D-180 Electrical System

[JamesBe1 84]

A couple of months ago, A nut came off the linkage on the control plate, and when I stepped on the brake, a couple of the metal rods and linkages moved way too far and shorted out some wires down by the solenoid. Lots of nice sparks and stuff. I quickly shut it off and put everything back the way it should have been. There didn't appear to be any damage to the electrical system. After I got everything back together, it started and ran just fine.

Fast foward to last week. My tractor had been sitting for about a week and a half without running, and I went to move it out of the shed to remove one of my other tractors. The battery was dead. I put it on the charger for a while, but it didn't seem to take any charge. I used jumper cables to connect it to another tractor, and it started fine. I didn't run it for long, I just wanted to verify that the battery was bad.

So, I got around to installing a new battery a couple of days ago, and it started and ran. I got halfway across the yard, and I smelled something electrical burning. Before I could shut it off, I noticed the smoke coming from the right side. I shut if off, and found the wire from the battery to the switch had melted. Really melted, with charred insulation and exposed copper. It was pretty bad.

Dunno what caused it, but I replaced the wire, and I wasn't sure what gage to use, but I think the one I installed was a slightly heavier gage.

I then turned the key to the run position, and a couple of seconds later, I noticed smoke coming from the engine area. I shut it down, and after pondering it for a short while, replaced the coil and condensor with one from my parts tractor. While I was doing the swap, I took the opportunity to ohm both of the coils out. The old one was 6.2 ohms, and the new (used) one was 5.9 ohms. The old one probably wasn't bad, but I continued with the swap anyhow.

Got it back together, and turned the key. Smoke again from the engine area. I pulled the points cover, and they look a bit worn, but not at all burnt. They didn't feel even slightly warm.

I turned the key again, and noticed the smoke coming from the engine shroud area. I killed the key, and felt the wires from the engine to the rectifier (stator wires?). They were very hot, and were the source of the smoke.

I figured the rectifier was bad, so I got the one off of my parts tractor and made the swap. I checked the old rectifier, and one of the AC connectors was shorted to the B+ connector, and the other AC connector was open. I checked the resistance in both directions.

I turned the key to the run position, and felt the stator wires, and they were very hot again. Too bad I didn't check the replacement rectifier before I installed it If it wasn't bad before I installed it, it most likely is now.

I have a new rectifier on order, I certainly don't want to burn it up right after installing it. Anyone got any ideas of what else to check and how to check it?

That was yesterday. This evening when I got home, I set about removing the FEL. Not easy when the tractor doesn't run, but I finally got it off. One last thing I checked, I pulled the plug off of the rectifier and checked the resistance from the wires to ground (tractor frame). 0 Ohms. Correct me if I am wrong, but it seems my stator is shorted. Anyone else see it that way?

A couple of points to consider about the electrical system:

1) I added an electric fuel pump, and am taking power off of the ignition wire on the back of the key switch.

2) I changed the ammeter to a voltmeter and wired it to the battery wire on the back of the key switch.

[1maidenfan 202]

Looking at the wiring diagram in my manual , I would lean more to it being a short in the ignition switch. R connector on back of switch (orange wire) goes to the rectifier.

The stator is under the flywheel and is not the same as the rectifier.

Dont ya just love electrical.

Keep us posted.

[Trouty56 567]

Start it and run it off the battery....bypass everything....then start adding things....like said above it is most likely a shorted switch or the like. When you are running it off the battery then check the stator wires....should be ac current like 28 volts between the two or something.

[tommyg 154]

Yikes! I think I'll take my hydro motor rebuild over your electrical problem any day! Ditto 1maidenfan. Keep us posted!

[JamesBe1 84]

Great ideas guys.

I think I'll use jumper cables to hook the battery to the other tractor and try to run it.

I can't hook the stator wires to the rectifier without it smoking the wires, but once I get it running, I can check the output at the end of the wires.

I kinda get the idea that the battery is draining through the switch, then through the rectifier, then through the stator to the frame.

Also, the wires on the back of my switch are a bit messy. I have a couple of double wires hooked to one connector. It would be an odd coincidence if the switch were bad. The switch on my C-120 just died last week and I had to replace it with my spare (new) one. Stranger things have happened.

I would post pics, but there isn't much to look at.

Can anyone tell me if I should get 0 ohms between the two stator leads? I get that in addition to 0 ohm from either lead to the frame.

[JamesBe1 84]

Hmmmm. The plot thickens!

I got my new rectifier today, and this evening I checked it against the original one from the tractor (not the one off of the parts tractor that is on there now). They ohm out almost exactly the same. So I guess I now have a spare rectifier.

I dug out my spare stator (from my parts tractor), and ohmed it out. It was a short between the two leads (which I expected), and it was open between the leads and the metal ring (not sure what to call it, it's the metal part that the individual coils are secured to that bolts onto the engine).

I rechecked the stator that is on the tractor, and it is a short between the leads and the frame. I guess one of these things is not like the other!

I spent the rest of the evening until dark towing it and ratcheting it (with a come-along) up the hill to my shed. I guess tomorrow I'll start to removing stuff so I can get to the flywheel to remove it.

It should be interesting!

At least I can also take this opportunity to tighten up the stack muffler pipes that are loose and add 1" nuts to them to help keep them from loosening.

[1maidenfan 202]

Glad to hear you have found your electrical problem. To bad it wasnt the ignition switch as its a lot easier to change.

Go luck and have fun.

[Save Old Iron 1,571]

I checked the old rectifier, and one of the AC connectors was shorted to the B+ connector, and the other AC connector was open. I checked the resistance in both directions.

James,

the RR unit is hardwired from the B+ terminal to one of the AC terminals, If you pick away at the sealant on the RR unit, you can see they are staked and soldered together on the pc board.

As far as using the multimeter for a resistance forward / reverse diode type check, forget that, There is more to the RR pc board than just diodes.

Good troubleshooting on the stator. I'm not sure about the 30 amp stator RR combo, but the 20 amp stator should not show any resistance from the windings to the stator core.

Most likely you will find the windings discolored with burned insulation.

If you want an alternate test to confirm the stator is defective prior to removing the flywheel, try to measure at least 30+ VAC across the stator leads at full throttle.

[JamesBe1 84]

Thanx for the excellent info Save Old Iron. It is a great help. Are those your shots of the rectifier? If so, did you use anything to soften the epoxy? What did you use to chip it off?

Thanx,

j

[Save Old Iron 1,571]

Thanx for the excellent info Save Old Iron. It is a great help. Are those your shots of the rectifier? If so, did you use anything to soften the epoxy? What did you use to chip it off?

Thanx,

j

James.

that info was from an "autopsy" post I made a few years back on the old red square site. Those pics are from a non-functional RR unit I took apart solely as a learning experience about RR units. The RR terminals are supported by some sort of resin impregnated cardboard. The cavity of the heatsink assy and pc board was (mostly) encapsulated by what appeared to be a very durable expandable foam.

The visible surface of the pc board was coated in a silicone like conformal coating. All material had to be removed by mechanical means - scraping and tearing away.

[JamesBe1 84]

Got my engine off this morning, and removed the tin and flywheel. I think I found the problem.

I used a puller to removed the flywheel. Interesting to note that the flywheel nut was loose, and I neglected to bend the tabs of the locknut. This might have lead to it's ultimate demise, dunno.

Here are the autopsy photos:

Broken Flywheel:

Damaged stator:

Now I am in the market for a new flywheel and stator :(

[Save Old Iron 1,571]

James,

most unfortunate. The condition of the stator does explain why you have continuity of the stator leads to ground. Hope replacement parts come your way very quickly.

Thanks for the quick update to the post. I have seen loose magnets destroy stators. I have not seen a flywheel let loose like that. I'll make a note to check that on my D200.

[JamesBe1 84]

James,

most unfortunate. The condition of the stator does explain why you have continuity of the stator leads to ground. Hope replacement parts come your way very quickly.

Thanks for the quick update to the post. I have seen loose magnets destroy stators. I have not seen a flywheel let loose like that. I'll make a note to check that on my D200.

Thanx my friend. Upon closer inspection, I found that the crankshaft is broken also. Not my lucky day.

The silver lining is that this is motivating me to finish the rebuild of the spare K482 that I had. Maybe in a week or two I'll be ready to fire it up.

[JFleetwood1977 0]

So here is my question... What does the B+ terminal go to and does the ac terminals go to? If the ac terminals connect to the stator does it matter which terminal goes to which wire?

[Trouty56 567]

The wires from the stator carry ac current and it doesn't matter which terminal on the rectifier they connect to other than the B+ terminal. The B+ terminal on the rectifier connects to the R terminal on the ignition switch.

[JamesBe1 84]

The wires from the stator carry ac current and it doesn't matter which terminal on the rectifier they connect to other than the B+ terminal. The B+ terminal on the rectifier connects to the R terminal on the ignition switch.

Perfect. I couldn't have said it better.