Model 12046 1950 MC- Question about Electrical System

[RHT]

I bought a 1950 MC last year and am confused about my electrical system. I just replaced the alternator belt and was told by a mechanic that I had a 12 volt alternator. My electrical system was originally designed for 6 volt but I have a 12 volt battery. Near the coil is some kind of ceramic block and I'm not sure what its function is . All I know is that after replacing the fan belt, I started the crawler and immediately some wires running to the alternator plus burst into flames. I was able to get the fire out and suspect that I may have some issue with my charging system . I need to know if I should revert back to a 6 volt system or how I could remedy my electrical system so that I can safely run my crawler with 12 volts .

[Lavoy]

The little white block is a ballast resistor to drop the voltage down going to the coil to prevent burning the points. Your crawler would have had a generator, not an alternator.
What to do is personal preference I guess, but as a general rule, I like to go back to what the machine was built with.
Lavoy

[RHT]

Actually if this 1950 MC was originally designed for 6 volts then I would prefer to revert back to a 6 volt system. If I get a 6 volt battery and replace the sections of wire that caught fire, then I could proceed without any other modifications ? I don't really have access to anyone nearby to consult and the work that I had done for my bull gear/ shims and bushings, I had a business named Niche out of Hornell, NY contact the administrator of this forum for the parts he installed.
Thanks,
RHT

[Stan Disbrow]

Hi,

Model 12046? Is that your serial number?

The M series was 6 volt, positive ground using a 3-Brush generator and a single relay for cut-out.

The later series (40 and up) used the same 6 volt positive ground, but with the more common 2-Brush generator and 2 relays. One for cut-out and one for voltage regulation (both inside the same voltage regulator housing.

So many machines were converted, usually badly, to 12 volt negative ground. Not just crawlers, and not just Deeres, but everything. So, the 6v parts are going to cost dearly (should that be Deere-ly?) compared to the nowadays-ubiquitous 12 volt negative ground one-wire alternators....

Oh, and one of the badly done things during 6v-to-12v conversions is no one seemingly changes the poor starters. 12v is hard on starters, and harder on the ring and pinion gears....

Your wiring must be shot, too, since something went short-o-matic to flame out like that. Unless...someone put the 12v battery in positive ground like the original 6v was. That makes smoke and flame once the machine is started and the alternator tries to be a battery discharger.....

Anyway, the 12v fix is go to a one-wire alternator. Run a new wire to the pos battery terminal. Run another new wire from the pos battery terminal and to a new toggle switch, then from the switch to one end of that resistor. Then from the resistor to the distributor. I would use new wire for that as well.

Disconnect all other wires from the battery. Done. If you have lights, use new wires and a new switch there, too.

Doesn't help the poor starter, though. Which, is probably half cooked anyway, and so would no longer work too well on 6v....

Stan

[RHT]

I believe that my battery must be grounded wrong as my wires caught fire as soon as I started the engine. A section of wire burnt before I caught it and now that I have this issue with grounding what must I do to remedy this. Do I reverse the wires on the battery or do something else entirely ?

[Lavoy]

I would probably put a new wiring harness on the crawler, rebuild a correct generator, new battery and cables, and new cutout, then you know it is done right.
Lavoy

[RHT]

I did find out that my 1950 MC had been converted to a 12 volt system which included a Delco Remy Alternator. I loosened the belt so it had 1/2 " slack in the middle of the belt. I also found an ignition wire that was bare in one spot and had shorted out to ground. I replaced the alternator plug and put in an in line fuse. I also tightened all the connectors and replaced some taped wires that were twisted together with butt connectors. After I was done, I started crawler and it ran fine with no electrical hot-spots. I appreciate all the comments and feedback that helped me work my way through this problem.

RHT

[Stan Disbrow]

Hi,

Ign wire shorted to gnd would explain a lot. Sounds better now.

No, don't change the battery polarity as that will not make the alternator happy and you will be back to letting smoke out.

Stan