MEP802A Burnt Wires

Hey all,

Well.. I officially feel like the annoying new guy to the group, but I appreciate the help-- THANK YOU!

Opened up some covers on my 802a and was looking things over, and I noticed some wires that have gotten pretty crispy. It looks like they've been this way a while, doubt it's happened in the 2 hours I've run the unit. 230 hours on meter. Running pretty well and generating power, easily maintaining a 40% load.

Crispy (melted/bare) wires are all related to S5 (AC Circuit Interruptor Switch) and K1, main AC relay. Wire 100A from the switch to terminal 7 on the 24-terminal bus bar is fried. Not sure where the other wires from Terminal 7 go right now. Wires 152B, 152C, and 152D going from S5 to bus bar terminal 16, then through the frame, then to K1, are all gone. 152D is what attaches to terminal "Y" on K1 (relay).

Is this any sort of common/known problem? I'm assuming, to some extent, these are signal wires for the relay, and shouldn't carry much current, but something must be shorting or drawing current.. duh.

Thanks in advance!

I'll add, the two wires burnt up connect to the S5 switch at terminals 5 and 6, which close when the switch is lifted up, thus closing the K1 relay and allowing power output. As mentioned above, one of them (I forget if its 5 or 6) ends up at the "y" terminal on K1, and the other, seems to go a handful of places (terminal 7 on the 24-terminal bus bar, to start)

I would predict that at one point you had a defective S5 switch and it shorted directly to ground but it has since been replaced. Terminal 6 goes to TB5-7 which is ground. Terminal 5 goes to K1-Y which closes K1 contactor and terminal 3 goes to K8-7 overload/ short circuit relay. When K8 trips due to an overload or short circuit it disconnects power to K1 through S5.

Later today I will post something to help.

Thank you. Kinda what I was leaning towards, something shorted to ground. I'm not super savvy with electronics and a bit of a slow learner... I'm sure a lot of this is "in the manuals" but I struggle with that.

Can I get a little schooling on how this system works. When lifted up, S5 sends a signal to K1 to close, but it's just a momentary signal, right? The Switch returns to it's middle position, contacts open, but K1 stays closed. Is K1 latched closed until told to open, or is it getting signal from somewhere else after S5 is released? When S5 is pushed down to turn power off, K1 opens. Again, does it send another signal to Un-latch it, or does it just break the signal? What is K1-X fed from?

You guys are awesome, thank you!

Yes, momentary signal. The S5 tells the K1 to close. Then the S5 springs back to the middle position. The K1 stays closed until the S5 is pushed down, telling K1 to open, OR a saftey relay, tells the K1 to open.


This any help?

Thank you Guyfang, I appreciate the chart. Can I ask where that's from, so I can perhaps save asking in the future? Or, did you make it yourself?

What wire/terminal on K1 tells it to open? (Since the S5 signal is momentary and not holding the contacts together via energized coil)?

Also, trying to wrap my head around the "terminology" and nomenclature of these. For example, in the bottom of the K1 chart, Wire 152D goes from P6-35 to Y. What is P6-35, and again, where is this info coming from? I feel I'm on the verge of this all clicking and making sense, but not just yet. Thanks again.

I made this list myself. I have gone back to working on it and triple checking that I have it all and its right. Sooner or later I will get it done and put it in the Forum.

P6-35 means P6 plug. 30 is the pin number in the plug. P6 has a mate, the other side of the connection. Its J6. P for plug, J for Jack. Easy

X & Y are what tell the K1 to open and close. They are the K1 coil wires.

If you look at K1, MAYBE the wire positions will still be numbered. The decals tend to fall off.

K1 11 &12 are to turn on the light next to S5.

Thanks for the J6/P6 explanation. Like you said, easy... now that I know. Nice charts as well, would love to see them all published some day!

What I'm still lost on is this: When K1 is closed, do wires 152B, 152C, and 152D (from S5-5) have current flowing through them.. causing my short/melted wire? I assume they'd need current to energize the coil, unless it latches, and X releases it.

Where can I find a list of all the connections, plugs, pins, etc, or does it not exist? For example, I would like to to backwards from K1-x. your chart tells me 150B goes to P6-29, which would presumably go to J6-29, but then where?

Feeling a little better about all this. I was tempted to ebay the darn thing yesterday because I felt pretty overwhelmed, but I think I can do this!

Guyfang said:

I made this list myself. I have gone back to working on it and triple checking that I have it all and its right. Sooner or later I will get it done and put it in the Forum.

P6-35 means P6 plug. 30 is the pin number in the plug. P6 has a mate, the other side of the connection. Its J6. P for plug, J for Jack. Easy

X & Y are what tell the K1 to open and close. They are the K1 coil wires.

If you look at K1, MAYBE the wire positions will still be numbered. The decals tend to fall off.

K1 11 &12 are to turn on the light next to S5.

Click to expand...

Maybe I just answered my own question about most the wires, the wiring diagrams inside the doors, duh. I now nee that There are j's and p's grouped together. It's making sense... I'm a slow learner. Still wondering about current flowing through the wires from S5 to K1.

Have you downloaded the TM from the Forum here? All the TM's are there, and the re is a package of schematics in it extra. They are "better" then most of the normal ones in the TM, but only maybe.

If I can do this, you can do this!!!!!!!!!!!!!!!!

I would write more, but got to take my grandson home.

Later,

guy

I seem to have downloaded a mish-mash of manuals and I'm not sure I have the right ones/bet ones. I see -24 mentioned for TM's... would you be so kind as to provide me with a link to the right/best one? I think I downloaded one that you posted, but I'm not positive.

Thank you very much for the time and help thus far.

Guyfang said:

Have you downloaded the TM from the Forum here? All the TM's are there, and the re is a package of schematics in it extra. They are "better" then most of the normal ones in the TM, but only maybe.

If I can do this, you can do this!!!!!!!!!!!!!!!!

I would write more, but got to take my grandson home.

Later,

guy

Click to expand...

www.steelsoldiers.com/showthread.php?175591-MEP-803A-All-the-TM-s-you-need

Its in the TM forum, Generator section, top of the page, page #3

Download it all. The long black box has a total of 4 TM's in it. You just cant see them. hold your pointer over the black places, and the title will come up.

Thank you, didn't realize they were separate documents. Got them all downloaded and will begin reading.

I just noticed that K8-7 and K8-8 have an ugly jumper between them, which is starting to make more sense as to why I have some melted wires to do with K8, S5, and K1. So, K8 Current Overload is "permanently battle-shorted" (K8-7/8 get closed by battle short switch)

Wonder if K8 relay is bad, or if the jumper was a fix for some other problems. I'll keep digging.

Guyfang said:

www.steelsoldiers.com/showthread.php?175591-MEP-803A-All-the-TM-s-you-need

Its in the TM forum, Generator section, top of the page, page #3

Download it all. The long black box has a total of 4 TM's in it. You just cant see them. hold your pointer over the black places, and the title will come up.

Click to expand...

Small update, K1 wont stay closed without K8-7 and K8-8 connected together. I'll read up on testing K8 to see if it's getting a bad input and doing its job, or if it's burnt up and wont keep those terminals closed under normal conditions.

Hook up the wires right on the relays. Start the set. Flip up S7. Try and turn on S5. Will it close K1? If K1 closes, what idiot light comes on?

Replaced all the burnt wires. Added the 3A fuse on A1-8. Removed jumper on K8, started set. With Battle Short closed, S5 closes K1 and I get power. With Battle Short open, S5 only closes K1 while the switch is held up. No fault lights illuminate at any time, except when tested, they all work.


https://www.youtube.com/watch?v=xNX4uDRCS6M

fastbrass said:

Replaced all the burnt wires. Added the 3A fuse on A1-8. Removed jumper on K8, started set. With Battle Short closed, S5 closes K1 and I get power. With Battle Short open, S5 only closes K1 while the switch is held up. No fault lights illuminate at any time, except when tested, they all work.


https://www.youtube.com/watch?v=xNX4uDRCS6M

Click to expand...

You need a K8.

I’m glad you said that, because I ordered one on fleabay last night. I didn’t even bother testing K8... because it seemed pretty broken.. lol. Thanks for the help Guyfang!