Hot Wire!

[beguz]

Installed a new 6V battery yesterday and immediately saw a lot of smoke coming from under the engine cover. Quickly disconnected the battery. Wiring very hot to touch. Did a couple tests (quick reconnect / disconnect of the battery and watched for source of smoke), pinpointed the wire from the ammeter to the starter as the source. The connection at the ammeter glows brightly (Ok, it's almost on fire) as soon as the battery is connected. The wire is now pretty much shot ... insulation melted in a number of places. I haven't replaced the wire yet, but suspect there's more going on than just the bare insulation. I pulled the wire aware from the engine block and everything else so it's not touching anything, but made no difference.

Any suggestions? Is the ammeter the problem?

Tractor was fine last time I used it ... about a month ago. Old battery gives same bad result as new one.

[Cub-Bud]

Sounds like a short in the ammeter I would replace the ammeter and the wire.

[Bigdog]

The glowing and smoking at the ammeter is indicative of a loose or corroded connection which will generate heat under high current situations. No doubt there is damage to the wire and likely the ammeter. However, this may be only part of the problem. You need to find out why there is such a high current flow. There must be a complete path for current flow so you need to find the path. Start by removing the connections to the opposite terminal of the ammeter and then re-connect the battery to see if there is still a drain. If so, then the short to ground is indeed in the ammeter. If not, there is another short somewhere. The most likely path is through the voltage regulator or cut-out to the generator. This would only happen if the contacts on the regulator or cut-out were burnt and stuck together so that is another place to look.

[beguz]

Big Dog, I removed the 2 wires from the opposite terminal and re-connected the battery. No drain (or smoke or light). Absolutely nothing. Suspicious, I reconnected the wires and tried again, and again absoluting nothing. So, unlike yesterday, it's like there's no current at all. Checked the battery, it's still reading 6V. So something else went bad?

Also, I couldn't locate the regulator. From parts diagram, it looks like it's between the magneto and generator, but I don't see it there.

Appreciate any and all advice!

[Bigdog]

Look on top of the generator. What year cub are we dealing with? And do you know if it is a cut-out or regulator? You mentioned a magneto so I'm guessing it's an early cub.

[beguz]

1948, serial # 55479. Oh, top of generator? Can't see what's up there. No, don't know what you mean by a cut-out.

[Bigdog]

early cubs used a 4 position light switch and a cut-out relay to control the charge rate. The light switch was marked L H D B indicating Low charge, High charge, Dim and Bright. The generator field winding was grounded through the light switch either directly to ground (High charge) or through a resistor to ground (Low charge) to control the charge rate. The cut-out relay opens the charge circuit when generator output is lower than battery voltage. This prevents the battery from being drained back through the generator windings.
My suspicion is that you have or had a stuck cut-out relay and the drain was through the generator windings. In either case, I'd remove the hood and open the cut-out to check the contacts.
You will, of course still need to replace the wire to the ammeter and check the ammeter itself to assure it has not been damaged.

[beguz]

My cubbie's light switch is 3 positon marked O D B. What does the O stand for? Does this change the explanation much? Where exactly is the cut-out relay located?

Thanks for spoon feeding answers to me![/quote]

[Bigdog]

The three position switch is Off Dim Bright. It would also indicate that you have a voltage regulator rather than a cut-out. You might check to insure that the switch truly only has 3 positions. Sometimes the wrong decals get installed.

[beguz]

Good suspicion. It is a 3 position decal on a 4 position switch. The first 2 positions on the left are close to each other, then the next two are spaced out farther to the right. I haven't used the switch for a long time since my lights don't work because the fuse burns out as soon as I put one in. Maybe this is another clue to the root of the problem?

OK, so if I have a cut-out relay, where is it located? And, if I need a new one, suggestions on where to get one?

[Bigdog]

Look on the left side of this page. It shows the cut-out relay mounted on top of the generator.

http://www.cleancomputes.com/Cub/Cub%20 ... 008-02.jpg

[beguz]

OK, thanks Big Dog. I'll check it out asap. Unfortunately for me, my cub is outside under a tarp, so I need to wait for good weekend weather to do much work on it. If I need new parts (relay and/or ammeter), suggestions on where to buy ... just go to a local Case dealer, or internet seller?

[Bigdog]

Local Case dealer or NAPA are likely local sources.

[beguz]

You need to find out why there is such a high current flow. There must be a complete path for current flow so you need to find the path. Start by removing the connections to the opposite terminal of the ammeter and then re-connect the battery to see if there is still a drain. If so, then the short to ground is indeed in the ammeter.

... and, the answer is, the short to ground is indeed in the ammeter. Did just as you suggested, big dog, and based on that bought a new ammeter. My cubbie is purring, maybe even better than ever. So, thanks to you and this great forum, one more old cub lives on! (and now has to go back to work ... we have a field to mow )

[Bigdog]

We aim to please!