Smokin Light Switch

Sun Jul 18, 2004 10:40 am

After rewiring my '48 Cub the light switch smokes at the field resistor.
Have had problems with charging and a possible battery drain.
I cleaned all connections, polarized generator, have new battery, inspected generator and starter brushes...checked cut-out...contacts were open.
The switch is a 3 position (see below), I used a H/M wiring schematic, I've a cut-out relay.
Also, have push/pull kill switch, and push to start button (not lever).

Originally, the F generator post had a short wire going to the F on the cut-out....I removed that and ran the original wire from field resistor (wasn't being used) to the F post on generator. All the lights were wired to the #2 post on light switch ...the #3 wasn't used. Lights are disconnected at this time.
Its charging at 10-12 amps.

Also, the starter drags....after shutting everything down....it will hardly turn over and there's gas coming from the bottom of the carb.

3 position switch?...I've 0, 1, 2 3 clicks/positions, back of it looks like the H/M schematic (4 position), have after market stickers saying O,D, B....switch positions aren't strong...feels like its wore out...easy to miss the 1 position with out babying the knob.
Whew!
thanks

Sun Jul 18, 2004 12:10 pm

You're describing a 4 position switch. (off is a position too)(actually it's low charge position) With the switch detents being barely perceptable, I am guessing that the switch is very worn and the contacts are not making tightly. Loose contacts generate heat and thus, smoke. If you feel comfortable doing so, dis-assemble the switch, clean and tweak the contacts to see if you can make them better. Or, look for a replacement switch. Charging at a rate of 10 to 12 amps all the time is not good. You mentioned a Field terminal on the cut-out - that indicates that it is a regulator, not a cut-out. Check the wiring diagram for a regulator and wire it that way.

switch

Sun Jul 18, 2004 12:30 pm

BigDog,
Cut-outs have 3 connections, 1 of which is the Field...2/Battery...3/Generator..or maybe I'm missing something. I popped the cover and there's only 1 component not 2 like a regulator/cut-out combo.
I'll clean the switch like you suggested.
The field resistor gets hot if I turn the light switch knob to 0.
The dimming resistor wire for headlights gets hot when I connect the front lights and turn switch on.
The rear light is o.k.
Thanks.

Sun Jul 18, 2004 12:32 pm

There is a field terminal on a cut-out. If you have lights (and thus a light switch) it is not used. Without lights, it doesn't need to be used most of the time either.

Sun Jul 18, 2004 1:42 pm

Sorry, I must have my head up my a$$ today. Don't know what I was thinking.

switch

Sun Jul 18, 2004 2:14 pm

No problem Big Dog....p.s. my 2 yr. old likes your dog pic.
I'm going to try this....leave the F terminal at Gen. and light switch field resistor connected and then reconnect the cut-out F terminal back to gen. F terminal?
I'm thinking that if the field resistor gets hot when light switch is at 0 position....low charge....the cut-out isn't doing its job?
Or get rid of the F-Light connection...whats it good for?

On other fronts...I think my starter solenoid is giving me the hard to start probelms? After cooling down...she started up....but once again after killing her....she hardly turned over.

Sun Jul 18, 2004 2:34 pm

BD, I was sure you knew that and were just having what some of us can blame on a senior moment. Maybe you are getting there too!

9mules, if I follow, you are planning to connect the generator F terminal to BOTH the light switch and the cut-out F terminal. If you do that and the resistors are both good and the connections are all good, the low charge rate will be boosted up to somewhere between the normal low charge (1 or 2) and the normal high (10 or 11). The high charge rate will not change. Since the field current will be split between the 2 resistors, the current in each will be reduced.

Another option is to just directly ground the generator F terminal, permanently setting the high charge rate. Unless you use your tractor more heavily than most of us, you never need low charge anyway.

How long has it been since the light switch was used? The smoke may just be crud burning off the resistors. After a while they may quit smoking with no damage.

cooking

Sun Jul 18, 2004 5:26 pm

Jim, the lights worked last week, this week I cleaned all contacts and did the rewiring.
I'm going to remove the new F wire and go back to my orginial set-up.
The biggest problem now is my starter can't turn the engine over....it's been that way since I bought it even with a new battery.
It works fine when unbolted from the tractor, I'll like to change battery cables to a #2 or 1.
Confirm timing/points are correct. Clean/inspect starter the Chauvin way.
Thanks Cubies

Sun Jul 18, 2004 9:15 pm

You may have a starter problem, but it takes a lot more current to crank the engine than to just spin the starter. First place to check is the battery connections, and the ground connection. If you still have the orignal ground set up (ground cable bolted to the battery box) there is a good possibility the battery box is rusty enough that it is not getting a good ground. If you don't have a voltmeter to check voltage at the starter while cranking it, remove both cables from the battery and use a good set of jumper cables to connect from the battery to the starter switch and from the ground post to one of the starter mounting bolts.

starter

Mon Jul 19, 2004 7:37 am

John & Jim,
Thanks for the info.
I bolted my ground cable to a cleaned spot near the pto weeks ago.
I think Jim mentioned in another post about the ohms for battery cables, I think it was 5? It wouldn't hurt to replace them...green corrosion, missing insulation covered with electric tape.
From what I understand these 6 volt batteries like/need heavy cables to carry as much amps out as possible.
John, I'll check the voltage drop etc. Its the amps not the voltage starters need to compensate for the drag induced by the engine.
I believe we're on the right track.

I think the Field Resistor wire is getting hot (it'll burn your finger) because of resistance in the light switch? Due to being old/dirty & if you don't baby the dial in to the other 3 positions you'd think it was a 3 position switch not the 4....thats led to alot of confusion on my part.

I've owned this '48 Cub for 2 months and with all its troubles its still worth it.
I hope to get her ready for the Fall Harvest Days here in the Smokys.
Thanks,
Curtis

Re: starter

Mon Jul 19, 2004 9:08 am

9mules wrote:John & Jim,

John, I'll check the voltage drop etc. Its the amps not the voltage starters need to compensate for the drag induced by the engine.
I believe we're on the right track.

I think the Field Resistor wire is getting hot (it'll burn your finger) because of resistance in the light switch? Due to being old/dirty & if you don't baby the dial in to the other 3 positions you'd think it was a 3 position switch not the 4....thats led to alot of confusion on my part.


Curtis
A bad or corroded connection will cause a voltage drop at that point when a higher current is passed through it. That's the reason I mentioned checking for a voltage drop.

A higher resistanc in the light switch due to a bad connection should not make the resister get hot. It would increase the resistance which would decrease the current flow. The higher the resistance in the field lead, the lower the charge rate. Is your generator charging 10 to 12 amps in both settings? If so there is a wiring problem somewhere or the third brush is adjusted to close to the output brush causing a higher than normal current to flow.