John Deere 730 24 volt electric start switch backside

[andy r]

Attached is a photo of the backside of the light switch for a John Deere 730 diesel 24 volt electric start. I can see the two coil resistors which must dim the head lights. One resister for each side. But what is the metallic disk shaped thing the needle nose pliers are pointing to? It is riveted to the copper strap underneath. The electrical connector says GEN. The electrical connector and little washer are riveted to the top of this metallic disk. The reason I tore it apart was there initially was no continuity from the copper strip on bottom side to the electrical connector on the top side through this metallic disk. Thanks for the help.

 

[andy r]

Picture of switch backside

 

[wore out]

As I have posted before it is a resistor to allow the use of a standard 12 volt lamp as a generator charging indicator on a 24 Volt circuit.

It has a value of around 50 Ohms.

I even posted a scan from a DEERE service manual showing it in the circuit.

Are my posts not visible to you or don't you believe what I am telling you?

<img src = "https://i.imgur.com/NOruS8Y.jpg">

<img src = "https://i.imgur.com/tGe8PAp.jpg">

From Page 40, Service Bulletin 268, 24-Volt Electrical System.
Previous

 

[James Howell]

"[b:654c4848f0][i:654c4848f0]what is the metallic disk shaped thing the needle nose pliers are pointing to?[/i:654c4848f0][/b:654c4848f0]"

That is the GEN terminal.

Take a look at the photo below.

Take a look at the [b:654c4848f0]GENERATOR, IGNITION, AND WIRING[/b:654c4848f0] diagram below.

Note the [b:654c4848f0]BLACK[/b:654c4848f0] wire from the GEN terminal on the switch to the Generator Light Indicator.

Also note the [b:654c4848f0]BLACK[/b:654c4848f0] wire from the Generator Light Indicator to the [b:654c4848f0]FLD[/b:654c4848f0] post on the Generator.

Hope this helps.

 

[Mike M]

Don't see a photo ?
The little copper rivets IIRC that are for dog tags work good to make replacement contacts for those switches. I think that is what the ones I used were.

 

[NoDakInMN]

(quoted from post at 23:19:30 05/16/20) As I have posted before it is a resistor to allow the use of a standard 12 volt lamp as a generator charging indicator on a 24 Volt circuit.

It has a value of around 50 Ohms.

I even posted a scan from a DEERE service manual showing it in the circuit.

Are my posts not visible to you or don't you believe what I am telling you?

&lt;img src = "https://i.imgur.com/NOruS8Y.jpg"&gt;

&lt;img src = "https://i.imgur.com/tGe8PAp.jpg"&gt;

From Page 40, Service Bulletin 268, 24-Volt Electrical System.
Previous

Lighten up Francis. They guy is trying to figure out a problem, not taking time out of his day to insult you.

 

[55 50 Ron]

James,

I'm curious as to where you found the nice picture of the rear of this switch. Maybe you have a 24 volt system in one of your tractors?

 

[andy r]

Thank you, thank you very much. I was trying to talk myself out of the fact that a chunk of metal could be a resistor. I am sorry you had to take me through this a couple times. Thanks again.

 

[wore out]

(quoted from post at 16:32:09 05/17/20) Thank you, thank you very much. I was trying to talk myself out of the fact that a chunk of metal could be a resistor. I am sorry you had to take me through this a couple times. Thanks again.

HEY! Glad you are getting this figured out!

I would GUESS the "disc" is actually some sort of carbon or graphite.

At some point in the 24 Volt era they eliminated the resistor for the indicator light on the switch and used a resistor (R39550) that plugged into a wiring lead from the indicator light in the instrument panel.

Any more issues getting this working, post back, I will do my best to help you with this "odd" (to many guys) electrical system.

 

[James Howell]

"[b:654c4848f0][i:654c4848f0]where you found the nice picture of the rear of this switch[/i:654c4848f0][/b:654c4848f0]"

That picture is courtesy of [b:654c4848f0]S T I E N E R[/b:654c4848f0] Tractor.

They include a very good instruction sheet with their combination switches.

The photo below shows the switch installed in a couple of our Model 70s.

 

[James Howell]

Sorry about that - forgot to upload the picture.