placed under existing wire:



TIP: The schematics on top of my genset Control Boxes did reflect the way P59E16 was actually connected. If you look at the lower right most portion of schematic you will see "K3" round schematic symbol just above the S8 switch connection table. If you look to the right of the X2 terminal on K3 you will see "TB4-3". If the wire on schematic (P59E16) just below that coming out of J2-J runs straight across to the right edge of schematic and then turns up to TB4-12,13,14 your unit is "most likely" wired "Good Way". If your schematic shows P59E16 going from J2-J and going up to TB4-3 is "most likely" wired "Bad Way" unless someone along the way performed the mod. Regardless, I would verify wiring inside control box.

"Bad Way" schematic photo:



"Good Way" schematic photo:

 

[Guyfang]

Never trust the schematic on the gen set. They are often wrong. Its a good guide, but if you can, use a TM schematic. The schematic in the TM's is mostly right, but it's important to always have the latest version of manual and the latest change posted to that manual. A good case in point. I spent an hour on the phone with a soldier who was using a (very) outdated manual. Every time I told him to look at this page or paragraf, it was like we were speaking two different languages. After a while, I asked him what the TM date was, and then it all became clear.

Great post Chainbreaker. Pictures are worth a million words.

 

[Triple Jim]

Every time I told him to look at this page or paragraf...

Once in a while I can tell you've been in Deutschland for quite a long time.

 

[Light in the Dark]

Can't wait to get some time this weekend to take a look at mine. Thanks for the info!

 

[Guyfang]

Sometimes it feels like wayyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy to long. But the beer is good!

 

[dangier]

Got all my 002s and 003's corrected. Was a snap once I figured out where P59E16 connected to (thanks to Chainbreaker)! My TB4-3 (Right) P59E16 was buried under other wires on the first unit. Many thanks to Guyfang for raising the issue and Chainbreaker for the pictures. Hope I get the chance to return the favor!!!
David

 

[Guyfang]

Guyfang,

Thank you for the starter information,

By chance do you have any more "tid" bits of information like this hidden away that you could provide .

Also is there a repository of these corrective measures that you know of that can be searched for info like this.

I am still looking to see what I can find. Never know!

You can also look in back issues of PS magazine. Its VERY time consuming, BUT, you can learn a lot of great stuff. I personally, read EVERY copy of PS Mag when we got them every month, at least twice. Sometimes more often. Its simply a great publication.

 

[dangier]

I pulled a couple of years as a Army vehicle dispatcher in the late 70's and looked forward to the PS magazines (although they were always 6 or so months late). Guess everyone else read them first......

Looks like a searchable website is available here:

http://dig.library.vcu.edu/cdm/landingpage/collection/psm


David

 

[Guyfang]

Thanks David. There is indeed a wealth of info in PS.

 

[Triple Jim]

Actually, I wish we could simplify English a little. Remember ghoti, which is pronounced "fish"?

(gh from enough, o from women, and ti from nation)

 

[glcaines]

I checked out my MEP003A, manufactured 07/92. It was wired the correct way. Thanks everyone for the information.

 

[Keith_J]

Now yet another thing to check. I have a 002a and maintain another 002a w ASK and a 003a.

I grew up with these when I was in Uncle Sam's Army. Somehow didn't see that issue of PS.

 

[Guyfang]

The problem with such changes is this. Money. Not that it cost anything to make the change. No parts involved, just a few minutes time. The money comes in with TM changes. And think about thousands of gen sets, with the schematics on the metal plates riveted to each and every set. When this change came out, TROSCOM, (Troop Support Command) the forerunner of CECOM, (Communication Command the people now responsible for power generation) didn't change anything. It simply cost too much, to make one little change. So everyone waited until there is several changes, or several mega changes. And that can take years. When enough time goes by, people forget little things. Sometimes the Commands send out teams to make such changes, and they also change the data plates. But some sets always fall through the cracks. And I have to admit, the 70's were a bad time. We had very little funds, so lots of stuff fell through the cracks. That's one reason you need to always have the latest TM, with the latest changes. When we got a new change, I always read the change before putting it in my TM's. Just inserting the change is not enough. You have to KNOW what it is also.

 

[GREENMV]

Just another thing to remember.... Thanks Guy