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10 kw generator mep 803a

leedawg

Member
270
10
18
Location
Napa / CA
Well, you just eliminated about a third of that circuit as being the problem. At this point leave CR5 alone since it isn't causing the "pop" of the breaker.

What you might do next is to swap the K12 relay with the one next to it (to the right not left) just to make sure that the relay itself isn't bad somehow. The relay to swap with is the one to the right of K12, NOT the one to the left. The one on the left is the starter/field flash switch and that is unique - there is only one of them in the unit.

The other five relays are identical.

The "stuff" in the back of the unit in your picture consists of the AC contactor which is the square thing that has the heavy wires on it and the voltage selection switch. That diode is not CR5. None of that "stuff" back there will be your problem -- it is all best left alone at this point since it is the high voltage section and it isn't going to work until the "pop" problem is solved.

I'm out of town right now; about 200 miles away from the schematic that I use, so I can come up with another idea or two on Monday....

z
So this has been a great thread to follow and since we were already talking about relays my 803a is missing the relay at the far left as you can see in the pictures I posted. Would one of you that does have this relay i believe it is S14 be so kind as to take a close up photo of the writing that is on it so that I can source one for my unit. As I understand it is different from the rest of the ones there and it is responsible for the starter and field flash. I would very much appreciate it Thank you.

Oh and to the OP what ever happened with your CB1 breaker popping out did you track down what the problem was or did you just give up in July and have not been working on it since then?

20141005_170428.jpg20141005_170420.jpg
 

zarathustra

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The "relay" on the far left is actually an electronic switch. I've got one sitting on my desk right now. I have never seen one of these available for sale.

This switch samples the RPM's of the engine from the sensor just below the starter, and when they hit 600 (or 800?? - don't remember which off hand), the starter shuts off and the field flash circuits are energized - that is the ONLY thing that this switch does - switch the starter off and turn on the field flash. It has a circuit board inside with around 20 components on it. One 8 pin chip, one field effect transistor, 3 diodes, one zener diode, 10 resistors, and 5 capacitors. All this is stowed in a case like the other relays.

The best part about this switch is that it isn't really necessary at all if one modified the electronics just a little.

If you are reasonably clever with electronics you could eliminate this part altogether by adding an additional momentary contact switch. That is what they did in the MEP831a generator. The mep-831a has a start switch that starts the unit. When the unit starts you let go of the switch as usual. At that point the unit is running but making NO electricity.

Then he would depress the momentary contact switch for 1 -2 seconds to flash the field and then release -- and the generator is making electricity.

I haven't laid that modification out in terms of exactly what pin on the switch goes where, but it wouldn't take more than a few minutes to figure it out. Just think in terms of making it like the 831a unit.

The only parts you would need to do this mod is another relay base -- you could take a relay like the other ones in the unit (easy to get - I've got 50 of 'em), open it up and strip out all the internal guts so that all you have left is the black base.

Some wire to make the normally closed connections on the relay base.
A momentary contact push button switch. (or a momentary contact toggle switch with a guard like the battle short switch might be better so that the switch doesn't get accidentally energized when the unit is already generating electricity)
Wire and crimp on connectors to patch from the relay socket ( the gray socket that the relay base would plug into) to the push button switch.

I haven't done the modification myself, but if I needed to (and right now I'm three switches short of need) I wouldn't hesitate to do it.

By the way, this switch is electronic, so it won't be clicking or making any noise at all.

z
 
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zarathustra

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Location
glasgow,ky
Since you got me thinking about these monsters again I just noodled around and found out where to get a new one..

If you want to buy one here is a source:

Quantum Controls
Chanhassen , MN
1-952-361-3694
Ask for Wendy
Price is 75 dollars each

They have them in stock right now which is a little unusual since many military vendors don't stock spare parts -- they just manufacture to fill an existing order.

You don't get a price break until you order more than 50.


z
 

leedawg

Member
270
10
18
Location
Napa / CA
Since you got me thinking about these monsters again I just noodled around and found out where to get a new one..

If you want to buy one here is a source:

Quantum Controls
Chanhassen , MN
1-952-361-3694
Ask for Wendy
Price is 75 dollars each

They have them in stock right now which is a little unusual since many military vendors don't stock spare parts -- they just manufacture to fill an existing order.

You don't get a price break until you order more than 50.


z
Thank you so much for the detailed response. I had no idea that was not another relay to be honest before I read this thread I was just going to order another one of the relays like the other five for bout 20 bucks and pop it in there. Sounds as though it is a pretty specialized switch to just do what the older units did with a mechanical switch that would lock you out from re-engaging the starter into the fly wheel gear when the motor was running. I like your idea of just wiring up a the starter switch straight to the starting terminals and just put another NO push button or something to flash the field after the generator is up online to flash it. However since you did find the part to replace it with I am going to give Wendy a call and probably just order one to keep the unit original. Its just been sitting in my back yard for the last 8 months have not really had time to start working on it hopefully not more is wrong with it. Thank again though for the reply.

Lee
 

TurboJoe

New member
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2
0
Location
Lafayette, NJ
The military makes the whole set very complicated in an effort to "keep it simple". In the commercial realm almost all of those relays and wiring are replaced with one digital generator controller and 3-4 standard double pole relays. I am in the process of doing just that to a mep802 I have that apparently caught fire at one point in its life. Work has been busy so I havn't had much time to work on it recently, but I will start a build and document thread shortly.
 

leedawg

Member
270
10
18
Location
Napa / CA
So just as an update.

I called quantum controls and ordered up one of the switches. The part number is as follows.

S14 switch in the mep-803a, part # SDS1008821091 switch. Thanks again for all the help now gotta wait for it to come and then onto the next problem.

Lee
 

bullwhacker

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Location
san jose calif
If you are referring to me?
I've been gone due to work and just was able to look again at this thread. I haven't been able to run the meter tests yet and will up date in about three to four weeks when I get back state side.

So this has been a great thread to follow and since we were already talking about relays my 803a is missing the relay at the far left as you can see in the pictures I posted. Would one of you that does have this relay i believe it is S14 be so kind as to take a close up photo of the writing that is on it so that I can source one for my unit. As I understand it is different from the rest of the ones there and it is responsible for the starter and field flash. I would very much appreciate it Thank you.

Oh and to the OP what ever happened with your CB1 breaker popping out did you track down what the problem was or did you just give up in July and have not been working on it since then?

View attachment 520424View attachment 520425
 

leedawg

Member
270
10
18
Location
Napa / CA
Thanks for the reply will look forward to reading your update when you get back stateside. I have since tracked down the relay with some help from some others on the board. I will post up some close ups so you guys can see it. I have not progressed any further on the machine itself though have been pretty busy last few months.
 

leedawg

Member
270
10
18
Location
Napa / CA
So an update as promised I did indeed obtain the special switch thanks to
zarathustra and his great lead on this part.

So I did contact

Quantum Controls

Chanhassen , MN
1-952-361-3694
and asked for Wendy

The part number for
S14 switch in the mep-803a is part # SDS1008821091 switch.

Here are some photos of the relay and what it looks like in case anybody needs to know.

SO did indeed pay the 75 dollars pretty cheap considering how easy it was to get the part in my opinion.


 

Attachments

Guyfang

Moderator
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Burgkunstadt, Germany
Just wanted to add here, that the set WILL start with a relay plugged into the S-14 socket. Found that out one dark and cold/wet night when I had to drive 102 klicks to Graf, Germany. Flashlight in my teeth, standing on a stack of german beer cases. Which is how the relay got stuck in the wrong socket in the first place. Beer and pitch black night. NG unit. Nice guys, but a little too laid back.

I once saw a switch that some smart CWO had mounted a push button switch on the S-14 plastic case, after he had super glued it back together. Good field fix!
 

DieselAddict

Well-known member
Steel Soldiers Supporter
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Efland, NC
Diesel fuel
I would recommend taking the top off the engine compartment and cleaning everything well with some degreaser. Once everything is clean and dry start up the fuel pump and let it run while you look around for leaks. With luck it will show itself pretty quickly.
 

Triple Jim

Well-known member
1,375
286
83
Location
North Carolina
I would recommend taking the top off the engine compartment and cleaning everything well with some degreaser. Once everything is clean and dry start up the fuel pump and let it run while you look around for leaks. With luck it will show itself pretty quickly.
Once it's clean, it can also help to put a thin layer of talcum powder around the area to make the leak show up better.
 
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