MEP-003 Rectifier Board Burn

[Guyfang]

The S-1 start switch would be my first guess. If it is "stuck" in the excite position, it would continue to send voltage to the A-4. In any case, you need to look at your wiring in the control box. Can you see any place someone has moved things? or cut wire ties?

 

[GREENMV]

@Guyfang I was Busy yesterday and today Is raining cat's and dog's so I will probably get to It tomorrow. I will replace the S-1 and double check the VR wires & Others. I do see one wire someone messed with that I am going to check. Thanks

 

[jamawieb]

There are 2 diodes in the A1 assembly, which is located in the control box, where the gauges are located (upper right corner). These 2 diodes, control the current to the rectifier board. If they fail, current will continue to back feed to the board and burn the resistor. It took me 3 weeks to figure it out. The diodes are between A1-5 and A1-6 ; then A1-7 and A1-8. If you take those wires off and test between them you can check the diodes without taking the panel completely out. The diodes are tucked behind where you can't see them. Also this will cause the starter lockout not to function and your starter will stay engaged without ever letting go, burning the starter up.

 

[GREENMV]

@jamawieb I will be working on the Gen tomorrow. I printed your suggestion and will check on that. Thanks

 

[Guyfang]

Thats good info Jamawieb!

 

[GREENMV]

To Guyfang, Triple Jim, Jamawieb. Update: I Won. I replaced the A1 and S1 plus checked the wire's to A1, S1, Rectifier Board, Voltage Regulator. The wiring was right. The Control panel Is now working again and did not fry my Resistor on the Bridge Rectifier Board. "Thank God" It had to be the S1 or A1. Thanks to you guys for the help.

 

[jamawieb]

Great news! Check the diodes on A1 if you have a multi-meter. Really easy since you have it out, you can just test them with the leads on each side.

 

[GREENMV]

@jamawieb, I will and I would have never found that by the way. Question for you that you might have an answer. Can I use a 5Kw AC box on a 10 Kw by just replacing the Breaker?

 

[jamawieb]

@jamawieb, I will and I would have never found that by the way. Question for you that you might have an answer. Can I use a 5Kw AC box on a 10 Kw by just replacing the Breaker?

Yes but the breakers are the same on the 5kw and 10kw, they are both 100amp so you don't change those. The thing you have to change is the windings that go through CVT1 transformer. CVT1 is mounted on the bottom of the box and has the large wires running through them. There are 2 sets of wires that are wrapped through each hole and the 5kw are wrapped twice as many times as the 10kw. So what you have to do is take some windings out of the 5kw to be used on the 10kw. It's a PITA to pull the wires out, reducing the number of times they are wrapped so be ready to take 2 hours to do it for the 1st time.

 

[Guyfang]

I want to add to this. I mentioned in another thread, that there is TWO stock numbers for the 100 amp breaker in the 003 parts TM. I have been snooping around, and now I know why. And perhaps this truly has something to do with some people being able to drop a "shock load" on the MEP-003A, and sometimes it pops the CB, and sometimes not.

In the 5 KW parts manual, the NSN for the breaker is: 5925-01-050-0484, (no UOC). The NSN's for the CB in the 10 KW parts manual are, 5925-01-050-0484, (same as the 5 KW, but with a UOC, of A&C) and the second number is: 5925-01-097-4925, (UOC B). I looked up the UOC, (Usable On Code), and it tells me that only certain serial numbers get the CB 5925-01-097-4925. But not WHY they do. So I went back to basics. Looked at the 5 and 10 KW parts manuals again, but this time followed my own rule #1. Look at the cover. Look at the explanation of the UOC's. And then it became clear.

There is only one model 5 KW gen set, Model MEP-002A. A 60 hertz machine. Then looked at the 10 KW book, and saw that it was listed as two different machines. MEP-003A and MEP-112A. I have known this for 40 years. But assumed, (something that always gets me in trouble), that the 5 KW also had TWO models. Why I assumed this, I just don't know, but I guess after looking at this TM 10 billion times in the last 40 years, I was looking, but not SEEING. Then I looked at parts. The UOC, B coded 10 KW machine had no 110 volt outlet. its 400 hertz.

The NSN for the RIGHT CB, for both the 5 &10 KW is 5925-01-050-0484. Its for a 60 hertz machine. The NSN 5925-01-097-4925, is ONLY for 400 hertz machines.

Over the last million years, lots of people have scrapped the 400 hertz machines, and used parts to fix their 60 hertz machines. And lots of people who look at a parts TM, may sometime not LOOK at the UOC, and order the 400 hertz CB. Sadly, the FEDLOG doesn't give a technical breakdown of the CB's characteristics. Perhaps the 400 hertz CB pops earlier? Perhaps the 60 hertz CB pops earlier? I don't know. What I do know is that it might not hurt to look at the NSN or better yet the part numbers on the CB's to see if this could be a reason why some pop when they do not exceed the rated current.

5925-01-050-0484
Part number: 72-5173 or CD3-Z142-1


5925-01-097-4925
Part number: 72-5174 or CD3-Z75-5

 

[GREENMV]

What happen to the old pages? I liked the other. I am going to remove the breaker that Is tripping to see If there's any part #'s on It. I will update when I do.

 

[Guyfang]

I went to the manufactures web site, and snooped around. Indeed, had I looked there first, the light in my head would have come on sooner. The part numbers showed up in their inventory, and it says, in reaaaaaaaaaaaaaaaaal small print, 50-60 hertz and 400 hertz, for the two different CB's.

 

[GREENMV]

@Guyfang, I assumed It might be 400Hz. That word also gets me into a lot of trouble. I posted In the breaker thread. @Guyfang, The other Breaker CD3-Z75-5 is a 6 Post/Lug. The 60Hz breaker has 12 I believe. I think this is the other difference.

 

[Guyfang]

OK, lets see what's on the side of the CB.

Yeah, the word assumed, brought all the demons from **** down on my head while in WOC. Its a word I rarely use anymore.

You know, back in the 90's, I used to go to DRMO and pick up 4-6 AC output boxes, and tear them apart, redo them for 5 and 10 KWs, and keep them squirreled away for a rainy day. When I would send my guys out on a trouble call, for a 5 or 10 KW, they always took one of both types. Saved the day many times. And, it gave my guys a good way to get smart on repairs and troubleshooting when they reworked the boxes. I don't ever remember looking at CB's to see if I had the right one, and if I didnt, my guys didnt. I just wonder.................................................

 

[GREENMV]

I want to Thank jamawieb for His wisdom, The Idiot award for today go's to Ding, Ding, Ding "MYSELF" I got myself into trouble again assuming my 10Kw Gen was complete with only 40 hours on It and had the correct 10Kw AC box. I got to thinking about what jamawieb said about the CVT1's being different on the 5Kw and the !0Kw so this morning I checked my 10Kw to see the wraps on the CVT1 and It was staring right at me, I had a 5Kw AC box on a 10Kw Gen. No wonder my breaker was tripping. Now I have a brand new breaker for a paper weight. It just go's into Parts Stock?

 

[jamawieb]

I'm glad you figured it out. Now all you have to do is take half the number of wires that wrap around CVT1 out and zip tie them to the side; you'll have your 10kw distribution box.

 

[jamawieb]

It's good to have a backup breaker anyway. They are actually filled with a fluid from my understanding and after extended amounts of time of exposure to the elements, it dissolves. When the fluid dissipates, it causes the breaker to trip prematurely.

 

[GREENMV]

It's all Good, I've had dinner and stopped kicking my self. I had another 10Kw AC box, Just swapped them out. Now I have a spare 5Kw box for the future Gen Build If needed? I will learn from this mistake. Now I have a nice 5Kw Gen that needs some loving.

 

[Guyfang]

That's what this forum is REALLY about. Yeah, fixing stuff, that important. But when we all learn something from someone's experience, that's what its all about.

I loved it, when we were fixing "things", with one of the Newbies, and they "got" something. The lights came on in their eyes, and the finally UNDERSTOOD! Makes it worth all the work, when it happens.

My Mentor, from the early days in the army, who by the way lives not far from here, laughed till he cried, when my first home built full wave rectifier burned up. Because when it burst into flame, (I had no fuse to protect it) and caught the table on fire, I knew right then, what I had done wrong. Stupid mistake. I never forgot it.

 

[screejunk]

There are 2 diodes in the A1 assembly, which is located in the control box, where the gauges are located (upper right corner). These 2 diodes, control the current to the rectifier board. If they fail, current will continue to back feed to the board and burn the resistor. It took me 3 weeks to figure it out. The diodes are between A1-5 and A1-6 ; then A1-7 and A1-8. If you take those wires off and test between them you can check the diodes without taking the panel completely out. The diodes are tucked behind where you can't see them. Also this will cause the starter lockout not to function and your starter will stay engaged without ever letting go, burning the starter up.

Hello, we have a similar issue with rectifier board burning up, including a new one We have installed a new master switch and we have checked the diodes. Our tech, who is amazing, is still scratching his head... Is anyone aware of other points of failure to check to prevent the rectifier board from burning up? Any help is much appreciated. THANKS