MEP 802 Shunt wires cut

[PoP PoP]

Special note (I think I figured it out but could I get verification Third post down) I have tried to help myself by reading and computer searching. I need some more help. Why would someone cut 10 inches of wire from the M4 shunt. They cut them off real close at the shunt and then back to where they bundle up in the harness. Thoughts? The answer I have not been able to find is .. three wires connect to one side and three wires connect to the other side. Which three connect to the side next to the wall. Right side facing the panel. See the picture. I obviously found the other ends just have not found a resource that would tell me which side they go to wire numbers are 159A, 112B, 112A, 158A, 109J, and 109K I can tell that 112B goes on the left, yellow connector 12 Gauge. I do see where they go on the schematic but not actually to the shunt, to be honest I do not really know what a shunt is. I read and understand it is a low resistance conductor so that the ammeter will measure at the correct ratio of voltage drop. Post too long which wires hook on the right side? Thank!

​ :edited here: Yes but I do not see the info that tells me what I need to know It shows them connecting to terminal block type representation. I think I figured it out by deductive thinking and your Question. left side 12 gauge wire 112b also 112A then on the small screw to the side connect 159A The right side would then have to be 109 J 109K and the side screw 158A. Your question made me look again. Now all I think I need is verification.

 

[Farmitall]

Is there a schematic plate riveted inside the door of the 802a like there is in the 803a sets?

 

[PoP PoP]

Yes but I do not see the info that tells me what I need to know It shows them connecting to terminal block type representation. I think I figured it out by deductive thinking and your Question. left side 12 gauge wire 112b also 112A then on the small screw to the side connect 159A The right side would then have to be 109 J 109K and the side screw 158A. Your question made me look again. Now all I think I need is verification.

 

[kloppk]

I think you have a typo. Should be ...
Left side 112B, 112A on large terminal 159A on small screw
Right side 109J, 109K on large terminal 158A on small screw

The shunt is just a very low resistance high current resistor.
Current passes thru it when the battery is either charging or discharging.
The current flow causes a slight voltage drop across the shunt. Positive when the battery is charging and negative when its discharging.
The panel meter reads the voltage drop across the shunt to display what the charge/discharge current to/from the battery is.
The panel meter is connected to the two small screws.

 

[Guyfang]

Are the wires long enough to simply put terminals on the and hook them back up on the MT4? Or do you need to "extend" them.

 

[PoP PoP]

I think I can butt connect and then new terminals. Not sure yet. Did you have some advice or trying to figure out why military personnel would cut it like this?

 

[PoP PoP]

I think you have a typo. Should be ...
Left side 112B, 112A on large terminal 159A on small screw
Right side 109J, 109K on large terminal 158A on small screw

I think I have it corrected now I keep wanting to put 159B

 

[kloppk]

... Why would someone cut 10 inches of wire from the M4 shunt. They cut them off real close at the shunt and then back to where they bundle up in the harness. Thoughts?

I suspect the set was giving them trouble and they chopped that section of wire harness out to make the set completely inoperable and not easily repaired. Probably then got a replacement genset.

 

[Guyfang]

I think I can butt connect and then new terminals. Not sure yet. Did you have some advice or trying to figure out why military personnel would cut it like this?

First, I have some suggestions. Then I would ask you why do you think the military did It? Assuming will always get you in trouble.

There are three ways to fix this. Shade tree. Good to go. Or fix it right. All three work.

1. Shade tree. Slap some butt connectors on it the wire ends a extend the wires. Put terminals on the ends, and hook up the wires. Maybe even use heat shrink.

2. Good to go. Get some bulk wire, and rewire it. Four of the six wires go to something in the control panel anyway, so this would not be a big deal. Get the right pins for J6. Push out the old pins, solder or crimp the new wire into the pins, and stick them in. Cut wire to length and put new terminals on them. Hook em up. Mark the wires with wire number correctly.
3. Fix it right. Find someone who had a part gen set. And do not limit yourself to just the MEP-802A or MEP-803A, or even the A model. If someone had a MEP-813A or a MEP-812A, (400 hertz model) it would be even better. Why? The wire numbers are the same, between all the four different models! Iyou can get your hands on a control panel wire harnes, all you need to do is pull out the wires you want to replace, and when you get done, no one would ever know the difference.

The only way I would do shade tree is if I need power NOW. I hate butt connectors. And I know we can get into a long discussion about pros and cons. I have professional crimping tools, and do it when I must, or the customer wants it. But I would never stake my life on it.

For me the fix it right is the standard. I might do the good to go method, in the meantime so I had an operational gen set, but would fix it right at some point later. Some of the guys in the forum are gen set dealers. I think you might find someone to come up with a wire harnes.

Tip. If you are going to open up the wire harnes, take a crap tree full of wire ties, and lace them very loosely around the harnes, about where the old ones are located. THEN, cut the old one out. That way, when you are done, you simply pull the new ones tight, and it's looks clean.

Tip. If you are going to replace wires, with new wires, try this. Tape the new wire to the old wire, and pull it through the wire bundle. Of course you have to loosen up the bundle first. It looks much cleaner then simply taking a few wire ties and attaching the new wire to the outside of the bundle.

Tip. If you pull the wires through the bundles, it easyer to pull the wire through first, then hook the terminals up. Everything slips through much easyer. If the wire is hard to pull through, find out wher it is binding. Nothing will wear a hole through wire insulation faster then another wire.

Tip. If you are going to simply use bulk wire, don't cheat on the gage, and if you can get aircraft grade wire, do so. It's much better wire.

 

[PoP PoP]

Errrr hope not

I suspect the set was giving them trouble and they chopped that section of wire harness out to make the set completely inoperable and not easily repaired. Probably then got a replacement genset.

 

[PoP PoP]

Not intended to be a Slur to military personnel. But point noted. Thank you for your opinions and tips, they are helpful. I will Shade tree until I make power and then probably good to go it then. Yes I want it clean which ever way I go. Your input respected and appreciated.

First, I have some suggestions. Then I would ask you why do you think the military did It? Assuming will always get you in trouble.

There are three ways to fix this. Shade tree. Good to go. Or fix it right. All three work.

1. Shade tree. Slap some butt connectors on it the wire ends a extend the wires. Put terminals on the ends, and hook up the wires. Maybe even use heat shrink.

2. Good to go. Get some bulk wire, and rewire it. Four of the six wires go to something in the control panel anyway, so this would not be a big deal. Get the right pins for J6. Push out the old pins, solder or crimp the new wire into the pins, and stick them in. Cut wire to length and put new terminals on them. Hook em up. Mark the wires with wire number correctly.
3. Fix it right. Find someone who had a part gen set. And do not limit yourself to just the MEP-802A or MEP-803A, or even the A model. If someone had a MEP-813A or a MEP-812A, (400 hertz model) it would be even better. Why? The wire numbers are the same, between all the four different models! Iyou can get your hands on a control panel wire harnes, all you need to do is pull out the wires you want to replace, and when you get done, no one would ever know the difference.

The only way I would do shade tree is if I need power NOW. I hate butt connectors. And I know we can get into a long discussion about pros and cons. I have professional crimping tools, and do it when I must, or the customer wants it. But I would never stake my life on it.

For me the fix it right is the standard. I might do the good to go method, in the meantime so I had an operational gen set, but would fix it right at some point later. Some of the guys in the forum are gen set dealers. I think you might find someone to come up with a wire harnes.

Tip. If you are going to open up the wire harnes, take a crap tree full of wire ties, and lace them very loosely around the harnes, about where the old ones are located. THEN, cut the old one out. That way, when you are done, you simply pull the new ones tight, and it's looks clean.

Tip. If you are going to replace wires, with new wires, try this. Tape the new wire to the old wire, and pull it through the wire bundle. Of course you have to loosen up the bundle first. It looks much cleaner then simply taking a few wire ties and attaching the new wire to the outside of the bundle.

Tip. If you pull the wires through the bundles, it easyer to pull the wire through first, then hook the terminals up. Everything slips through much easyer. If the wire is hard to pull through, find out wher it is binding. Nothing will wear a hole through wire insulation faster then another wire.

Tip. If you are going to simply use bulk wire, don't cheat on the gage, and if you can get aircraft grade wire, do so. It's much better wire.

 

[Bmxenbrett]

I wouldnt bother trying to figure out why there are wires cut. You may never know why.

It also dosnt matter what side of the shunt the wires goes to as long as all the correct wires are connected on the same stud. Aka it dosnt matter if wire 1 and wire 2 are on the right or left side...as long as wire 1 and 3 arnt on the same stud.

The diagram dosnt show what wires are connected to the shunt?